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  Subjects -> ENVIRONMENTAL STUDIES (Total: 752 journals)
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ENVIRONMENTAL STUDIES (679 journals)            First | 1 2 3 4     

Showing 601 - 378 of 378 Journals sorted alphabetically
Scientific Journal of Environmental Sciences     Open Access   (Followers: 1)
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Soil and Sediment Contamination: An International Journal     Hybrid Journal   (Followers: 3)
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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  
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Wiley Interdisciplinary Reviews - Climate Change     Hybrid Journal   (Followers: 17)
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William & Mary Environmental Law and Policy Review     Open Access   (Followers: 2)
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  First | 1 2 3 4     

Journal Cover Journal of Iron and Steel Research, International
  [SJR: 0.661]   [H-I: 22]   [6 followers]  Follow
    
   Full-text available via subscription Subscription journal
   ISSN (Print) 1006-706X
   Published by Elsevier Homepage  [3039 journals]
  • Mechanical Properties and Fracture Behavior of Cu-Co-Be Alloy after
           Plastic Deformation and Heat Treatment
    • Abstract: Publication date: September 2016
      Source:Journal of Iron and Steel Research, International, Volume 23, Issue 9
      Author(s): Yan-jun ZHOU, Ke-xing SONG, Jian-dong XING, Zhou LI, Xiu-hua GUO
      Mechanical properties and fracture behavior of Cu-0. 84Co-0. 23Be alloy after plastic deformation and heat treatment were comparatively investigated. Severe plastic deformation by hot extrusion and cold drawing was adopted to induce large plastic strain of Cu-0. 84Co-0. 23Be alloy. The tensile strength and elongation are up to 476. 6 MPa and 18%, respectively. The fractured surface consists of deep dimples and micro-voids. Due to the formation of supersaturated solid solution on the Cu matrix by solution treatment at 950 °C for 1 h, the tensile strength decreased to 271. 9 MPa, while the elongation increased to 42%. The fracture morphology is parabolic dimple. Furthermore, the tensile strength increased significantly to 580. 2 MPa after aging at 480 °C for 4 h. During the aging process, a large number of precipitates formed and distributed on the Cu matrix. The fracture feature of aged specimens with low elongation (4. 6%) exhibits an obvious brittle intergranular fracture. It is confirmed that the mechanical properties and fracture behavior are dominated by the microstructure characteristics of Cu-0. 84Co-0. 23Be alloy after plastic deformation and heat treatment. In addition, the fracture behavior at 450 °C of aged Cu-0. 84Co-0. 23Be alloy was also studied. The tensile strength and elongation are 383. 6 MPa and 11.2%, respectively. The fractured morphologies are mainly candy-shaped with partial parabolic dimples and equiaxed dimples. The fracture mode is multi-mixed mechanism that brittle intergranular fracture plays a dominant role and ductile fracture is secondary.

      PubDate: 2016-09-07T02:39:03Z
       
  • Tensile Deformation Behavior of Fe-Mn-Al-C Low Density Steels
    • Abstract: Publication date: September 2016
      Source:Journal of Iron and Steel Research, International, Volume 23, Issue 9
      Author(s): Xiao-feng ZHANG, Hao YANG, De-Ping LENG, Long ZHANG, Zhen-yi HUANG, Guang CHEN
      Room temperature tensile tests of Fe-Mn-Al-C low density steels with four different chemical compositions were conducted to clarify the dominant deformation mechanisms. Parameters like product of strength and elongation, as well as specific strength and curves of stress-strain relations were calculated. The microstructures and tensile fracture morphologies were observed by optical microscope, scanning electron microscope and transmission electron microscope. The tensile behavior of low density steel was correlated to the microstructural evolution during plastic deformation, and the effects of elements, cooling process and heat treatment temperature on the mechanical properties of the steels were analyzed. The results show that the tensile strength of steels with different cooling modes is more than 1000 MPa. The highest tensile strength of 28Mn-12Al alloy reached 1230 MPa, with corresponding specific strength of 189. 16 MPa • cm3, • g−1, while the specific strength of 28Mn-10Al alloy was 178. 98 MPa • cm3, • g−1, and the excellent product of strength and elongation of 28Mn-8Al alloy was over 69. 2 GPa • %. A large number of ferrite reduced the ductility and strain hardening rate of the alloy, while the existence of κ carbides may improve the strength but weaken the plasticity. Some fine κ carbides appeared in the water-quenched specimen, while coarse κ carbides were observed in the air-cooled specimen. High temperature heat treatment improved the decomposition kinetics of γ phase and the diffusion rate of carbon, thus speeded up the precipitation of fine κ carbides. The dominant deformation mechanism of low density steel was planar glide, including shear-band-induced plasticity and microband-induced plasticity.

      PubDate: 2016-09-07T02:39:03Z
       
  • Corrosion Behavior of Welded Joints for Cargo Oil Tanks of Crude Oil
           Carrier
    • Abstract: Publication date: September 2016
      Source:Journal of Iron and Steel Research, International, Volume 23, Issue 9
      Author(s): Jin-shan WEI, Yan-chang QI, Zhi-ling TIAN, Yun PENG
      E32 grade corrosion resistant steel was welded with welding wires with three different S contents. The microstructure, mechanical properties, inclusions, and corrosion behavior of welded joint were investigated. The joint coupon corrosion test and potentiodynamic polarization test were carried out under the simulated corrosion environment of the inner bottom plates of cargo oil tanks. The pitting initiation and propagation mechanism of the weld metal were studied by scanning electron microscopy and infinite focus. The results indicated that the microstructures of three kinds of weld metals are all composed of acicular ferrite, ferrite side-plate and proeutectoid ferrite. The microstructure of heat-affected zone is composed predominantly of bainite. Joint welded with low S filler wire has good mechanical properties. S can decrease free corrosion potential and increase the corrosion tendency. The pitting initiation is oxide inclusion or sulfide-oxide inclusion complex. S can induce the formation of occluded area and promote the corrosion propagation. The chemical compositions of weld metal is similar to base metal, which can limit the galvanic corrosion between weld metal and base metal, and avoid formation of corrosion step.

