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  Subjects -> ENVIRONMENTAL STUDIES (Total: 760 journals)
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ENVIRONMENTAL STUDIES (687 journals)            First | 1 2 3 4     

Showing 601 - 378 of 378 Journals sorted alphabetically
Russian Journal of Ecology     Hybrid Journal   (Followers: 1)
S.A.P.I.EN.S     Open Access   (Followers: 2)
Safety Science     Hybrid Journal   (Followers: 18)
San Francisco Estuary and Watershed Science     Open Access   (Followers: 1)
SAR and QSAR in Environmental Research     Hybrid Journal  
Scandinavian Journal of Work, Environment & Health     Partially Free   (Followers: 12)
Science of The Total Environment     Hybrid Journal   (Followers: 16)
Sciences Eaux & Territoires : la Revue du Cemagref     Open Access  
Scientific Journal of Environmental Sciences     Open Access   (Followers: 1)
Sepsis     Hybrid Journal  
Smart Grid and Renewable Energy     Open Access   (Followers: 8)
Social and Environmental Accountability Journal     Hybrid Journal   (Followers: 2)
Soil and Sediment Contamination: An International Journal     Hybrid Journal   (Followers: 3)
Soil and Tillage Research     Hybrid Journal   (Followers: 6)
SourceOCDE Environnement et developpement durable     Full-text available via subscription   (Followers: 1)
SourceOECD Environment & Sustainable Development     Full-text available via subscription  
South Pacific Journal of Natural and Applied Sciences     Hybrid Journal  
Southern Forests : a Journal of Forest Science     Hybrid Journal   (Followers: 6)
Stochastic Environmental Research and Risk Assessment     Hybrid Journal   (Followers: 4)
Strategic Behavior and the Environment     Full-text available via subscription  
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Sustainability     Open Access   (Followers: 18)
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Sustentabilidade em Debate     Open Access  
TECHNE - Journal of Technology for Architecture and Environment     Open Access   (Followers: 5)
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Territorio della Ricerca su Insediamenti e Ambiente. Rivista internazionale di cultura urbanistica     Open Access  
The Historic Environment : Policy & Practice     Hybrid Journal   (Followers: 4)
The International Journal on Media Management     Hybrid Journal   (Followers: 4)
Theoretical Ecology     Hybrid Journal   (Followers: 9)
Theoretical Ecology Series     Full-text available via subscription   (Followers: 1)
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Toxicology and Applied Pharmacology     Hybrid Journal   (Followers: 17)
Toxicology and Industrial Health     Hybrid Journal   (Followers: 8)
Toxicology in Vitro     Hybrid Journal   (Followers: 12)
Toxicology Letters     Hybrid Journal   (Followers: 12)
Toxicology Mechanisms and Methods     Hybrid Journal   (Followers: 10)
Toxicon     Hybrid Journal   (Followers: 3)
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Trace Metals and other Contaminants in the Environment     Full-text available via subscription   (Followers: 2)
Trace Metals in the Environment     Full-text available via subscription   (Followers: 2)
Transportation Research Part D: Transport and Environment     Hybrid Journal   (Followers: 27)
Transylvanian Review of Systematical and Ecological Research     Open Access  
Trends in Ecology & Evolution     Full-text available via subscription   (Followers: 164)
Trends in Environmental Analytical Chemistry     Hybrid Journal   (Followers: 2)
Trends in Pharmacological Sciences     Full-text available via subscription   (Followers: 26)
Turkish Journal of Engineering and Environmental Sciences     Open Access   (Followers: 1)
UCLA Journal of Environmental Law and Policy     Open Access   (Followers: 5)
UD y la Geomática     Open Access  
Universidad y Ciencia     Open Access   (Followers: 1)
Urban Studies     Hybrid Journal   (Followers: 48)
Veredas do Direito : Direito Ambiental e Desenvolvimento Sustentável     Open Access  
VertigO - la revue électronique en sciences de l’environnement     Open Access   (Followers: 3)
Villanova Environmental Law Journal     Open Access  
Waste Management & Research     Hybrid Journal   (Followers: 10)
Water Environment Research     Full-text available via subscription   (Followers: 36)
Water International     Hybrid Journal   (Followers: 10)
Water, Air, & Soil Pollution     Hybrid Journal   (Followers: 22)
Water, Air, & Soil Pollution : Focus     Hybrid Journal   (Followers: 9)
Waterlines     Full-text available via subscription   (Followers: 2)
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Weather, Climate, and Society     Full-text available via subscription   (Followers: 8)
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Wildlife Australia     Full-text available via subscription   (Followers: 2)
Wiley Interdisciplinary Reviews - Climate Change     Hybrid Journal   (Followers: 17)
Wiley Interdisciplinary Reviews : Energy and Environment     Hybrid Journal   (Followers: 4)
William & Mary Environmental Law and Policy Review     Open Access   (Followers: 2)
World Environment     Open Access   (Followers: 1)
World Journal of Entrepreneurship, Management and Sustainable Development     Hybrid Journal   (Followers: 4)
World Journal of Environmental Engineering     Open Access   (Followers: 2)
World Journal of Environmental Research     Open Access  
Worldviews: Global Religions, Culture, and Ecology     Hybrid Journal   (Followers: 8)
Zoology and Ecology     Hybrid Journal   (Followers: 4)
气候与环境研究     Full-text available via subscription   (Followers: 1)

  First | 1 2 3 4     

Journal Cover Journal of Iron and Steel Research, International
  [SJR: 0.784]   [H-I: 16]   [6 followers]  Follow
    
   Full-text available via subscription Subscription journal
   ISSN (Print) 1006-706X
   Published by Elsevier Homepage  [2969 journals]
  • Rolling Contact Fatigue Properties of SAE 8620 Steel after Case
           Carburizing
    • Abstract: Publication date: July 2016
      Source:Journal of Iron and Steel Research, International, Volume 23, Issue 7
      Author(s): Yan-guang CAO, Le XU, Gou-qiang ZHANG, Jie SHI, Mao-qiu WANG
      Rolling contact fatigue (RCF) properties of SAE 8620 steel after case carburizing have been investigated under two contact stresses of 4.0 and 5.5 GPa. Results show that the RCF life ranges from 2.5 × 106 to 3 × 107 cycles under the contact stress of 5.5 GPa, while it can be more than 1 × 108 cycles under the contact stress of 4.0 GPa. The rated fatigue life L 10 (lives with the 10% failure) is also drastically shortened from 9.8 × 106 to 5.4 × 105 cycles when the contact stress is increased from 4.0 to 5.5 GPa. Theoretical calculations and fractographs show that the maximum shear stress and the contact area increase with increasing the contact stress, making RCF tend to occur earlier.


      PubDate: 2016-07-03T15:01:47Z
       
  • Weldability of 1000 MPa Grade Ultra-low Carbon Bainitic Steel
    • Abstract: Publication date: July 2016
      Source:Journal of Iron and Steel Research, International, Volume 23, Issue 7
      Author(s): Qing-mei JIANG, Xiao-qiang ZHANG, Li-qing CHEN
      Maximum hardness test in weld heat-affected zone (HAZ), oblique Y-groove cracking test and mechanical property test of welding joint of 1000 MPa grade ultra-low carbon bainitic steel were carried out, so as to research the weldability of the steel. The results show that the steel has lower cold cracking sensitivity, and preheating temperature of 100 °C can help completely eliminate cold cracks, generating good process weldability. The increase of preheating temperature can reduce the hardening degree of heat-affected zone. The strength of welding joint decreases and hardness reduces when heat inputs increase, and excellent mechanical properties can be obtained when low welding heat inputs are used. Fine lath bainites of different orientations combined with a few granular bainites that effectively split the original coarse austenite grains are the foundation of good properties.


      PubDate: 2016-07-03T15:01:47Z
       
  • Effects of γ-irradiation and Deformation Temperature on Tensile
           Properties of Pb-2 mass% Sb Alloy
    • Abstract: Publication date: July 2016
      Source:Journal of Iron and Steel Research, International, Volume 23, Issue 7
      Author(s): Gh MOHAMMED, S. EI-GAMAL
      Effects of γ-irradiation and deformation temperature (T) on the tensile properties of Pb-2 mass% Sb alloys were studied. The samples were annealed at 458 K for 2 h in air, then water quenched after they were γ-irradiated (the different doses were 0.5, 1.0, 1.5, and 2.0 MGy). The tensile properties were performed using stress-strain measurements at a constant strain rate (1.2 × 10−3 s−1) and at different T (303 − 393 K). It was found that at constant dose, the fracture stress (σF) decreases while the fracture strain (ɛF) increases as T increases. At particular T, σF increases while ɛF decreases with increasing dose. The strain-hardening exponent (n), which is the slope of the relation between ln(σ) and ln(ɛ) of the parabolic part of the stress-strain curve, was determined and its values increase as T increases and decrease as the dose increases. The value of the activation energy increases as the dose increases from 0.07 eV for un-irradiated sample to 0.1 eV for the 2 MGy-irradiated sample. These values are in accordance with that needed for dislocation movement and ordering process. An interpretation of the results was given, based on the creation of point and line defects due to γ-irradiation, and that results in a distribution of beta phase (Sb-phase), leading to a difficulty in the movement of dislocations, so there is an increase in alloy hardness.