      PubDate: 2016-09-07T02:39:03Z
       
  • Oxidation and Induration Characteristics of Pellets Made from Western
           Australian Ultrafine Magnetite Concentrates and Its Utilization Strategy
    • Abstract: Publication date: September 2016
      Source:Journal of Iron and Steel Research, International, Volume 23, Issue 9
      Author(s): Cong-cong YANG, De-qing ZHU, Jian PAN, Bin-zhi ZHOU, Hu XUN
      Western Australian magnetite concentrates normally have ultrafine granularity and much higher specific surface areas than Chinese magnetite concentrates owing to the significant pre-grinding and beneficiation for saleable iron grade. Such characteristics will inevitably affect the subsequent pelletization process. However, very few investigations have been done before. Thus, the oxidation and induration characteristics of pellet made from a Western Australian ultrafine magnetite concentrate were revealed by conducting routine preheating-roasting tests in an electric tube furnace and investigating the microstructure of fired pellets under an optical microscope in comparison with that of pellets made from typical Chinese magnetite concentrate. The liquidus regions of CaO-SiO2-Fe2CO3 and CaO-SiO2-Al2O3 ternary systems in air at various temperatures were calculated by FactSage software to explain the importance of liquid phase in the consolidation of fired pellets. The results show that pellet made from ultrafine magnetite concentrate possesses better oxidability and preheating performance than that made from Chinese magnetite concentrate. However, it has inferior roasting performance, usually requiring conditions of roasting at 1280 °C for at least 30 min to acquire sufficiently high compressive strength, which are attributed to higher temperature sensitivity caused by its smaller particle size and less formation of liquid phase because of low impurities like CaO and Al2O3 in raw materials. Correspondingly, its roasting performance can be significantly improved by blending with Chinese magnetite concentrates or increasing the pellet basicity (w CaO/w SiO2). By comprehensive evaluation, blending with Chinese iron ore concentrates is an appropriate way to utilize Western Australia ultrafine magnetite concentrates.

      PubDate: 2016-09-07T02:39:03Z
       
  • Constitutive Model of Warm Deformation Behavior of Medium Carbon Steel
    • Abstract: Publication date: September 2016
      Source:Journal of Iron and Steel Research, International, Volume 23, Issue 9
      Author(s): Hong-bin LI, Yun-li FENG, Tao YAN, En-lin YU
      The compressive behaviors of medium carbon steel specimens were investigated over a wide range of temperatures and strain rates using a Gleeble-3500 thermo-simulation machine. The results show that the flow stress increased with strain at first, and then gradually decreased after reaching a peak value. The flow stress softening rate at a high strain rate was larger than that at a low strain rate. The effects of deformation heating and friction on flow stress were analyzed. A new friction correction method, wherein the effect of strain on frictional coefficient was considered, was established here. The stresses revised by the new method deviated from the measured stresses with increasing strain. Meanwhile, the apparent frictional coefficient variation law with strain was obtained. The frictional coefficient increased as the strain increased and then slightly decreased after maintaining a constant value. The stress was corrected by considering deformation heating. The accuracy of the temperature correction method was verified using a special experiment. The results of the verification experiment show that the temperature correction method exhibited a good accuracy in calculating the variation of stress caused by deformation heating. A constitutive model considering strain was proposed here to describe the deformation behaviors. Compared with experimental data, the modified constitutive model exhibited a good accuracy as to constitutive correlation.

      PubDate: 2016-09-07T02:39:03Z
       
  • Thermal Behavior and Kinetics of Raw/Pyrolytic Wood and Coal Blends during
           Co-combustion Process
    • Abstract: Publication date: September 2016
      Source:Journal of Iron and Steel Research, International, Volume 23, Issue 9
      Author(s): Jian DING, Qing-cai LIU, Li-jun JIANG, Guo-qing LIU, Shan REN, Jian YANG, Lu YAO, Fei MENG
      The thermal properties of raw wood (RW) biomass, corresponding pyrolytic wood (PW) biomass, and their blends with anthracite coal (AC) were evaluated under combustion conditions with a thermogravimetric analysis (TGA) method. The blending ratios of the biomass with AC ranging from 0 to 100 mass% were taken into consideration to investigate the thermal behavior and kinetics of these blends during their co-combustion. For blends with different ratios of the RW to AC and 100% AC (100 AC), two distinct mass loss peaks related to the release or combustion process of the volatiles and the combustion of the char were noted. The addition of a higher ratio of RW or PW into AC can improve the combustion process of the blends. The thermal behavior of the RW/AC or PW/AC blends could not be characterized by a simple linear correlation of their pure material thermal behavior. With the RW/PW addition ratios varying from 25 mass% to 80 mass%, the apparent activation energy of the blends gradually decreased from 48. 46 to 34. 93 kJ/mol and from 82. 74 to 37. 81 kJ/mol for the RW/AC and PW/AC blends, respectively, with high correlation coefficient (R 2) values ranging from 0. 9956 to 0. 9984.

      PubDate: 2016-09-07T02:39:03Z
       
  • Tailoring of Mechanical Properties of Indirect Hot Stamping Steel Tubes by
           Laser Assisted Local Rapid Heating
    • Abstract: Publication date: September 2016
      Source:Journal of Iron and Steel Research, International, Volume 23, Issue 9
      Author(s): Mahmudun Nabi CHOWDHURY, Ju-ri KIM, Sung-tae HONG, Jin-wook JUNG, Heung-nam HAN, Sang-woo SO
      The effect of laser assisted local heating on the mechanical properties of a hot stamping steel tube was investigated. A heated region with a spiral shape was generated on the surface of the tube by combining the linear movement of the laser and the rotation of the tube. The results of axial crush tests show that the laser assisted local heating can be effectively used to modify the mechanical performance of the tube. A microstructural analysis confirms that the laser locally induces a martensitic phase transformation in the heated region and results in inhomogeneous microstructures along the length of the tube.

      PubDate: 2016-09-07T02:39:03Z
       
  • Effect of Rolling Process on Microstructure and Properties of 95CrMo Drill
           Steel
    • Abstract: Publication date: September 2016
      Source:Journal of Iron and Steel Research, International, Volume 23, Issue 9
      Author(s): Wei YU, Bao-sheng XIE, Ban WANG, Qing-wu CAI, Shi-xin XU
      In order to improve the strength and toughness of 95CrMo steel and explore a short flow process, a direct rolling process was employed, and the effect of finishing rolling process on microstructure and mechanical properties was investigated. The results show that, with the decrease of finishing rolling temperature, inter-lamellar spacing increases, the strength as well as hardness has a general increase, and secondary cementite is distributed uniformly but represents a remarkable decrease in size. Based on Hall-Petch type equation, an effective relationship of yield strength and pearlite structure parameters was established. The correlation coefficients between the measured and calculated strength were more than 0. 95, which indicated a high reliability of the relationship. By analyzing the individual strength contributions of pearlite structures, yield strength was found to have a more great dependence on pearlite inter-lamellar spacing than colony size.

      PubDate: 2016-09-07T02:39:03Z
       
  • Dynamic Response of Mold Oscillator Interacting with Steel Slabs
    • Abstract: Publication date: September 2016
      Source:Journal of Iron and Steel Research, International, Volume 23, Issue 9
      Author(s): Yonghui PARK, Hyunchul PARK
      A mathematical model to show the dynamic response of the mold oscillator was suggested. The model considered a frictional interaction between the mold oscillator and slab as several connected nodes. The governing equation considered the slab as a multi-degree-of-freedom (DoF) system, and included a hysteresis model to describe elastic-plastic behavior of the slab; the mold oscillator was given two DoF by utilizing pressure and displacement experiment data. Simulations indicate that the mold and slab execute various vibrations, and that mold oscillation marks are caused by a stick-and-slip phenomenon during intervals, in which the slab contacting the mold moves downward compared to the other slab (negative strip time). The slab shows the formation of mold oscillation marks to previous formation criterion equally when the mold velocity is faster than the casting speed about downward. The oscillation mark will grow up over 2 Hz exciting frequency with constant 4 mm stroke in simulations. Finally, the negative strip time was compared to the frictional force, hysteresis variable, and plastic force to investigate formation mechanism of the oscillation marks.

      PubDate: 2016-09-07T02:39:03Z
       
  • Microstructure Characteristic and Phase Evolution of Refractory Siderite
           Ore during Sodium-carbonate-added Catalyzing Carbothermic Reduction
    • Abstract: Publication date: September 2016
      Source:Journal of Iron and Steel Research, International, Volume 23, Issue 9
      Author(s): Shao-jun BAI, Meng WU, Ghao LÜ, Shu-ming WEN
      Thermodynamic analysis of refractory siderite ore during carbothermic reduction was conducted. Microstructure characteristics and phase transformation of siderite ore during sodium-carbonate-added catalyzing carbothermic reduction were investigated. X-ray diffraction (XRD), scanning electron microscopy and energy-dispersive analysis of X-rays were used to characterize the reduced samples. Results indicate that the solid reaction between FeO and SiO2 is inevitable during carbothermic reduction and the formation of fayalite is the main hindrance to the rapid reduction of siderite. The phase transformation of present siderite ore can be described as: siderite-magnetite-metallic iron, complying with the formation of abundant fayalite. Improving the reduction temperature (≤ 1050 °C) and duration is helpful for the formation and aggregation of metallic iron. The iron particle size in the reduced ore was below 20 μm, and fayalite was abundant in the absence of sodium carbonate. With 5% Na2CO3 addition, the iron particle size in the reduced ore was generally above 50 μm, and the diffraction intensity associated with metallic iron in the XRD pattern increased. The Na2O formed from the dissociation of Na2CO3 can catalyze the carbothermic reduction of the siderite. This catalytic activity may be mainly caused by an increase in the reducing reaction activity of FeO.

      PubDate: 2016-09-07T02:39:03Z
       
  • Magnetic Properties of Thermally Aged Fe-Cu Alloys with Pre-deformation
    • Abstract: Publication date: September 2016
      Source:Journal of Iron and Steel Research, International, Volume 23, Issue 9
      Author(s): Yi LI, Yuan-fei LI, Ben XU, Qiu-lin LI, Guo-gang SHU, Wei LIU
      Magnetic properties of thermally aged Fe-Cu alloys with pre-deformation have been evaluated to improve the understanding of using magnetic technology for the nondestructive evaluation (NDE) of irradiation embrittlement in reactor pressure vessel (RPV) steels. Fe-Cu alloys with and without pre-deformation were thermally aged at 500 °C and the changes in microstructure, mechanical properties and magnetic properties were determined. It is found that the strain-induced dislocations recover and the Cu-rich particles precipitate during the aging process, and the magnetic properties variation depends on the combined influence of these two factors. From the point of view of NDE, a fully tempered or annealed microstructure is favorable before RPV is put into service. These results improve the understanding of magnetic property evolution in actual RPV steels and help to develop NDE theory for irradiation embrittlement.