      PubDate: 2016-07-03T15:01:47Z
       
  • Green Approach to Corrosion Inhibition of Mild Steel by Lignin Sulfonate
           in Acidic Media
    • Abstract: Publication date: July 2016
      Source:Journal of Iron and Steel Research, International, Volume 23, Issue 7
      Author(s): Muna A. ABU-DALO, Nathir A.F. AL-RAWASHDEH, Ahmed A. MUTLAQ
      The inhibition effect of lignin sulfonate against corrosion for mild steel in acidic solution has been examined by means of FTIR (fourier transform infrared spectroscopy), FAA (flame atomic absorption) spectroscopy, SEM (scanning electron microscope), EDS (energy dispersive X-ray spectroscopy), and mass loss techniques. The results revealed that lignin is a beneficial inhibitor for mild steel corrosion in acidic medium. It has been further found that Langmuir adsorption isotherm is obeyed by the tested lignin's adsorption over the surface of mild steel. The range of inhibition efficiency (IE) in 2 mol · L−1 HCl was found to be 75.88 % − 87.88% for Reax 88A, 10.72% − 60.32% for Reax 88B, and 51.32% − 63.03% for Reax 100M, after immersed at 298 K for 24 h time.


      PubDate: 2016-07-03T15:01:47Z
       
  • Effect of 0.5 mass% Cu Addition on Ductility and Magnetic Properties of
           Fe-6. 5Si Alloy
    • Abstract: Publication date: July 2016
      Source:Journal of Iron and Steel Research, International, Volume 23, Issue 7
      Author(s): Zhao-yang CHENG, Jing LIU, Wen-si CHEN, Jia-chen ZHU, Xi-feng LIN, Zhi-dong XIANG
      The effect of adding 0.5 mass% Cu on ductility and magnetic properties of Fe-6. 5Si (mass%) alloy was investigated. The alloys with and without 0.5 mass% Cu addition were warm rolled into thin sheets of thickness no more than 0.3 mm at temperature below 600 °C. It was found that the alloy with 0.5 mass% Cu addition was more easily warm rolled than Cu-free alloy. Tensile tests were carried out to further investigate this phenomenon, which confirmed that the ductility of the alloy with 0.5 mass% Cu addition was significantly higher than that of Cu-free alloy at 550 °C. Based on the results of transmission electron microscopy analysis, the ductility increase of the alloy with 0.5 mass% Cu addition was attributed to the effect of Cu on the promotion of dynamic recovery and suppression of long-range order in the alloy during warm rolling process. It was also observed that the iron loss was lower and inductance was higher for the alloy with 0.5 mass% Cu addition. Thus, it can be concluded that adding a suitably small amount of Cu would not only increase the ductility of Fe-6. 5Si alloy at warm rolling temperatures but also improve its magnetic properties.


      PubDate: 2016-07-03T15:01:47Z
       
  • Source and Control of Nitrogen for X70 Pipeline Steel
    • Abstract: Publication date: July 2016
      Source:Journal of Iron and Steel Research, International, Volume 23, Issue 7
      Author(s): Min WANG, Yan-ping BAO
      The effects of some key factors on nitrogen absorption during the smelting process of X70 pipeline steel were studied, and the source of nitrogen pick-up was analyzed to find the bottleneck for nitrogen control. A series of measures were put forward to decrease the nitrogen pick-up. The results indicated that an exponential relationship existed between the nitrogen absorption index and the free oxygen in molten steel. Nitrogen absorption index could decrease below 0.3 when free oxygen in molten steel was above 100 × 10−6 after tapping. For low sulfur killed steel, the nitrogen absorption ratio and sulfur content satisfied a linear relationship with a slope of −0.007. Low free-oxygen and sulfur were beneficial to the deep desulfurization during vacuum treatment. The contradiction of high desulfurization ratio and low nitrogen pick-up during LF process could be resolved by skimming oxidizing slag after tapping and making new high basicity top slag. After optimization, the average content of nitrogen in final product decreased from 46 × 10−6 to 35 × 10−6.


      PubDate: 2016-07-03T15:01:47Z
       
  • Microstructural Evolution and Performance of In-situ Ag-Ni Composite after
           Solidification under Electromagnetic Stirring and Deformation
    • Abstract: Publication date: July 2016
      Source:Journal of Iron and Steel Research, International, Volume 23, Issue 7
      Author(s): Lin ZHANG, Ke HAN, Tian-nan MAN, En-gang WANG, Xiao-wei ZUO
      The effect of electromagnetic stirring (EMS) on microstructure and performance of Ag-8 mass% Ni composite was investigated under both solidified and deformed conditions. Without EMS, the Ag matrix formed short, thick dendrites in the ingot; whereas with EMS, dendrites were long and slim. Ni phase mainly formed particles or ribbons, distributed along boundaries between dendrite arms. Cold drawing of the solidified Ag-Ni ingots, both with and without EMS, produced high strength in-situ metal-matrix composite (MMC) consisting of Ag matrix reinforced by Ni ribbons. EMS improved the ductility of the composite, consequently enhancing its drawability and strength. EMS also increased the electrical conductivity in both solidified ingots and deformed in-situ composite wires. In both cases, hardness and tensile strength remained high. A model based on a combination of the modified linear rule of mixtures and the Hall-Petch relationship was used to rationalize the tensile strength and hardness with respect to its fabrication parameters and the microstructure of Ag-Ni in-situ composite.


      PubDate: 2016-07-03T15:01:47Z
       
  • Microstructure and Wear Properties of Fe-based Amorphous Coatings
           Deposited by High-velocity Oxygen Fuel Spraying
    • Abstract: Publication date: July 2016
      Source:Journal of Iron and Steel Research, International, Volume 23, Issue 7
      Author(s): Gang WANG, Ping XIAO, Zhong-jia HUANG, Ru-jie HE
      Fe-based powder with a composition of Fe12.87 Cr13.98 Mo16.33 C13.91 B8.88 (at. %) was used to fabricate coatings by high-velocity oxygen fuel spraying. The effects of the spraying parameters on the microstructure and the wear properties of the Fe-based alloy coatings were systematically studied. The results showed that the obtained Fe-based coatings with a thickness of about 400 μm consisted of a large-volume amorphous phase and some nanocrystals. With increasing the fuel and oxygen flow rates, the porosity of the obtained coatings decreased. The coating deposited under optimized parameters exhibited the lowest porosity of 2.8%. The excellent wear resistance of this coating was attributed to the properties of the amorphous matrix and the presence of nanocrystals homogeneously distributed within the matrix. The wear mechanism of the coatings was discussed on the basis of observations of the worn surfaces.


      PubDate: 2016-07-03T15:01:47Z
       
  • Precipitation Behavior of FeTiP in Ti-added Interstitial Free High
           Strength Steels
    • Abstract: Publication date: July 2016
      Source:Journal of Iron and Steel Research, International, Volume 23, Issue 7
      Author(s): Juan JIA, Wei-wei ZHU, Xin-li SONG, Ze-xi YUAN
      The precipitation behavior of FeTiP in interstitial free high strength (IFHS) steels has been studied by using a transmission electron microscope (TEM). The results show that the TiC particles, appearing at earlier stage, are more stable than the FeTiP ones during recrystallization annealing at the two given temperatures (810 °C and 840 °C). Therefore, the FeTiP particles can only be observed in the steels with sufficient amount of Ti. There is a critical forming time for the FeTiP, which is between 90 – 120 s at 810 °C and 60 – 90 s at 840 °C. The precipitation of FeTiP involves two steps, i.e. the formation of FeTi precursors and the diffusion of P. The formier step determines the reliance of Ti content for the precipitation of FeTiP, whereas the latter step leads to the difference in the critical annealing time.


      PubDate: 2016-07-03T15:01:47Z
       
  • Growth Kinetics of Laves Phase and Its Effect on Creep Rupture Behavior in
           9Cr Heat Resistant Steel
    • Abstract: Publication date: July 2016
      Source:Journal of Iron and Steel Research, International, Volume 23, Issue 7
      Author(s): Zhi-xin XIA, Chuan-yang WANG, Chen LEI, Yun-ting LAL, Yan-fen ZHAO, Lu ZHANG
      The effects of Laves phase formation and growth on creep rupture behaviors of P92 steel at 883 K were studied. The microstructural evolution was characterized using scanning electron microscopy and transmission electron microscopy. Kinetic modeling was carried out using the software DICTRA. The results indicated Fe2 (W, Mo) Laves phase has formed during creep with 200 MPa applied stress at 883 K for 243 h. The experimental results showed a good agreement with thermodynamic calculations. The plastic deformation of laths is the main reason of creep rupture under the applied stress beyond 160 MPa, whereas, creep voids initiated by coarser Laves phase play an effective role in creep rupture under the applied stress lower than 160 MPa. Laves phase particles with the mean size of 243 nm lead to the change of creep rupture feature. Microstructures at the vicinity of fracture surface, the gage portion and the threaded ends of creep rupture specimens were also observed, indicating that creep tensile stress enhances the coarsening of Laves phase.