      PubDate: 2016-09-07T02:39:03Z
       
  • Unexpected Effect of Nb Addition as a Microalloying Element on Mechanical
           Properties of δ-TRIP Steels
    • Abstract: Publication date: September 2016
      Source:Journal of Iron and Steel Research, International, Volume 23, Issue 9
      Author(s): Sajad Gholami SHIRI, Seyed Ahmad Jenabali JAHROMI, Yahya PALIZDAR, Majid BELBASI
      The concept of microalloying was applied to the δ-TRIP (transformation-induced plasticity) steel to investigate the feasibility of increasing the mechanical properties and understanding the effect of microalloying on the morphology and structure of the steel. A hot rolled δ-TRIP steel with three different contents of Nb (0, 0. 03, 0. 07 mass%) was subjected to the microstructural and mechanical examination. The high Al and Si concentration in these steels guaranteed the presence of the considerable δ-ferrite phase in the microstructure after the casting and the subsequent hot rolling. The obtained results showed that Nb dramatically affects the microstructure, the dynamic recovery and recrystallization behavior, as well as the grain shape and thus the stability of austenite after the thermomechanical process of hot rolling. The results also revealed an unexpected effect of Nb on the mechanical properties. The addition of Nb to the δ-TRIP steel led to a significant decrease in the ultimate strength (from 1144 to 917 MPa) and an increase in ductility (from 24% to 28%). These unconventional results could be explained by the change in the steel microstructure. The work-hardening behaviors of all samples exhibit three stages of the work-hardening rate evolution. At the stage 2, the work-hardening rate of the studied steels increased, being attributed to the TRIP effect and the transformation of austenite to martensite.

      PubDate: 2016-09-07T02:39:03Z
       
  • Effects of Thermal Gradients and Rotational Flows on Grain Growth in 22 t
           Steel Ingots
    • Abstract: Publication date: September 2016
      Source:Journal of Iron and Steel Research, International, Volume 23, Issue 9
      Author(s): Zheng CHEN, Qi-jie ZHAI, Jie-yu ZHANG, Hong-gang ZHONG
      Heavy ingots are widely used in many industrial fields. The coarse grains formed during the process of ingot solidification influence the properties and fracture behaviors of the final products. The coarse grain growth was simulated under different thermal gradients. A 30Cr2Ni4MoV steel ingot was melted in a cubic crucible with dimensions of 15 cm × 10 cm × 23 cm, and the cooling conditions on each side of the crucible were controlled by different thermal curves. The influences of thermal gradients and rotational flows on grain growth in heavy steel ingots were then investigated both numerically and experimentally. The results showed that when the amplitude of the rotation angle was 60°, the metal was solidified under a reciprocating horizontal rotational condition when the angular velocity was 10 (°)/s or 20 (°)/s. As the thermal gradient increased, the lengths of the primary columnar grains increased, and the diameters of equiaxed grains decreased. When the direction of flow rotation was perpendicular to the direction of grain growth, the columnar grain zone was nearly eliminated, and the average diameter of equiaxed grains was 0. 5 mm.

      PubDate: 2016-09-07T02:39:03Z
       
  • Preparation and Metallurgical Analysis of High Activity Burnt Lime for
           Steelmaking
    • Abstract: Publication date: September 2016
      Source:Journal of Iron and Steel Research, International, Volume 23, Issue 9
      Author(s): Hua-qiang HAO, Yu-zhu ZHANG, Su-ju HAO, Chao-fa ZHANG, Wu-feng JIANG, Peng-hui CUI
      Burnt lime is an important material in steelmaking and its activity degree is a key factor for liquid steel quality. The burnt lime was made by the calcination of limestone in a high pressure electric furnace. The burnt lime mineralogical phases and micro-morphologies were characterized by X-ray diffraction (XRD) and field emission scanning electron microscopy (FE-SEM). The burnt lime activity degree was determined by acid-base titration, the burnt lime pore distribution was measured by mercury intrusion porosimetry (MIP), and the thermal effect of a mixture of burnt lime and slag was measured by differential scanning calorimetry (DSC). The results showed that the CaO grain size and pore size of burnt lime made under high pressure were larger than those of burnt lime made under atmospheric pressure. The CaO grain size and pore size increased and the laminate phenomenon also occurred clearly under high pressure. The activity degree of burnt lime made under high pressure was greater than that made under atmospheric pressure. The maximum activity degree was 437 mL for burnt lime made under a pressure of 0. 4 MPa. For the same ratio of CaO to SiO2, the melting temperature, hemisphere temperature and fluidity temperature of slag decreased with increasing burnt lime activity degree. The higher the activity degree the burnt lime had, the better the slag forming occurred. It was advantageous for 2CaO · SiO2 and 3CaO · SiO2 forming at lower temperatures if the burnt lime activity degree was increased.

      PubDate: 2016-09-07T02:39:03Z
       
  • Direct Reduction of High-phosphorus Oolitic Hematite Ore Based on Biomass
           Pyrolysis
    • Abstract: Publication date: September 2016
      Source:Journal of Iron and Steel Research, International, Volume 23, Issue 9
      Author(s): Dong-bo HUANG, Yan-bing ZONG, Ru-fei WEI, Wei GAO, Xiao-ming LIU
      Direct reduction of high-phosphorus oolitic hematite ore based on biomass pyrolysis gases (CO, H2, and CH4), tar, and char was conducted to investigate the effects of reduction temperature, iron ore-biomass mass ratio, and reduction time on the metallization rate. In addition, the effect of particle size on the dephosphorization and iron recovery rate was studied by magnetic separation. It was determined that the metallization rate of the hematite ore could reach 99. 35% at iron ore-biomass mass ratio of 1: 0. 6, reduction temperature of 1100 °C, and reduction time of 55 min. The metallization rate and the aggregation degree of iron particles increase with the increase of reduction temperature. The particle size of direct reduced iron (DRI) has a great influence on the quality of the iron concentrate during magnetic separation. The separation degree of slag and iron was improved by the addition of 15 mass% sodium carbonate. DRI with iron grade of 89. 11%, iron recovery rate of 83. 47%, and phosphorus content of 0. 28% can be obtained when ore fines with particle size of — 10 μm account for 78. 15%.