      PubDate: 2016-07-03T15:01:47Z
       
  • Evaluation on Fatigue Performance and Fracture Mechanism of Laser Welded
           TWIP Steel Joint Based on Evolution of Microstructure and Micromechanical
           Properties
    • Abstract: Publication date: July 2016
      Source:Journal of Iron and Steel Research, International, Volume 23, Issue 7
      Author(s): Li-li MA, Ying-hui WEI, Li-feng HOU, Chun-li GUO
      The fatigue performance and fracture mechanism of laser welded twinning induced plasticity (TWIP.) steel joint were investigated experimentally based on the evolution of microstructure and micromechanical properties. The optical microscopy was used to analyze the evolution of microstructure. The variation of composition and phase structure of fusion zone were detected by energy dispersive X-ray and X-ray diffraction spectrometers. The micromechanical behaviors of the various zones were characterized using nanoindentation. The static tensile test and high cycle fatigue test were performed to evaluate the mechanical properties of welded joint and base metal. The microstructures, tensile properties and fatigue strength of base metal as well as welded metal were analyzed. The fatigue fracture surfaces of base metal and welded joint were observed by means of scanning electron microscopy, in order to identify fatigue crack initiation sites and propagation mechanisms. Moreover, the fatigue fracture characteristics and mechanisms for the laser welded TWIP steel joints were analyzed.


      PubDate: 2016-07-03T15:01:47Z
       
  • Curvature and Residual Stress Analysis in Rotational Leveling of Bars
    • Abstract: Publication date: July 2016
      Source:Journal of Iron and Steel Research, International, Volume 23, Issue 7
      Author(s): Yong-qin WANG, Zhi-fang LIU, Hen-gan OU, Yuan-xin LUO, Xing-chun YAN
      Leveling process plays an important role in delivering the desired material properties and product standards. An analytical method for the rotational leveling process of bars was presented. First, each cross section of the bar in the leveling area was discretized with the roller gap-curvature relations established in both planes XY and XZ. Second, a numerical procedure with two steps was developed to simulate both pressing and leveling processes. This approach can be easily implemented to produce simulation results of the curvature and trajectory distributions during the leveling process, as well as the bending and residual stresses. It is found that curvature and trajectory distributions follow a sine-shape due to the characteristic of rotational movement, which also results in a helical pattern of residual stress after leveling. Based on the results obtained, it is also observed that the rotational movement is beneficial for adding the number of bending cycle. This is the reason why there are only a few pairs of rollers on the bar leveler.


      PubDate: 2016-07-03T15:01:47Z
       
  • Influence of Mechanical Activation on Acid Leaching Dephosphorization of
           High-phosphorus Iron Ore Concentrates
    • Abstract: Publication date: July 2016
      Source:Journal of Iron and Steel Research, International, Volume 23, Issue 7
      Author(s): De-qing ZHU, Hao WANG, Jian PAN, Cong-cong YANG
      High pressure roll grinding (HPRG) and ball milling were compared to investigate the influence of mechanical activation on the acid leaching dephosphorization of a high-phosphorus iron ore concentrate, which was manufactured through magnetizing roasting-magnetic separation of high-phosphorus oolitic iron ores. The results indicated that when high-phosphorus iron ore concentrates containing 54.92 mass % iron and 0.76 mass % phosphorus were directly processed through acid leaching, iron ore concentrates containing 55.74 mass% iron and 0.33 mass % phosphorus with an iron recovery of 84.64 % and dephosphorization of 63.79 % were obtained. When high-phosphorus iron ore concentrates activated by ball milling were processed by acid leaching, iron ore concentrates containing 56.03 mass % iron and 0.21 mass% phosphorus with an iron recovery of 85.65% and dephosphorization of 77.49 % were obtained. Meanwhile, when high-phosphorus iron ore concentrates activated by HPRG were processed by acid leaching, iron ore concentrates containing 58.02 mass% iron and 0.10 mass% phosphorus were obtained, with the iron recovery reaching 88.42% and the dephosphorization rate reaching 88.99%. Mechanistic studies demonstrated that ball milling can reduce the particle size, demonstrating a prominent reunion phenomenon. In contrast, HPRG pretreatment contributes to the formation of more cracks within the particles and selective dissociation of iron and P bearing minerals, which can provide the favorable kinetic conditions to accelerate the solid-liquid reaction rate. As such, the crystal structure is destroyed and the surface energy of mineral particles is strengthened by mechanical activation, further strengthening the dephosphorization.


      PubDate: 2016-07-03T15:01:47Z
       
  • Influences of Technological Parameters on Smelting-separation Process for
           Metallized Pellets of Vanadium-bearing Titanomagnetite Concentrates
    • Abstract: Publication date: July 2016
      Source:Journal of Iron and Steel Research, International, Volume 23, Issue 7
      Author(s): En-hui WU, Rong ZHU, Shao-li YANG, Ian MA, Jun LI, Jing HOU
      The smelting-separation process for metallized pellets of vanadium-bearing titanomagnetite concentrates was studied. The influences of smelting temperature, smelting time, and the basicity of the metallized pellet on vanadium and iron recovery were investigated. The characteristics of titanium slag were analyzed using X-ray diffraction, energy dispersive spectroscopy, and mineralographic microscopic analysis. The results demonstrate that appropriate increases in smelting temperature and smelting time can improve the vanadium and iron recovery from metallized pellets and are beneficial for the slag-iron separation. Although increasing the basicity of the metallized pellet can considerably improve the vanadium and iron recovery, the TiO2 grade of titanium slag was decreased. Under the optimal conditions, 90.17% of vanadium and 92.98% of iron in the metallized pellet were recovered, and the TiO2 grade of titanium slag was 55.01%. It was found that anosovite, augite, spinel, glassiness, and metallic iron were the main mineral phases of the titanium slag.


      PubDate: 2016-07-03T15:01:47Z
       
  • Viscosity and Structure Changes of CaO-SiO2-Al2O3-CaF2 Melts with
           Substituting Al2O3 for SiO2
    • Abstract: Publication date: July 2016
      Source:Journal of Iron and Steel Research, International, Volume 23, Issue 7
      Author(s): Guo-hua ZHANG, Yu-lan ZHEN, Kuo-chih CHOU
      During the smelting process of the high Al steels, the reaction between SiO2 in molten slag and dissolved aluminum in liquid steel always takes place. This aluminathermic reduction reaction will lead to the substitution of 1 mol SiO2 for 2/3 mol Al2O3. Therefore, the investigations about the influence of the ratio of Al2O3 to SiO2 on viscosity and structure changes of mould flux during this process are very necessary. The viscosity variation of CaO-SiO2-Al2O3-CaF2 melts was studied by changing compositions considering the aluminathermic reduction reaction. It was found that viscosity increased monotonously with gradually increasing the substitution extent. According to the Raman analysis, the substitution of Al2O3 for SiO2 leads to the decrease of non-bridging oxygen but the increase of bridging oxygen. Therefore, degree of polymerization and viscosity increase as the substitution extent increases. By comparing the measured viscosities with the model calculated values, it was found that both the recently developed Zhang's model and Roboud model could describe the viscosity variation behavior of CaO-SiO2-Al2O3-CaF2 melts very well.


      PubDate: 2016-07-03T15:01:47Z
       
  • Advances in Investigation of Fe-based Glass-forming Alloy Melts
    • Abstract: Publication date: June 2016
      Source:Journal of Iron and Steel Research, International, Volume 23, Issue 6
      Author(s): Hui GAO, Bang-shao DONG, Shao-xiong ZHOU
      Continuous precision casting is an important trend in modern industrialization. Clustering effects in glass-forming metallic liquids tremendously influence the properties of rapidly quenched ribbons; therefore, much attention has been paid to the study of Fe-based glass-forming melts at high temperatures. Recent investigations of these melts are categorized and reviewed. It is concluded that more efforts are still required to reveal the discipline of amorphization brought about by rapid quenching of Fe-based glass-forming melts.


      PubDate: 2016-06-15T05:54:59Z
       
  • Effect of Alloying Method on Microstructure and Wear Resistance of
           Fe-Cr-V-B Based Alloy
    • Abstract: Publication date: June 2016
      Source:Journal of Iron and Steel Research, International, Volume 23, Issue 6
      Author(s): Yu MA, Ying LIU, Jun LI, Hui ZHANG, Hao YANG
      The microstructure and wear behavior of Fe-Cr-V-B based alloy was investigated. Each of the specimens was characterized by metallographic techniques and hardness test. Phase analysis of alloy was performed by X-ray diffraction (XRD), scanning electron microscopy (SEM) and energy dispersive spectroscopy (EDS). The results showed that the microstructure of Fe-Cr-V-B based as-cast alloy containing 8.6 mass% V was composed of α-(Fe, Cr) solid solution, VC carbides, and V3B4 borides, whereas the as-cast alloy containing 24.8 mass% Cr was composed of α-(Fe, Cr) solid solution and V3B4, borides; the eutectic V3B4, borides mainly comprise M2B-type borides (M presents Fe and Cr). The existence of a large amount of V atoms affects the growth pattern of eutectic borides, which mainly display rod-like and grainy structure. The wear behavior of the experimental alloy has been investigated using pin-on-disk type friction and wear apparatus. The comparison of experimental results indicated that the relative wear resistance of the alloy containing 8.6 mass% V after destabilization heat treatment in a conventional furnace at 1373 K for 2 h was about six times higher than that of the high chromium (19 mass%) cast iron.