      PubDate: 2016-09-07T02:39:03Z
       
  • Chromium Recycling from Argon-oxygen Decarburization Dust in Hot Metal
           Pre-dephosphorization Process
    • Abstract: Publication date: September 2016
      Source:Journal of Iron and Steel Research, International, Volume 23, Issue 9
      Author(s): Dong-ping ZHAN, Yang-peng ZHANG, Zhou-hua JIANG, De-wei WANG, Hui-shu ZHANG
      The chromium recycling from the stainless steel dust of an argon-oxygen decarburization (AOD) furnace during a hot metal pretreatment process was investigated. Experiments at different temperatures or with different amounts of AOD dusts were carried out in a laboratory furnace equipped with MoSi2 heating elements and subsequently industrial experiments were conducted in a stainless steelmaking factory, in order to study the thermodynamic mechanism of C and Si reacted with Cr2O3 to get Cr from AOD dust. The results showed that the reaction between C and Cr2O3 occurred below 1572. 18 K. Although its reducing ability was weaker than that of Si, C enabled the Cr in Cr2O3 in the AOD dust to be recycled using the Si in the slag. By combining the AOD dust added in an earlier stage, the hot metal pretreatment slag added in a later stage could not only recycle Cr from AOD dust but also remove Si, S, and P. Higher hot metal temperatures resulted in higher Cr content and lower remained P concentration in the molten iron.

      PubDate: 2016-09-07T02:39:03Z
       
  • Evaluation of Burden Descent Model for Burden Distribution in Blast
           Furnace
    • Abstract: Publication date: August 2016
      Source:Journal of Iron and Steel Research, International, Volume 23, Issue 8
      Author(s): Ping ZHOU, Peng-yu SHI, Yan-po SONG, Kai-le TANG, Dong FU, Chenn Q. ZHOU
      Mathematical models for burden descending process have been applied to obtain whole burden structures in blast furnace, whereas the accuracy of those burden descent models has not been sufficiently investigated. Special evaluation method based on timeline burden profiles was established to quantitatively evaluate the error between experimental and modeled burden structures. Four existing burden descent models were utilized to describe the burden structure of a 1/20 sealed warm blast furnace. Input modeling conditions including initial burden profile, descending volumes in each time interval, and normalized descending velocity distribution were determined via special image processing technology. Modeled burden structures were evaluated combined with the published experimental data. It is found that all the models caught the main profile of the burden structure. Furthermore, the improved nonuniform descent model (Model IV) shows the highest level of precision especially when burden descends with unstable velocity distribution tendency. Meanwhile, the traditional nonuniform descent model (Model III) may also be desirable to model the burden descending process when the burden descending velocity presents a linear tendency. Finally, the uniform descent model (Model I) might be the first option for roughly predicting burden structure.

      PubDate: 2016-08-18T15:16:54Z
       
  • Wear Mechanism of Iron-based Alloy Coating by Arc Spraying
    • Abstract: Publication date: August 2016
      Source:Journal of Iron and Steel Research, International, Volume 23, Issue 8
      Author(s): Zeng-rong LI, De-yuan LI, Nan-nan ZHANG, He HUANG, Xin WANG
      The arc spraying technique was adopted to prepare three types of iron-based coatings including 08Mn2Si, 4Cr13, and 65Mn. Meanwhile, the metallurgical microscope and scanning electron microscope (SEM) were used to analyze the microstructure of these coatings. Besides, a DPT-5 dye penetrant was painted on the surface of the coatings to simulate the oil fluid, so as to observe its penetration in the pore structures. The MMU-5G end-face high-temperature wear tester was used to carry out wear-resistance tests on these coatings and give comparison with grey cast irons. The experimental results showed that the 4Cr13 coating exhibited the best wear resistance under oil batch lubrication condition. According to the study of these coating structures, it was discovered that three coatings presented topology-like structures due to the accumulation of flat particles on the matrices. Meanwhile, it was found that zonal oxides were mixed in particles with some unmolten particles, pores, and cracks. Besides, the larger pores were mutually connected by gap-like pores. The existence of FeO in the coating and the pore structures keep oil in acted antifriction effects.

      PubDate: 2016-08-18T15:16:54Z
       
  • Dilatometric Analysis of Irreversible Volume Change during Phase
           Transformation in Pure Iron
    • Abstract: Publication date: August 2016
      Source:Journal of Iron and Steel Research, International, Volume 23, Issue 8
      Author(s): Ren-jie ZHAO, Jian-xun FU, Yu-yuan ZHU, Ye-jin YANG, Yan-xin WU
      One assumption underlying the conventional dilatometrie analysis based on the lever rule is that the volume of the specimen changes isotropically during phase transformation, which conflicts with the irreversible length change shown in actual measurements. The contribution of this irreversible effect to the dilation data of pure iron upon heating and cooling was respectively quantified via conversion equations based on lattice parameters. A model considering the elastic strain and creep deformation was established for both the interpretation of the irreversible volume change and the discrepancy between the results measured by a dilatometer and a micrometer.

      PubDate: 2016-08-18T15:16:54Z
       
  • Influence of Spot Welding on Welding Fatigue Properties of CR340 Steel
           Joints
    • Abstract: Publication date: August 2016
      Source:Journal of Iron and Steel Research, International, Volume 23, Issue 8
      Author(s): Rui-bin GOU, Wen-jiao DAN, Wei-gang ZHANG
      Total 72 lapped specimens including six different kinds of CR340 steel structures were prepared to study the influence of the spot welding technology on their fatigue characteristics. Fatigue test and group method were employed and performed on each sample to obtain the fatigue experimental data of each structure under four stress levels. The results show that the spot welding technology had a notable impact on the fatigue performance of both the shear and tensile joints. It can significantly improve the fatigue strength of the structure, the consistency and repeatability of experimental data, as well as the stability and reliability of the structure under dynamic load environment. The shear spot welding structure demonstrates the best fatigue performance which is very important for wide application in engineering of this method.

      PubDate: 2016-08-18T15:16:54Z
       
  • Effects of Processing Variables on Microstructure and Yield Ratio of High
           Strength Constructional Steels
    • Abstract: Publication date: August 2016
      Source:Journal of Iron and Steel Research, International, Volume 23, Issue 8
      Author(s): Jian KANG, Cheng-ning LI, Xiao-lei LI, Jin-hua ZHAO, Guo YUAN, Guo-dong WANG
      The process of “controlled rolling+relaxation+ultra fast cooling (UFO)” for high strength constructional steel with low yield ratio was presented. Microstructure and corresponding relationship with low yield ratio were investigated. The results showed that the constructional steels with multiphase microstructure of bainitie ferrite, martensite-austenite (M-A) and lath bainite were obtained through the creative process. The grain size decreased with the decrease in finish rolling temperature, which enhanced the strength by the grain refinement strengthening. The proper relaxation treatment promoted the bainitie ferrite lath width and the formation of blocky M-A constituent. In addition, both the tensile and yield strength increased with the decrease in finish rolling temperature and UFC final temperature, but the yield strength increased more significantly than tensile strength, which caused the increase in yield ratio. By using the process of “controlled rollingh+relaxation+ultra fast cooling”, the excellent comprehensive mechanical properties of 780 MPa grade constructional steels of 12 — 40 mm in thickness were achieved.

      PubDate: 2016-08-18T15:16:54Z
       
  • Arc Behavior and Droplet Transfer of CWW CO2 Welding
    • Abstract: Publication date: August 2016
      Source:Journal of Iron and Steel Research, International, Volume 23, Issue 8
      Author(s): Zhi-dong YANG, Chen-fu FANG, Yong CHEN, Guo-xiang XU, Qing-xian HU, Xiao-yan GU
      Cable-type welding wire (CWW) CO2 welding is an innovative process arc welding with high quality, high efficiency and energy saving, in which CWW is used as consumable electrode. The CWW is composed of seven wires with a diameter of 1. 2 mm. One is in the center, while others uniformly distribute around it. The diameter of twisted wire is up to 3. 6 mm, which can increase the deposition rate significantly. With continual wire-feeding and melting of CWW, the formed rotating arc improved welding quality obviously. The arc behavior and droplet transfer were observed by the electrical signal waveforms and corresponding synchronous images, based on the high speed digital camera and electrical signal system. The results showed that the shape of welding arc changed from bell arc to beam are with the increase of welding parameter. The droplet transfer mode changed from repelled transfer, globular transfer to projected transfer in turn. Droplet transfer frequency increased from 18. 17 Hz to 119. 05 Hz, while the droplet diameter decreased from 1. 5 times to 0. 3 times of the CWW diameter.

      PubDate: 2016-08-18T15:16:54Z
       
  • An Innovative Approach to Separate Iron Oxide Concentrate from High-sulfur
           and Low-grade Pyrite Cinders
    • Abstract: Publication date: August 2016
      Source:Journal of Iron and Steel Research, International, Volume 23, Issue 8
      Author(s): Yon LI, Fu-chun ZHOU, Zhao-xin ZHOU, Zhi-han TIAN, Chao YANG, Xi-ke TIAN
      High-sulfur and low-grade pyritc cinders are the waste products of sulfuric acid manufacturing plants. Many valuable components, such as iron oxide, are contained in pyrite cinders and difficult to be separated and purified just via the high temperature roasting process. Considering this, an innovative method including water-washing, aqua regia leaching, hydrothermal alkali activation and acid-washing was developed. And the effects of different parameters on recovery efficiency of iron oxide were systematically investigated. The optimum parameters were proposed as follows: water rinse-leaching at room temperature for 5 — 20 min, and melting at 160 °C for 2. Oh with NaOH (concentration of 30 mass%), followed by leaching with aqua regia solution (3. 0 vol. %) for 1. 0 h. After the treatment, the content of iron oxides increased from 54. 3 to 96. 0 mass% with the recovery rate exceeding 85%. Meanwhile, calcium sulphate was recovered as the high value-added products by alkali extraction liquid. Furthermore, the phase transformation and microstructure of the samples in the process were studied by physicochemical methods to reveal the separation mechanisms of different components in the pyrite cinders.

      PubDate: 2016-08-18T15:16:54Z
       
  • A New Approach for Refining Carbide Dimensions in M42 Super Hard
           High-speed Steel
    • Abstract: Publication date: August 2016
      Source:Journal of Iron and Steel Research, International, Volume 23, Issue 8
      Author(s): Xue-feng ZHOU, Wang-long ZHU, Hong-bing JIANG, Feng FANG, Yi-you TU, Jian-qing JIANG
      Obtaining small carbides is crucial but difficult for high-speed steels. A new approach for refining carbide dimensions in M42 super hard high-speed steel by increasing cooling rate and spheroidizing treatment was proposed. The morphologies and properties of eutectic carbides formed at different cooling rates were investigated by means of scanning electron microscopy (SEM), energy dispersive spectroscopy (EDS), X-ray diffraction (XRD), transmission electron microscopy (TEM), electron back-scattered diffraction (EBSD) and differential scanning calorimeter (DSC). The results show that eutectic carbides change from a lamellar shape into a curved-rod shape as cooling rate increases. Despite different morphologies, the two carbides are both of M2C type with a hexagonal close-packed structure and display a single crystal orientation in one eutectic colony. The morphology of M2C mainly depends on the growing process of eutectic carbides, which is strongly influenced by cooling rate. Compared with lamellar carbides, M2C carbides with curved-rod shapes are less stable, and decompose into M6C and MC at lower temperatures. They are more inclined to spheroidize during heating, which ultimately and distinguishably refines the carbide dimensions. As small carbides are much easier to dissolve into matrices during austenization, the process described herein improves the supersaturation of alloying elements in martensite, which leads to an increment of hardness in M42 steel.

      PubDate: 2016-08-18T15:16:54Z
       
  • On-line Ladle Lining Temperature Estimation by Using Bounded Jacobian
           Nonlinear Observer
    • Abstract: Publication date: August 2016
      Source:Journal of Iron and Steel Research, International, Volume 23, Issue 8
      Author(s): G. PHANOMCHOENG, S. CHANTRANUWATHANA, P. CHARUNYAKORN
      The knowledge of transient temperature of the ladle wall is a key factor in optimizing energy consumption in steelmaking process. The transient temperature needs to be estimated. A nonlinear lumped parameter model was used to model the thermal dynamics of the ladle. Then, the bounded Jacobian nonlinear observer was utilized to estimate the temperature. With this method, the estimation model became a closed-loop model and the observer gains were obtained by solving linear matrix inequalities and simply implemented to the system. Comparison between the simulation and recorded data at a participating steel plant in Thailand showed that the nonlinear observer accurately estimated the temperature of the ladle lining. This estimated temperature was very useful in determining suitable tapping temperature for energy conservation and steel quality.