      PubDate: 2016-06-15T05:54:59Z
       
  • Corrosion Behavior of Cr Micro-alloyed Corrosion-resistant Rebar in
           Neutral Cl−-containing Environment
    • Abstract: Publication date: June 2016
      Source:Journal of Iron and Steel Research, International, Volume 23, Issue 6
      Author(s): Dan SONG, Wei SUN, Jin-yang JIANG, Han MA, Jian-chun ZHANG, Zhao-jun CHENG
      A new low-cost corrosion-resistant rebar (HRB400R) was designed and fabricated by Cr micro-alloying. The HRB400R rebar had uniform distribution of Cr element in ferrite grains. The corrosion behavior of the rebar in the neutral Cl−-containing environment was studied systematically, and the improved corrosion resistance of the HRB400R rebar was revealed. According to the corrosion-morphology observation and electrochemical monitoring during the constant immersion corrosion in the 3.5 mass% NaCl solution, the HRB400R rebar presented alleviated corrosion damage, nobler E corr, lower I corr, and larger R t values, and these phenomena were more remarkable in the initial corrosion period. The elevated electrode potential of the rebar, caused by the solid-solution of Cr micro-alloying in the ferrite grains, was the key to the corrosion-resistance improvement. The HRB400R rebar also presented much lower mass-loss rate in the salt spray corrosion test. Besides the elevated corrosion resistance of the matrix, the doping and enrichment of Cr element in the rust layer was another factor for the higher corrosion resistance, which retarded the penetration of aggressive medium through the rust layer.


      PubDate: 2016-06-15T05:54:59Z
       
  • Plasma Transferred Arc Surface Alloying of Cr-Ni-Mo Powders on Compacted
           Graphite Iron
    • Abstract: Publication date: June 2016
      Source:Journal of Iron and Steel Research, International, Volume 23, Issue 6
      Author(s): Ji-jun FENG, Chun-xu PAN, Liu-lin LU, Qi-wen HUANG, Hua-tang CAO
      A Cr-Ni-Mo overlayer was deposited on the surface of compacted graphite iron (CGI) by the plasma transferred arc (PTA) alloying technique. The microstructure of Cr-Ni-Mo overlayer was characterized by optical microscopy (OM), scanning electron microscopy (SEM) equipped with energy dispersive spectroscopy (EDS), and X-ray diffractometer (XRD). Results show that the cross-section consists of four regions: alloying zone (AZ), molten zone (MZ), heat affected zone (HAZ), and the substrate (SUB). The microstructure of AZ mainly consists of cellular γ-(Fe, Ni) solid solution, residual austenite and a network of eutectic Cr7C3 carbide while the MZ area has a typical feature of white cast iron (M3C-type cementite). The martensite/ledeburite double shells are observed in the HAZ. With decreasing the concentration of Cr-Ni-Mo alloys, the fracture mode changes from ductile in the AZ to brittle in the MZ. The maximum hardness of the AZ (450 HV0.2) is lower than that of the MZ (800 HV0.2). The eutectic M3C and M7C3 carbides increase the microhardness, while the austenite decreases that of the AZ.


      PubDate: 2016-06-15T05:54:59Z
       
  • Effect of Cr on Characteristic of Rust Layer Formed on Low Alloy Steel in
           Flow-accelerated Corrosion Environment
    • Abstract: Publication date: June 2016
      Source:Journal of Iron and Steel Research, International, Volume 23, Issue 6
      Author(s): Feng CHAI, Shan JIANG, Cai-fu YANG
      The flow-accelerated corrosion experiments were carried out to research the effect of Cr on the rust layers formed on the carbon steel and Cr-containing steel, as well as the structure of rust layer of the two experimental steels. The influence of Cr on the flow-accelerated corrosion resistance and the corrosion morphology of inner rust layer formed on the Cr-containing steel were studied by the methods of polarization curves, scanning electron microscope, transmission electron microscope, and X-ray photoelectron spectroscope. The distribution of Cr and its form of existence in the inner rust layer were analyzed. The results show that corroded mass loss of Cr-containing steel is lower than that of carbon steel and its inner rust layer is compact. Cr exists in the form of Fe2CrO4 and is enriched in the inner rust layer. This concentration could make the inner rust layer exhibit the tendency of amorphous. This phenomenon is related to fine Fe2CrO4. The inner rust layer becomes more compact because of the formation of fine Fe2CrO4, and the protectiveness of inner rust layer could be improved remarkably.


      PubDate: 2016-06-15T05:54:59Z
       
  • Relationship between Crystal Structure of Inclusions and Formation of
           Acicular Ferrites
    • Abstract: Publication date: June 2016
      Source:Journal of Iron and Steel Research, International, Volume 23, Issue 6
      Author(s): Zhi-min CUI, Li-guang ZHU, Yuan-liang LI, Qing-jun ZHANG, Chun-liang YAN, Wen-ling MO
      The formation mechanism of intragranular ferrites with acicular morphology was discussed. The ferrites were characterized by scanning electron microscopy. The results showed that the ferrites had an acicular structure with radial, symmetrical, and acicular laths, and that the inclusions were the nucleation sites of the intragranular acicular ferrites. Transmission electron microscopy (TEM) was used to characterize the inclusions. The results of TEM with energy dispersive spectroscopy and TEM-selected area electron diffraction indicated that the complex inclusions consisted of Ti-Al complex oxides and MnS. The jagged edges of the complex inclusions can be ascribed to the effects of the crystal structure. The stabilization energy U of the coordination polyhedron growth units varies with the type of connection according to the calculation results. A larger U corresponds to more stable growth units, which induces the preferentially oriented growth of inclusions, at which point acicular ferrites are formed.


      PubDate: 2016-06-15T05:54:59Z
       
  • Effects of TMCP Schedule on Precipitation, Microstructure and Properties
           of Ti-microalloyed High Strength Steel
    • Abstract: Publication date: June 2016
      Source:Journal of Iron and Steel Research, International, Volume 23, Issue 6
      Author(s): Xiang-dong HUO, Lie-jun LI, Zheng-wu PENG, Song-jun CHEN
      Using the similar compositions of the Ti-microalloyed high-strength steels produced by the thin-slab casting process of compact strip production (CSP), four thermo-mechanical control processes (TMCP) after the simulated thick-slab casting, i. e. the two hot rolling routes and the two cooling processes, were designed, aiming at achieving the same mechanical properties as the thin strip products. The final microstructures after the four TMCP processes were examined by optical microscope (OM), scanning electron microscope (SEM) and transmission electron microscope (TEM). The tensile properties and Charpy impact energy were measured correspondingly. Strain-induced TiC precipitation was found in the two-stage rolling route with the finish rolling temperature at low levels, leading to grain refinement due to the pinning effect during austenite recrystallization. Precipitation hardening in ferrite was observed when a period of isothermal holding was applied after hot rolling. It could be concluded that both finish rolling temperature and the subsequent isothermal holding temperature were crucial for the achieved strength level due to the combined effect of grain refinement and precipitation hardening. At the same time, it was found that the isothermal holding led to poor impact toughness because of remarkable precipitation hardening. Therefore, it was suggested that the precipitation kinetics of titanium carbides in both austenite and ferrite should be investigated in future.


      PubDate: 2016-06-15T05:54:59Z
       
  • Prediction and Experimental Validation of Forming Limit Curve of a
           Quenched and Partitioned Steel
    • Abstract: Publication date: June 2016
      Source:Journal of Iron and Steel Research, International, Volume 23, Issue 6
      Author(s): Xue-li GAO, Jun-ying MIN, Ling ZHANG, Quan-chao LI, Chang-wei LIAN, Jian-ping LIN
      Forming limit curve (FLC) is an effective tool to evaluate the formability of sheet metals. An accurate FLC prediction for a sheet metal is beneficial to its engineering application. A quenched and partitioned steel, known as QP980, is one of the 3rd generation advanced high strength steels and is composed of martensite, ferrite and a considerable amount of retained austenite (RA). Martensite transformation from RA induced by deformation, namely, transformation induced plasticity (TRIP), promotes the capability of work hardening and consequently formability. Nakazima tests were carried out to obtain the experimental forming limit strains with the aid of digital image correlation techniques. Scanning electron microscopy (SEM) was employed to examine the fracture morphologies of Nakazima specimens of the QP980 steel. The observed dimple pattern indicated that tensile stress was the predominant factor which led to failure of QP980 specimens. Therefore, maximum tensile stress criterion (MTSC) was adopted as the forming limit criterion. To predict the FLC of QP980 steel, Von-Mises yield criterion and power hardening law were adopted according to the tested mechanical properties of QP980 steel. Results were compared with those derived from other three representative instability theories, e. g. Hill criterion, Storen-Rice vertex theory and Bressan-Williams model, which shows that the MTSC based FLC is in better agreement with the experimental results.