      PubDate: 2016-08-18T15:16:54Z
       
  • Desulfurization Behavior and Mechanism of CaO-saturated Slag
    • Abstract: Publication date: August 2016
      Source:Journal of Iron and Steel Research, International, Volume 23, Issue 8
      Author(s): Jian-fei XU, Fu-xiang HUANG, Xin-hua WANG
      To develop a high-efficiency desulfurizer for the production of pipeline steel with the LD-RH-CC process, the desulfurization efficiency and mechanism of CaO-saturated slag were studied using a vacuum-induction furnace and Si-Mo electric resistance furnace. The results show that the desulfurization ability for slag with a small amount of solid CaO was highly enhanced under conditions of satisfied kinetics. The desulfurization reaction of CaO-saturated slag depended on the liquid slag rather than the solid CaO, as sulfur was not detected inside the solid CaO. The desulfurization efficiency of CaO-saturated slag was also influenced by the amount of residual liquid slag and its sulfur absorption ability. The sulfur absorption ability of CaO-CaF2 slag was analyzed to be much higher than that of CaO-Al2O3-CaF2-(SiCO2) slag. Moreover, the effect of solid CaO on the desulfurization kinetics was evaluated and the application conditions of CaO-saturated slag were discussed.

      PubDate: 2016-08-18T15:16:54Z
       
  • Prediction of Maximum Section Flattening of Thin-walled Circular Steel
           Tube in Continuous Rotary Straightening Process
    • Abstract: Publication date: August 2016
      Source:Journal of Iron and Steel Research, International, Volume 23, Issue 8
      Author(s): Zi-qian ZHANG
      Cross-sectional ovalization of thin-walled circular steel tube because of large plastic bending, also known as the Brazier effect, usually occurs during the initial stage of tube's continuous rotary straightening process. The amount of ovalization, defined as maximal cross section flattening, is an important technical parameter in tube's straightening process to control tube's bending deformation and prevent buckling. However, for the lack of special analytical model, the maximal section flattening was determined in accordance with the specified charts developed by experienced operators on the basis of experimental data; thus, it was inevitable that the localized buckling might occur during some actual straightening operations. New normal strain component formulas were derived based on the thin shell theory. Then, strain energy of thin-walled tube (per unit length) was obtained using the clastic-plastic theory. A rational model for predicting the maximal section flattening of the thin-walled circular steel tube under its straightening process was presented by the principle of minimum potential energy. The new model was validated by experiments and numerical simulations. The results show that the new model agrees well with the experiments and the numerical simulations with error of less than 10%. This new model was expected to find its potential application in thin-walled steel tube straightening machine design.

      PubDate: 2016-08-18T15:16:54Z
       
  • Effects of Different Oxidants on HCl-based Pickling Process of 430
           Stainless Steel
    • Abstract: Publication date: August 2016
      Source:Journal of Iron and Steel Research, International, Volume 23, Issue 8
      Author(s): Qiong XIE, Pei-yang SHI, Cheng-jun LIU, Mao-fa JIANG
      To shorten the time required for the pickling process and to enhance the quality of ferritic stainless steel plates, the effects of oxidants including hydrogen peroxide (H2O2), potassium permanganate (KMnO4), and potassium chlorate (KClO3) on the pickling behavior in HCl-based electrolyte as well as the surface quality of hot-rolled and blasted 430 stainless steel (430-SS) were studied. Experiments were conducted using mass-loss tests, microstructure analyses, potcntiodynamic polarization curves, and electrochemical impedance spectroscopy measurements. The results showed that the addition of oxidants substantially accelerated the pickling process of 430-SS by enhancing the cathodic reaction rate and reducing the charge transfer resistance. In electrolytes comprising 5 — 8 mass% HCl at a temperature of 40 — 60 °C and at the same concentration within the range from 0 to 2 mass%, H2O2 was demonstrated to be superior to KMnO4 and KClO3 in accelerating the pickling process. The surface quality of 430-SS pickled in the presence of H2O2 was better than those of specimens pickled in the presence of KMnO4 and KClO3 when the removal of the oxide layer, intergranular corrosion, and surface roughness were collectively considered. When 1 mass% H2O2 was added, the mass loss rate of 430-SS was increased by 629% and no residual oxide layer or intergranular corrosion was observed on the surface of the steel; in addition, the roughness was only 1. 7 μm. H2O2 was determined to be a better oxidant than KMnO4 and KCIO.3 when the pickling process, surface quality, solution recycling, and environment protection were considered as a whole.

      PubDate: 2016-08-18T15:16:54Z
       
  • Numerical Simulation and Experimental Study of an Ultrasonic Waveguide for
           Ultrasonic Casting of 35CrMo Steel
    • Abstract: Publication date: August 2016
      Source:Journal of Iron and Steel Research, International, Volume 23, Issue 8
      Author(s): Gen LIANG, Chen SHI, Ya-jun ZHOU, Da-heng MAO
      To achieve ultrasonic casting of 35CrMo steel, the waveguide unit for introducing ultrasound into liquid steel was studied numerically and experimentally. The structure and length of the ultrasonic waveguide were optimized by modal analysis. The simulation results showed that a T-shaped waveguide unit matched the vibrational system better than an L-shaped unit. The performance of T-shaped waveguide unit was optimized when the length of the ultrasound radiator was 135 mm. The performance of the T-shaped waveguide unit was investigated in ultrasonic casting experiments, and the effect of ultrasound on the microstructure of 35CrMo steel was examined. The experimental results showed that the T-shaped waveguide was able to successfully introduce ultrasound into the 35CrMo melt. In addition, the use of a silicon nitride ceramic radiator avoided high-temperature corrosion in the molten metal. The microstructure of the treated area was significantly refined and equiaxed grains were obtained. The results represented a novel method for ultrasonic casting of steel.

      PubDate: 2016-08-18T15:16:54Z
       
  • Effect of Scale Formation on Copper Enrichment Behavior in Continuously
           Cast Slab
    • Abstract: Publication date: August 2016
      Source:Journal of Iron and Steel Research, International, Volume 23, Issue 8
      Author(s): Nan WANG, Jin XU, Shan YU, Guang-zong ZHANG, Guang-hao CHEN, Min CHEN
      Copper enrichment behavior in continuously cast slab induced by scale formation during continuous cooling was experimentally investigated, and the effects of initial slab surface temperature and oxygen potential in atmosphere were discussed. The results showed that a loose scale adhered to the substrate was formed in H2O-N2 atmosphere at higher slab surface temperature compared to a gap formed between the scale and the steel substrate after continuous cooling in H2O-O-O2-N2 atmosphere. Under the condition of continuous cooling in H2O-N2 atmosphere, the copper enrichment occurred both within the loose scale and at the scale/steel interface with simultaneous Ni enrichment near the interface at higher slab surface temperature. The combined effects of the loose scale and nickel enrichment were thought to promote the back-migration of Cu-rich phase from the interface and occlusion within the scale layer. While in H2O-O2-N2 atmosphere, the Cu enrichment was found on the steel side and the formed gap prevented the migration of Cu to the scale.

      PubDate: 2016-08-18T15:16:54Z
       
  • Effects of Chromium Addition on Preparation and Properties of Bulk
           Cementite
    • Abstract: Publication date: August 2016
      Source:Journal of Iron and Steel Research, International, Volume 23, Issue 8
      Author(s): Bao-chao ZHENG, Zhi-fu HUANG, Jian-dong XING, Yi-yang XIAO, Xiao FAN, Yong WANG
      Bulk cementites with the Cr contents of 0, 3. 01, 6. 03, 8. 22, and 11. 51 mass% were prepared by mechanical alloying (MA) and spark plasma sintering (SPS). The results indicated that when the Cr content was low (3. 01 mass%), the phases were composed of cementite with a small amount of α-Fe at a sintering temperature of 1 173 K, but the microstructure became single-phase alloyed cementite as the Cr content was further increased. It showed that microaddition of Cr was beneficial for promoting the formation of cementite. Furthermore, the mechanical performance of cementite can be greatly affected by the variation of Cr content. The hardness, elastic modulus and elastic recovery presented a remarkably increasing tendency with the addition of Cr, and the maximum micro-hardness and elastic modulus values reached 1 070. 74 HV and 199. 32 GPa, respectively, which were similar to the precipitation phase (cementite) obtained by melting and casting techniques. Moreover, when the Cr content was below 11. 51 mass%, the crystal structure of Fe3C-type cementite would not change with increasing the Cr content. A Cr atom replaced an Fe atom in the lattice of the cementite, and voids appeared when Cr was doped into the cementite at content of about 11.51 mass%, causing the relative density to decrease.

      PubDate: 2016-08-18T15:16:54Z
       
  • Precipitation of μ Phase in Nickel-based Powder Metallurgy Superalloy
           FGH97
    • Abstract: Publication date: August 2016
      Source:Journal of Iron and Steel Research, International, Volume 23, Issue 8
      Author(s): Li-ming TAN, Yi-wen ZHANG, Jian JIA, Shou-bo HAN
      The precipitation behavior of topological close-packed (TCP) μ phase in powder metallurgy (P/M) nickel-based supcralloy FGH97 was investigated. The results showed that proper addition of solution strengthening elements, such as Co, Cr, W, Mo, improved tensile strength, while excessive addition of those elements facilitated the precipitation of μ phase, which seriously aggravated the plasticity of the P/M superalloy. For the heat-treated specimens, the relationship between critical aging time (when μ started to precipitate), aging temperature, and the average electron vacancy number of γ matrix was established.

      PubDate: 2016-08-18T15:16:54Z
       
  • Abrasive Wear Behaviors of Light-weight Austenitic Fe-24Mn-7Al-1C Steel
           and Mn13Cr2 Steel
    • Abstract: Publication date: August 2016
      Source:Journal of Iron and Steel Research, International, Volume 23, Issue 8
      Author(s): Shi-guang PENG, Ren-bo SONG, Zhi-dong TAN, Chang-hong CAI, Ke GUO, Zhong-hong WANG
      The impact abrasive wear behaviors of light-weight austenitic Fe-24Mn-7Al-1C steel with increasing impact wear conditions were studied by comparing with the modified Had field (Mn13Cr2) steel. Wear tests were performed with the MLD-10 abrasive wear testing machine. Main parameters such as impact energy, impacting frequency and wear time were evaluated. To explore the abrasive wear behaviors under different impact energies, the parameters including mass loss, wear resistance and hardness were evaluated in detail. The microstructures of the steels were further analyzed using optical microscopy (OM), scanning electron microscopy (SEM), transmission electron microscopy (TEM) and X-ray diffraction (XRD). Results showed that the light-weight austenitic Fe-24Mn-7Al-1C steel had a better wear resistance than Mn13Cr2 steel under the impact energy tested. The wear resistance of light-weight austenitic Fe-24Mn-7Al-1C steel was about 1. 09 — 1. 17 times as high as that of Mn13Cr2 steel under low and medium impact energy (0. 5 —2.0 J) conditions, and l. 41 times under high impact energy (4. 0 J) condition. In Mn13Cr2 steel, the evolution of dislocation substructure with increasing impact energy showed typical stacking fault, interaction of twins and dislocations, as well as mechanical twins. The high work-hardening rate in Fe-24Mn-7Al-1C steel was caused by Taylor lattice and high density of dislocation tangles.

      PubDate: 2016-08-18T15:16:54Z
       
  • 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
       
  • 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
       
 
 
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