      PubDate: 2016-06-15T05:54:59Z
       
  • Effect of Zn Vaporization on Wetting of Al-galvanized Steel in Cold Metal
           Transfer Process
    • Abstract: Publication date: June 2016
      Source:Journal of Iron and Steel Research, International, Volume 23, Issue 6
      Author(s): Qiao-li LIN, Gao-jun MAO, Qian HUANG, Rui CAO, Jian-hong CHEN
      The wetting of galvanized steel by molten Al alloys was studied in the cold metal transfer process by the sessile drop method using a high speed video camera. The wetting behavior can be divided into two typical cases, trending of non-wetting by using small wire feeding speed and wetting by using large wire feeding speed. The Leidenfrost effect is caused by the volatilization of Zn, which is responsible for the former case. The enhanced wettability of steel by Al and the weakening of the Leidenfrost effect are responsible for the latter case. Zn is the destabilizing factor for Al-steel joining that needs to be avoided by a reasonable design of process.


      PubDate: 2016-06-15T05:54:59Z
       
  • Effects of Temperature and Alloying Elements on γ Phase Fraction of
           Grain-oriented Silicon Steel
    • Abstract: Publication date: June 2016
      Source:Journal of Iron and Steel Research, International, Volume 23, Issue 6
      Author(s): Bing FU, Hai-jun WANG, Jian-xin YAN, Li XIANG, Sheng-tao QIU, Guo-guang CHENG
      The effects of temperature and alloying elements on γ phase fraction of grain-oriented silicon steel, which contained 2.97—3.42 mass% Si and 0.028—0.058 mass% C, were studied by microstructure observation and statistics. Furthermore, the quantitative relationships of temperature as well as C, Si, and Mn contents to γ phase fraction were obtained by numerical fitting. The experimental results show that γ phase fraction firstly increases with increasing temperature, reaches a maximum and then decreases in the temperature range of 900—1250 °C. The temperature corresponding to the maximum γ phase fraction is about 1150—1200 °C. Meanwhile, the γ phase fractions in steels at the same temperature have some differences because of different contents of various alloying elements. The verification results show that the values of γ phase fractions to C, Si, and Mn contents at the specific temperatures, which were obtained by multiple linear regression method, agree well with the measured values. In addition, the values of γ phase fractions to C, Si, and Mn contents in the temperature range of 900—1250 °C, which were obtained by binomial regression method, agree with the measured values when the contents of Mn and soluble Al are not more than 0.320 mass% and 0.034 mass%, respectively. The obtained equations can carry out the approximate prediction of γ phase fractions of grain-oriented silicon steels during the hot rolling process.


      PubDate: 2016-06-15T05:54:59Z
       
  • Effects of Nb and V on Microstructural Evolution, Precipitation Behavior
           and Tensile Properties in Hot-rolled Mo-bearing Steel
    • Abstract: Publication date: June 2016
      Source:Journal of Iron and Steel Research, International, Volume 23, Issue 6
      Author(s): Fu-ming LIU, Jian-jun WANG, Yu-jie LIU, R.D.K. MISRA, Chun-ming LIU
      Microstructural evolution, precipitation behavior, and tensile properties of four experimental Mo-bearing steels were studied to elucidate the effects of Nb and V on microstructural properties. The results indicated that the microstructure of hot-rolled steels consisted of polygonal ferrite and degenerate pearlite, and the morphology remained same after holding at 600 °C for 1 h. The smallest grain size was obtained in Nb-V-Mo containing steel, followed by Nb-Mo and V-Mo steels. Precipitation was less in the hot-rolled Mo-bearing steel. The maximum volume fraction of precipitates was obtained in Nb-V-Mo bearing steel, and the Nb-V-Mo complex carbonitrides were highly stable at 600 °C. In the Mo-bearing steel, the yield ratio was lowest at room temperature but highest at 600 °C, which was attributed to the precipitation of Mo carbides and drag effect of Mo solute on dislocation movement.


      PubDate: 2016-06-15T05:54:59Z
       
  • Influence of Residual Stress on Shape of Heavy-gauge, High-strength Steel
           Caused by Cooling Process after Hot Rolling
    • Abstract: Publication date: June 2016
      Source:Journal of Iron and Steel Research, International, Volume 23, Issue 6
      Author(s): Shui-ze WANG, Yong-lin KANG, Guo-ming ZHU, Wen LIANG
      The cooling process following hot rolling has a significant effect on the shape quality of a hot-rolled strip. The temperature and stress fields in the cooling process for a 14 mm thick strip with yield strength of 500 MPa grade were analyzed by the finite element method and actual test data, and the relationship between residual stress and shape defects was described. Subsequently, the small-crown rolling process and the coil slow cooling process were investigated. The results indicate that these processes improved the shape quality of the final product significantly.


      PubDate: 2016-06-15T05:54:59Z
       
  • Micro-alloying Effects of Yttrium on Recrystallization Behavior of an
           Alumina-forming Austenitic Stainless Steel
    • Abstract: Publication date: June 2016
      Source:Journal of Iron and Steel Research, International, Volume 23, Issue 6
      Author(s): Wu-xin ZHAO, Yuan WU, Sui-he JIANG, Hui WANG, Xiong-jun LIU, Zhao-ping LU
      Micro-alloying effects of yttrium on the recrystallization behavior of an alumina-forming austenitic (AFA) stainless steel were investigated. It was found that the grain growth kinetics of the steels doped with different amounts of yttrium (i. e., 0, 0.05 and 0.10 mass% Y) could be described by an Arrhenius type empirical equation. Added Y could interact with carbon and influence the morphology of carbides both inside grains and on the grain boundaries, thus altering the grain boundary mobility and grain growth. The steel doped with 0.05 mass% yttrium showed the highest activation energy of grain growth and the most retarded recrystallization behavior, which mainly resulted from the high density of fine carbides both inside grains and on the grain boundaries. However, excess addition of 0.10 mass% Y induced coarsening and then lowered density of carbides, which alleviated the yttrium effects. The results also manifest that micro-alloying of rare-earth elements such as yttrium is an effective way for controlling grain growth behavior during recrystallization of AFA steels, which may have great implications on engineering applications.


      PubDate: 2016-06-15T05:54:59Z
       
  • Formation Mechanism of Inclusion Defects in Large Forged Pieces
    • Abstract: Publication date: June 2016
      Source:Journal of Iron and Steel Research, International, Volume 23, Issue 6
      Author(s): Rong-sheng QI, Miao JIN, Xin-gang LIU, Bao-feng GUO
      Nonmetallic inclusions mixed into large forged metal objects destroy the continuity in the metal and affect the quality of the forged product. Research on how inclusions affect the plastic deformation of a matrix shows the significance of the formation mechanism of inclusion defects. For upset forging, the nonlinear finite element model was shown to be appropriate for the ingot hot-forging process by comparing the results with experiments involving plastic and hard inclusions inserted into the forged piece. The high-temperature stress-strain curves of MnS plastic inclusions were obtained experimentally. The results show how, during upsetting, the morphology of MnS plastic inclusions varies from spherical to ellipsoidal, until finally becoming flat in shape. The larger the inclusion is, the larger the degree of deformation of the inclusion is, and large inclusions enhance the risk of the final product failing to pass inspection for inclusion flaws. Strain significantly concentrates in the matrix near a hard inclusion. When the hard inclusion reaches a certain size, conical fractures form on both sides of the inclusion. To pass inclusion-flaw inspection and close hole defects to the extent possible, the flat-anvil upsetting is recommended. Finally, the inclusion-deformation state obtained by finite element simulation is verified experimentally.


      PubDate: 2016-06-15T05:54:59Z
       
  • Mechanism and Improvement of Straight Edge Seam Defect on Hot-rolled Plate
           Surfaces through Use of Chamfered Slabs
    • Abstract: Publication date: June 2016
      Source:Journal of Iron and Steel Research, International, Volume 23, Issue 6
      Author(s): Hui ZHANG, Peng HU, Ming-lin WANG
      To improve the straight edge seam defect on hot-rolled steel plates, the deformation and temperature distribution of rectangular slabs and chamfered slabs during rolling in a pilot rolling experiment were analyzed in detail using the finite element method. The results showed that the crease formed on the lateral side near the edge of the plate as a result of uneven stress during broadside rolling. The creases rose to the surface with unrestricted spread and evolved into a straight edge seam during the subsequent straight rolling. To eliminate the straight edge seam defect, chamfered slabs were developed and investigated for rolling. The use of the chamfered slabs provided two advantages for rolling: the distribution of the temperature near the edge was ameliorated, and the deformation shape was improved by the chamfered shape. As a result, the risk of forming a straight edge seam defect was reduced by the use of a chamfered slab.


      PubDate: 2016-06-15T05:54:59Z
       
  • Influence of Screw Design on Burden Descending Velocity and Particle
           Segregation in COREX Shaft Furnace
    • Abstract: Publication date: June 2016
      Source:Journal of Iron and Steel Research, International, Volume 23, Issue 6
      Author(s): Hai-feng LI, Heng ZHOU, Tao ZHANG, Yang YOU, Zong-shu ZOU, Wan-ren XU
      COREX shaft furnace (SF) is an industrial system that employs screw feeders; thus, the burden descending velocity and particle segregation in the SF can be directly affected by the design of screw. A three-dimensional actual size model of COREX-3000 SF was established using the discrete element method. Four types of burdens, including pellet, ore, flux and coke, were considered in this model. With this consideration, the effect of screw design on solid flow was investigated. Results showed that, in the base case, burdens fell primarily down from the first flight of the screw. The burden descending velocities were nearly uniform in the peripheral direction and decreased along the radial direction. In addition, the normalized particle size increased in the center area and decreased in the wall area. Reducing the flight diameter of screw benefited an even flow pattern and restrained the rolling tendency of burden from the edge to center areas. An optimized case was also proposed, in which a uniform solid flow profile could be obtained and the evenness of descending velocity along the radius could be greatly improved.


      PubDate: 2016-06-15T05:54:59Z
       
  • Stretch Bending of Z-section Stainless Steel Profile
    • Abstract: Publication date: June 2016
      Source:Journal of Iron and Steel Research, International, Volume 23, Issue 6
      Author(s): Zheng-wei GU, Meng-meng LÜ, Xin LI, Hong XU
      The stretch bending properties of a new Z-section stainless steel profile were investigated by simulation. The causes of the forming defects, such as section distortions and poor contour precision, were analyzed, and the corresponding controlling methods were proposed. The results show that the main forming defects for the stretch bending of the Z-section profile were the flange sagging, the sidewall obliquing inward, the bottom surface up warping, and the bad contour accuracy; the cross-section distortions were mainly induced by the shrinkage of the sidewall, which could be eliminated by increasing the sidewall height of the profile reasonably; the poor contour precision was mainly due to springback, which could be controlled by modifying the die surface based on the springback amount; for the investigated bending beam, the proper sidewall height compensation was 2 mm, and the suitable die surface modification amount was 1.2 times of the springback amount, when the elongation was 10% of the initial profile length. Stretch bending tests were conducted on a new type of die with adjustable bending surfaces, and high quality components were achieved, which verified the effectiveness of the defect controlling measures.


      PubDate: 2016-06-15T05:54:59Z
       
  • Phase Transformation of a Cold Work Tool Steel during Tempering
    • Abstract: Publication date: May 2016
      Source:Journal of Iron and Steel Research, International, Volume 23, Issue 5
      Author(s): Hong-xiao CHI, Dang-shen MA, Hui-xia XU, Wang-long ZHU, Jian-qing JIANG
      The hardness and microstructure evolution of a 8% Cr cold work tool steel during tempering for 40 h were investigated. Transmission electron microscope examinations showed that M3C carbides precipitated from supersaturated martensite after tempering at 350 °C. When the tempering temperature was higher than 520 °C, the M23C6 carbides precipitated to substitute for M3C carbides. After ageing at the temperature of 520 °C for 40 h, it was observed that very fine and dense secondary Mo2C precipitates were precipitated. Thus, it can be concluded that the early stage of Mo2 C-carbidc precipitation is like to be Gunier–Preston (G–P) zone formed by [Mo-C] segregation group which is responsible for the secondary hardening peak at 520 °C. Overageing at 700 °C resulted in recovery of martensitic microstructure and precipitation of M23C6 carbides. When ageing at 700 °C for more than 20 h, recrystallization occurred, which resulted in a change of the matrix morphology from martensitic plates to equiaxed ferrite. It was noticed that the size of recrystallized grain/subgrain was very fine, which was attributed to the pinning effect of M23C6 precipitates.


      PubDate: 2016-05-16T18:27:34Z
       
  • Influence of Vanadium on Fracture Splitting Property of Medium Carbon
           Steel
    • Abstract: Publication date: May 2016
      Source:Journal of Iron and Steel Research, International, Volume 23, Issue 5
      Author(s): Wei-jun HUI, Cheng-wei SHAO, Yong-jian ZHANG, Si-lian CHEN, Han DONG
      The fracture splitting property of medium carbon steel 37MnSiS microalloyed with V up to 0. 45% was investigated by using simulated fracture splitting test, for the development of new crackable medium carbon steel to manufacture high performance connecting rod. Conventional high carbon steel C70S6 was used for comparison. The results show that the volume fraction of both ferrite and V-rich M(C, N) particles increases, and the pearlite interla-mellar spacing decreases with increasing V content, which in turn results in gradual increase of strength and decrease of ductility and impact energy. The fracture splitting property of the tested steel could be improved significantly due to the increase of V content mainly through the precipitation hardening mechanism of fine M(C, N) precipitates. The fraction of brittle cleavage fracture in the crack initiation area increases noticeably with increasing V content and full brittle cleavage fracture surface could be obtained when V content was increased to 0. 45%. It is concluded that medium carbon steel with V content higher than about 0. 28% possesses not only comparable or even higher mechanical properties with those of conventional steel C70S6, but also excellent fracture splitting property, and therefore, is more suitable to fabricate high performance fracture splitting connecting rod.


      PubDate: 2016-05-16T18:27:34Z
       
  • Static Recrystallization Behavior of SA508-III Steel during Hot
           Deformation
    • Abstract: Publication date: May 2016
      Source:Journal of Iron and Steel Research, International, Volume 23, Issue 5
      Author(s): Ding-qian DONG, Fei CHEN, Zhen-shan CUI
      The static recrystallization behavior of SA508-III steel was investigated by isothermal double-hit hot compression tests at the deformation temperature of 950–1250 °C, the strain rate of 0. 01–1 s−1, and the inter-pass time of 1–300 s. The effects of deformation parameters, including forming temperature, strain rate, degree of deformation (pre-strain) and initial austenite grain size, on the softening kinetics were analyzed. Experimental results show that static recrystallization kinetics is strongly dependent on deformation temperature and degree of deformation, while less affected by the strain rate and initial grain size. The kinetics and microstructural evolution equations of static recrystallization for SA508-III steel were developed to predict the softening behavior and the statically recrystallized grain size, respectively. Based on the comparison between the experimental and predicted results, it is found that the established equations can give a reasonable estimate of the static softening behavior for SA508-III steel.


      PubDate: 2016-05-16T18:27:34Z
       
  • Effect of Spark Plasma Sintering Temperature on Electrochemical Properties
           of La0.82Mg0.18Ni3.50Co0.15 Alloy
    • Abstract: Publication date: May 2016
      Source:Journal of Iron and Steel Research, International, Volume 23, Issue 5
      Author(s): Xiao-ping DONG, Yan-rong PANG, Li-ying YANG, Qing WANG, Zhi-yuan LI
      Electrochemical properties of La0.82 Mg0.18 Ni3.50 Co0.15 alloys synthesized by spark plasma sintering (SPS) were investigated based on the electrochemical measurements, physical parameters and microstructure observation. The sintering behavior of La0.82 Mg0.18 Ni3.50 Co0.13 alloys at the temperatures of 900, 950 and 1000 °C is characterized by four stages, i.e., initial slight shrinkage, expansion, abrupt shrinkage and slight expansion. The maximum shrinkage displacement increases with increasing sintering temperature. All of the alloys consist of (La, Mg)2 (Ni, Co)7 phase; additionally, temperatures of 900 and 950 °C are beneficial to the formation of (La, Mg) (Ni, Co)3 phase, whereas the LaNi5 phase is easy to form in the alloy synthesized by SPS at 1000 °C. The electrochemical measurements indicate an evident change of the electrochemical performance of the alloys associated with increasing the sintering temperature. The discharge capacity of the alloys first increases and then decreases as sintering temperature rises, whereas their cycle stability clearly grows all the time. Furthermore, the charging-discharging potential difference and discharging efficiency both demonstrate that the electrochemical properties of the alloy electrodes first augment and then decline with increasing sintering temperature.


      PubDate: 2016-05-16T18:27:34Z
       
  • Evolution of Microstructure and Ordering in Rolling Process of Fe-6. 5
           mass% Si Alloy
    • Abstract: Publication date: May 2016
      Source:Journal of Iron and Steel Research, International, Volume 23, Issue 5
      Author(s): Hui LI, Yong-feng LIANG, Feng YE
      Fe-6. 5 mass% Si alloy is an excellent soft magnetic material with good application prospects. After rolling, the structure of the sheet is likely to be heterogeneous along the normal direction. The microstructure and ordering evolution in the thickness range of the sheets during hot-warm rolling process was studied by means of optical microscope and transmission electron microscope. The results show that dynamic recrystallization occurs in the surface parts during the hot and warm rolling processes, where the grains are equiaxed but have high density of dislocations due to the large deformation. The grains in the center part are elongated along the rolling direction. It is also found that in the hot rolled sheet, the center part has lower density of dislocations because of dynamic recovery. Meanwhile, this part has higher ordering content compared with the surface part, indicating that the high density of dislocations can inhibit the formation of ordering in the air cooling process after hot rolling. In the warm rolling process, both of the parts are deformed heavily. Large deformation destroys ordered phases and induces disordering. The ordering content is low in the whole warm rolled sheet.


      PubDate: 2016-05-16T18:27:34Z
       
  • Deformation Behavior of Fe-36Ni Steel during Cryogenic (123–173 K)
           Rolling
    • Abstract: Publication date: May 2016
      Source:Journal of Iron and Steel Research, International, Volume 23, Issue 5
      Author(s): Jian-jun ZHENG, Chang-sheng LI, Shuai HE, Ban CAI, Yan-lei SONG
      Microstructural evolution and mechanical properties of cryogenic rolled Fe-36Ni steel were investigated. The annealed Fe-36Ni steel was rolled at cryogenic temperature (123–173 K) with 20%–90% rolling reduction in thickness. The deformation process was accompanied by twinning at cryogenic temperature, and the mean thickness of deformation twins was about 200 nm with 20% rolling reduction. When the rolling reduction was above 40%, twinning was suppressed due to the stress concentration in the tested steel. Deformation microstructure of Fe-36Ni steel consisted of both twin boundaries and dislocations by cryogenic rolling (CR), while it only contained dislocations after rolling at room temperature (RT). The tensile strength of Fe-36Ni steel was improved to 930 MPa after 90% reduction at cryogenic temperature, while the tensile strength after 90% reduction at RT was only 760 MPa. More dislocations could be produced as the nucleation sites of recrystallization during CR process.


      PubDate: 2016-05-16T18:27:34Z
       
  • In-situ TEM Observation of Cementite Coarsening Behavior of 5Mn Steel
           during Tempering
    • Abstract: Publication date: May 2016
      Source:Journal of Iron and Steel Research, International, Volume 23, Issue 5
      Author(s): Ye XIA, Xi-nan LUO, Xiao-yan ZHONG, Hui-hua ZHOU, Cun-yu WANG, Jie SHI
      The cementite formation and coarsening behaviors of 0. 2 mass% C-5 mass% Mn steel during tempering at 500 °C were investigated by in-situ transmission electron microscope (TEM). In-situ TEM observation showed uniform distribution of cementite particles at the early stage of tempering in the rapidly heated (500 °C/s) sample. Elemental analysis confirmed that the cementite growth was dominated by Mn diffusion. During the cementite growth, the coarsening behavior of intragranular cementite was significantly controlled by the matrix diffusion, while that of the intergranular cementite was mainly governed by the boundary diffusion. The in-situ TEM observation revealed that the dislocation pipe diffusion of Mn took place during tempering, which accelerated the Mn diffusion between cementite particles. The coarsening rates of individual cementite particles were calculated based on the in-situ TEM observation.


      PubDate: 2016-05-16T18:27:34Z
       
  • Intelligent Control of Grate-kiln-cooler Process of Iron Ore Pellets Using
           a Combination of Expert System Approach and Takagi-Sugeno Fuzzy Model
    • Abstract: Publication date: May 2016
      Source:Journal of Iron and Steel Research, International, Volume 23, Issue 5
      Author(s): Gui-ming YANG, Xiao-hui FAN, Xu-ling CHEN, Xiao-xian HUANG, Zong-ping LI
      Grate-kiln-cooler has become a major process of producing iron ore pellets in China. Due to the diversity of the raw materials used and the multi-device multi-variable characteristics, this process still encounters with control problem. An attempt was proposed to deal with this issue. The three-device-integrated feature of the process was firstly analyzed to obtain control strategy, and then an intelligent control system using a combination of expert system approach and Takagi-Sugeno (T-S) fuzzy model was developed. Expert system approach was used to diagnose and remedy the abnormal conditions, while T-S fuzzy model was used to stabilize the thermal state. In the construction of T-S fuzzy rules, antecedents were identified by fuzzy c-mean clustering algorithm incorporated with subtractive clustering algorithm, and consequent parameters were identified by recursive least square algorithm. The control system was applied in a Chinese pelletizing plant and the application results demonstrated its effectiveness of stabilizing the thermal states within three devices.


      PubDate: 2016-05-16T18:27:34Z
       
  • Effect of Sodium Sulfate on Direct Reduction of Beach Titanomagnetite for
           Separation of Iron and Titanium
    • Abstract: Publication date: May 2016
      Source:Journal of Iron and Steel Research, International, Volume 23, Issue 5
      Author(s): En-xia GAO, Ti-chang SUN, Zhi-guo LIU, Chao GENG, Cheng-yan XU
      The effect of sodium sulfate on direct reduction of beach titanomagnetite, followed by magnetic separation, to separate iron and titanium was investigated. Direct reduced iron (DRI) with a high Fe content, low TiO2 content and low iron recovery was obtained after adding sodium sulfate. When the sodium sulfate dosage was increased from 0 to 10 mass %, the Fe content of the DRI increased from 90. 00 mass% to 93. 55 mass% and the TiO2 content decreased from 1. 27 mass% to 0. 70 mass%. The reduction mechanism of sodium sulfate was investigated by X-ray diffraction (XRD) and scanning electron microscopy (SEM) with energy dispersive spectrometer (EDS). Results revealed that the metallic iron grains in the reduced ore with sodium sulfate were larger than those in the ore without sodium sulfate. Sodium sulfate promoted the migration of iron as well as the accumulation and growth of metallic iron grains by low-melting-point carnegieite and troilite formed in the redox system. Low-melting-point carnegieite decreased the melting point of the system and then promoted liquefaction. Troilite could decrease the surface tension and melting point of metallic iron grains.


      PubDate: 2016-05-16T18:27:34Z
       
  • An Experimental Prototype of an Innovative Fluid-driven Electromagnetic
           Stirring Technique
    • Abstract: Publication date: May 2016
      Source:Journal of Iron and Steel Research, International, Volume 23, Issue 5
      Author(s): Bo WANG, Xiao-dong WANG, Yuri KOLESNIKOV, San ZHANG, Yan-qing TAN, Xian-zhao NA
      A new electromagnetic stirring technique that is driven by hydrodynamic forces was presented. This technique offers the following advantages. First, the stirrer can be immersed in the liquid metal, thereby significantly increasing the penetration depth of the electromagnetic forces and significantly improving the stirring efficiency; thus, this technique is particularly suitable for large-scale liquid metal. Second, under certain conditions, this technique can overcome difficulties that are encountered with traditional stirrers, such as accessing regions that are difficult to reach in working spaces with complex or narrow shapes. This stirrer also has a simpler structure than a traditional stirrer; thus, the design can be easily modified, and no external power supply is required. An experimental prototype was also presented for controlling the fluid flow rate, thereby controlling the electromagnetic force and velocity field of the driven liquid metal. The velocity distribution in a liquid GaInSn alloy under fluid-driven electromagnetic stirring was quantitatively measured using ultrasonic Doppler velocimetry (UDV). The primary results show that a remarkable velocity field has been achieved and that fluid-driven electromagnetic stirring is an effective means of stirring liquid metal. Finally, the potential applications of this technique in industry, along with key challenges, were discussed.


      PubDate: 2016-05-16T18:27:34Z
       
  • Carbothermic Reduction Mechanism of Vanadium-titanium Magnetite
    • Abstract: Publication date: May 2016
      Source:Journal of Iron and Steel Research, International, Volume 23, Issue 5
      Author(s): Shuang-yin CHEN, Xiao-jiao FU, Man-sheng CHU, Xi-zhe LI, Zheng-gen LIU, Jue TANG
      To achieve the high-efficiency utilization of vanadium-titanium magnetite (VTM), reduction experiments were conducted to determine the carbothermic reduction mechanism of VTM. Effects of volatile matter, temperature, time, and carbon ratio (molar ratio of fixed carbon in coal to oxygen in iron oxides of VTM) on reduction degree were investigated. Results show that reduction degree increases with increasing volatile matter in coal, temperature, time, and carbon ratio. Phase transformation, microstructure, and reduction path were analyzed by X-ray diffraction, scanning electron microscopy, energy-dispersive X-ray spectroscopy, and FactSage 6.0. The thermoravimetry-differential scanning calorimetry-quadrupole mass spectrometer method was used for kinetic analysis of the main reduction process. Results indicate that the kinetic mechanism follows the principle of random nucleation and growth (n=4), and the activation energy values at 600–900 and 900–1350 °C are 88.7 and 295.5 kJ/mol, respectively.


      PubDate: 2016-05-16T18:27:34Z
       
  • Effect of Mg Addition on Nucleation of Intra-granular Acicular Ferrite in
           Al-killed Low Carbon Steel
    • Abstract: Publication date: May 2016
      Source:Journal of Iron and Steel Research, International, Volume 23, Issue 5
      Author(s): Xiao-bing LI, Yi MIN, Zhe YU, Cheng-jun LIU, Mao-fa JIANG
      To verify the formation behaviors and mechanisms of intra-granular acicular ferrite (IAF) grains nucleated by Mg-Al-O in low carbon steel, the steels containing different Mg contents were refined in a vacuum induction furnace. The effect of Mg addition on the formation of IAF structure in Al-killed low carbon steel was investigated by optical microscope (OM) and scanning electron microscope with energy dispersive X-ray spectroscope (SEM-EDX). It reveals that the IAFs are only detected in Mg-added steels, and the volume fraction of IAF increases with the Mg concentration from 8×10−6 to 26×10−6. It shows that not only the MgO-Al2O3-MnS and MgO-Al2O3-P2O3 particles are the effective nucleation sites for IAF, but also the pure MgO · Al2O3 phase can promote the ferrite nucleation. A Mn-depletion zone (MDZ) is characterized adjacent to the MgO-Al2 O3-MnS, which is believed to be one of the possible mechanisms to explain the IAF nucleation. The MDZ around the MgO-Al2 O3-MnS inclusion would be induced by the MnS precipitation on the inclusion. It seems that the ability of Mg-containing inclusions to induce the nucleation of ferrite might be attributed to a new mechanism, i. e., the P-rich zone formed on a few Mg-Al-O inclusions might be another factor for promoting the IAF formation.


      PubDate: 2016-05-16T18:27:34Z
       
  • Micromechanical Behavior and Failure Mechanism of F/B Multi-phase High
           Performance Steel
    • Abstract: Publication date: May 2016
      Source:Journal of Iron and Steel Research, International, Volume 23, Issue 5
      Author(s): Cun-jiang TANG, Shi-long LIU, Cheng-jia SHANG
      The deformation and micro-voids formation mechanisms in ferrite/bainite (F/B) multi-phase steel with the volume fraction of bainite less than 50% were studied by numerical simulation and experimental observation. The results show that the micro-strain concentrates at the soft/hard phase (F/B) interface in the multi-phase steel, which should be correlated with the mechanism of incoordinate deformation. During the necking of the steel, the micro-voids initially form around the F/B interface, which also form in ferrite and bainite with the severe strain. The micro-voids in bainite are more dense and finer than those in ferrite. The failure mechanism of bainite is the coalescence of micro-voids, and the failure mechanism of ferrite is the growth and tearing of micro-voids. Due to the different failure mechanisms of ferrite and bainite, a suitable part of soft phase would be beneficial to the capability of anti-failure of F/B multi-phase steel during the ductile fracture.


      PubDate: 2016-05-16T18:27:34Z
       
  • Characterization of (Nb,Ti,Mo)C Precipitates in an Ultrahigh Strength
           Martensitic Steel
    • Abstract: Publication date: May 2016
      Source:Journal of Iron and Steel Research, International, Volume 23, Issue 5
      Author(s): Biao JU, Hui-bin WU, Di TANG, Ning DANG
      A study on ultrahigh strength steel plate subjected to novel thermo-mechanical control process was presented. The mechanical properties examination showed that the investigated steel exhibited excellent combination of ultra-high strength (2200 MPa) and toughness (26 J). The microstructure of the experimental steel was observed by scanning electron microscope and transmission electron microscope. Desired martensitic lath with width of about 180–230 nm was obtained. Nanostructured carbide precipitates with sizes of 20–50 nm, which contained Nb, Ti and Mo, were observed in the lath martensitic microstructure, and confirmed to be MC-type carbides with B1 structure by means of selected area electron diffraction. The compositional characteristics revealed by energy dispersive X-ray spectrometer mapping implied that the carbide forming elements Nb, Ti and Mo distributed in the precipitates evenly. Three-dimensional atom probe tomography reconstruction further indicated that Mo incorporated into the precipitates without enrichment in the carbide-matrix interface and probably substituted for Nb and Ti to form the (Nb,Ti,Mo)C carbides.


      PubDate: 2016-05-16T18:27:34Z
       
  • Hot Deformation Behavior and Processing Map of Spray Formed M3: 2 High
           Speed Steel
    • Abstract: Publication date: May 2016
      Source:Journal of Iron and Steel Research, International, Volume 23, Issue 5
      Author(s): Lin LU, Long-gang HOU, Hua CUI, Jin-feng HUANG, Yong-an ZHANG, Ji-shan ZHANG
      Hot deformation behavior of a new type of M3 : 2 high speed steel with niobium addition made by spray forming was investigated based on compression tests in the temperature range of 950–1150 °C and strain rate of 0.001–10s−1. A comprehensive constitutive equation was obtained, which could be used to predict the flow stress at different strains. Processing map was developed on the basis of the flow stress data using the principles of dynamic material model. The results showed that the flow curves were in fair agreement with the dynamic recrystallization model. The flow stresses, which were calculated by the comprehensive constitutive equation, agreed well with the test data at low strain rates (≤1 s−1). The material constant (α), stress exponent (n) and the hot deformation activation energy (Q HW) of the new steel were 0. 00615 MPa−1, 4.81 and 546 kJ ·mol−1, respectively. Analysis of the processing map with an observation of microstructures revealed that hot working processes of the steel could be carried out safely in the domain (T=1050–1150 °C, ɛ = 0.01–0.1 s−1) with about 33% peak efficiency of power dissipation (η). Cracks was expected in two domains at either lower temperatures (<1000 °C) or low strain rates (0.001 s−1) with different cracking mechanisms. Flow localization occurred when the strain rates exceeded 1 s−1 at all testing temperatures.


      PubDate: 2016-05-16T18:27:34Z
       
  • Modeling of Liquid Level and Bubble Behavior in Vacuum Chamber of RH
           Process
    • Abstract: Publication date: April 2016
      Source:Journal of Iron and Steel Research, International, Volume 23, Issue 4
      Author(s): Yi-hong LI, Yan-ping BAO, Rui WANG, Min WANG, Qing-xue HUANG, Yu-gui LI
      In the Ruhrstahl-Heraeus (RH) refining process, liquid steel flow pattern in a ladle is controlled by the fluid flow behavior in the vacuum chamber. Potassium chloride solution and NaOH solution saturated with CO2 were respectively used as a tracer to investigate the liquid and gas flow behaviors in the vacuum chamber. Principal component and comparative analysis were made to show the factors controlling mixing and circulation flow rate. The liquid level and bubble behavior in the vacuum chamber greatly affect fluid flow in RH process. Experiments were performed to investigate the effects of liquid steel level, gas flow rate, bubble residence time, and gas injection mode on mixing, decarburization, and void fraction. The results indicate that the mixing process can be divided into three regions: the flow rate-affected zone, the concentration gradient-affected zone, and their combination. The liquid steel level in the vacuum chamber of 300 mm is a critical point in the decarburization transition. For liquid level lower than 300 mm, liquid steel circulation controls decarburization, while for liquid level higher than 300 mm, bubble behavior is the main controlling factor. During the RH process, it is recommended to use the concentrated bubble injection mode for low gas flow rates and the uniform bubble injection mode for high gas flow rates.


      PubDate: 2016-05-05T10:35:22Z
       
  • Electroslag Remelting Withdrawing Technology for Offshore Jack-up Platform
           Rack Steel Manufacturing Process
    • Abstract: Publication date: April 2016
      Source:Journal of Iron and Steel Research, International, Volume 23, Issue 4
      Author(s): Xi-min ZANG, Tian-yu QIU, Wan-ming LI, Xin DENG, Zhou-hua JIANG, Hua SONG
      Offshore jack-up platform rack steel must exhibit high strength and toughness as well as excellent welding properties. A high-quality large ingot is a prerequisite for obtaining a high-performance rough part. The electroslag remelting withdrawing (ESRW) technology using a T-shaped mold and bifilar mode was introduced to replace casting technology. Numerical simulation of the ESRW process was performed to determine the distribution of the temperature and velocity fields and to determine the optimum process for producing rack steels. Several A514Q slab ingots with dimensions of 0. 32 m × 1. 40 m × 4. 00 m were produced using ESRW technology in an industrial plant. The industrial test indicated that slab ingots produced by the ESRW method exhibited uniform chemical compositions and compact macrostructures. A 115. 4 mm thick plate was produced from the rough ingot after 11 rolling passes. Samples were obtained from different positions in the steel plate to test the mechanical performance and examine the microstructure, and the results revealed that the properties of the steel plate satisfied ASTM standards. The ESRW process improved the tensile strength and toughness of the slab ingot, enabling significant improvements in the anisotropy and low temperature toughness, which are critical for the development of rack steel for offshore platforms.


      PubDate: 2016-05-05T10:35:22Z
       
  • Self-reduction Mechanism of Coal Composite Stainless Steel Dust Hot
           Briquette
    • Abstract: Publication date: April 2016
      Source:Journal of Iron and Steel Research, International, Volume 23, Issue 4
      Author(s): Sok-chol RI, Man-sheng CHU, Shuang-yin CHEN, Zheng-gen LIU, Hun HONG
      To efficiently recycle valuable metals such as chromium and nickel in stainless steel dust, self-reduction experiments were carried out to study the reduction mechanism of metal oxides in coal composite stainless steel dust hot briquette, which is defined as a CCSB here. Self-reduction of CCSB is proceeded by volatile matter and fixed carbon contained within CCSB. Experiments were performed to study the effects of temperature and carbon to oxygen (C/Ocoal) ratio on self-reduction of CCSB. At 1400 and 1450 °C, volatile matter in coal used for experiment could take the place of about 40% of fixed carbon in coal. Under the present experimental conditions, reduction product of chromium appears as FeCr2 O4, Cr2 O3, Cr7 C3, and [Cr] in turn during reduction. To evaluate the formation of metal nuggets in self-reduction process of CCSB, metal nuggets containing chromium and nickel were observed in outside of reduction products under various conditions, and thermodynamic equilibrium calculation was carried out for possible products and formation of molten metal by fixed carbon. SEM and EDS analyses were made for metal nugget and slag in reduced product. The results reveal that it is reasonable to achieve the metal nuggets at 1450 °C, 0. 8 of C/Ocoal ratio and 20 min of reduction time. The nugget formation can indicate one innovative process for comprehensive utilization of stainless steel dust.


      PubDate: 2016-05-05T10:35:22Z
       
 
 
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