Subjects -> METALLURGY (Total: 59 journals)
Showing 1 - 10 of 10 Journals sorted alphabetically
Acta Metallurgica Slovaca     Open Access   (Followers: 2)
Advanced Device Materials     Open Access   (Followers: 6)
American Journal of Fluid Dynamics     Open Access   (Followers: 44)
Archives of Metallurgy and Materials     Open Access   (Followers: 9)
Asian Journal of Materials Science     Open Access   (Followers: 4)
Canadian Metallurgical Quarterly     Hybrid Journal   (Followers: 21)
Complex Metals     Open Access   (Followers: 2)
Energy Materials : Materials Science and Engineering for Energy Systems     Hybrid Journal   (Followers: 24)
Graphene and 2D Materials     Open Access   (Followers: 6)
Handbook of Ferromagnetic Materials     Full-text available via subscription   (Followers: 1)
Handbook of Magnetic Materials     Full-text available via subscription   (Followers: 2)
High Temperature Materials and Processes     Open Access   (Followers: 6)
Indian Journal of Engineering and Materials Sciences (IJEMS)     Open Access   (Followers: 11)
International Journal of Metallurgy and Alloys     Full-text available via subscription   (Followers: 2)
International Journal of Metals     Open Access   (Followers: 7)
International Journal of Minerals, Metallurgy, and Materials     Hybrid Journal   (Followers: 12)
International Journal of Mining and Geo-Engineering     Open Access   (Followers: 4)
Ironmaking & Steelmaking     Hybrid Journal   (Followers: 5)
ISIJ International - Iron and Steel Institute of Japan     Full-text available via subscription   (Followers: 26)
Izvestiya Vuzov. Poroshkovaya Metallurgiya i Funktsional’nye Pokrytiya (Proceedings of Higher Schools. Powder Metallurgy аnd Functional Coatings)     Full-text available via subscription   (Followers: 2)
JOM Journal of the Minerals, Metals and Materials Society     Hybrid Journal   (Followers: 35)
Journal of Advanced Joining Processes     Open Access  
Journal of Central South University     Hybrid Journal   (Followers: 1)
Journal of Cluster Science     Hybrid Journal  
Journal of Heavy Metal Toxicity and Diseases     Open Access  
Journal of Iron and Steel Research International     Hybrid Journal   (Followers: 11)
Journal of Materials & Metallurgical Engineering     Full-text available via subscription   (Followers: 2)
Journal of Materials Processing Technology     Hybrid Journal   (Followers: 21)
Journal of Metallurgical Engineering     Open Access   (Followers: 4)
Journal of Sustainable Metallurgy     Hybrid Journal   (Followers: 3)
Materials Science and Metallurgy Engineering     Open Access   (Followers: 7)
Metal Finishing     Full-text available via subscription   (Followers: 20)
Metallurgical and Materials Engineering     Open Access   (Followers: 7)
Metallurgical and Materials Transactions A     Hybrid Journal   (Followers: 42)
Metallurgical and Materials Transactions B     Hybrid Journal   (Followers: 32)
Metallurgical and Materials Transactions E     Full-text available via subscription   (Followers: 2)
Metallurgical Research & Technology     Full-text available via subscription  
Metallurgical Research and Technology     Full-text available via subscription   (Followers: 8)
Metallurgy and Foundry Engineering     Open Access   (Followers: 3)
Mining, Metallurgy & Exploration     Hybrid Journal  
Powder Diffraction     Full-text available via subscription   (Followers: 1)
Powder Metallurgy     Hybrid Journal   (Followers: 35)
Powder Metallurgy and Metal Ceramics     Hybrid Journal   (Followers: 7)
Powder Metallurgy Progress     Open Access   (Followers: 5)
Practical Metallography     Full-text available via subscription   (Followers: 6)
Rare Metals     Hybrid Journal   (Followers: 3)
Revista de Metalurgia     Open Access  
Revista del Instituto de Investigación de la Facultad de Ingeniería Geológica, Minera, Metalurgica y Geográfica     Open Access  
Revista Remetallica     Open Access   (Followers: 1)
Russian Metallurgy (Metally)     Full-text available via subscription   (Followers: 4)
Science and Technology of Welding and Joining     Hybrid Journal   (Followers: 8)
Soldering & Surface Mount Technology     Hybrid Journal   (Followers: 2)
Steel Times lnternational     Partially Free   (Followers: 19)
Transactions of the IMF     Hybrid Journal   (Followers: 14)
Transactions of the Indian Institute of Metals     Hybrid Journal   (Followers: 5)
Tungsten     Hybrid Journal  
Universal Journal of Materials Science     Open Access   (Followers: 3)
Welding in the World     Hybrid Journal   (Followers: 8)
Welding International     Hybrid Journal   (Followers: 11)
Вісник Приазовського Державного Технічного Університету. Серія: Технічні науки     Open Access  
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Journal of Iron and Steel Research International
Journal Prestige (SJR): 0.569
Citation Impact (citeScore): 1
Number of Followers: 11  
 
  Hybrid Journal Hybrid journal (It can contain Open Access articles)
ISSN (Print) 1006-706X - ISSN (Online) 2210-3988
Published by Springer-Verlag Homepage  [2656 journals]
  • Determination of real-time oxygen transfer rate based on an
           electrochemical method
    • Abstract: Abstract The interfacial oxygen transfer rate is one of the main factors to control the composition of alloys. The commonly employed method of studying the interfacial oxygen transfer rate is the chemical composition analysis; however, it is difficult to be studied in situ. Here, a new method of measuring the oxygen transfer rate at the gas–slag and slag–metal interfaces was reported based on electrochemical analyses. The interfacial oxygen transfer rate in the smelting process of Inconel 718 superalloy was investigated at 1723, 1773, 1823, and 1873 K. The experimental results show that the electrochemical method can measure the real-time oxygen content; hence, this method is promising in controlling the oxygen content in alloys. As the temperature increased, both the equilibrium oxygen content and the rate of oxygen absorption increased significantly, and the increase was the most obvious when the temperature was 1873 K. The possible reason is that the increase in temperature weakens the mass transfer resistance of the electric double layer at the interface, thus accelerating the oxygen transfer rate.
      PubDate: 2021-05-03
       
  • M 23 C 6 precipitation and Si segregation promoted by deep cryogenic
           treatment aggravating pitting corrosion of supermartensitic stainless
           steel
    • Abstract: Abstract The microstructure evolution and the pitting corrosion resistance of a supermartensitic stainless steel after deep cryogenic treatment process were clarified through X-ray diffraction, field emission scanning electron microscopy, transmission electron microscopy (TEM) and electrochemical methods. The results showed that the microstructure of supermartensitic stainless steel mainly consisted of reversed austenite, tempered martensite, and M23C6 carbides after tempering. The deep cryogenic treatment promoted the refinement of the martensite laths and the precipitation of the carbides in comparison with the traditional process. TEM analysis indicated that the segregation of Si atoms at the boundary was found at the interface between carbide and martensite. The pitting corrosion potential of the specimens subjected to deep cryogenic treatment decreased with the elevated tempering temperature, and the lowest pitting corrosion potential was found at the tempering temperature of 650 °C. The sensitivity of the pitting corrosion potential was attributed to the precipitation of M23C6 carbides and Si atoms segregation. Si atoms segregation engendered the formation of Cr-depleted zone near M23C6 and impeded the recovery of Cr-depleted zone.
      PubDate: 2021-05-01
       
  • Effect of Al 2 O 3 and MgO on crystallization and structure of CaO–SiO 2
           –B 2 O 3 -based fluorine-free mold flux
    • Abstract: Abstract The crystallization behavior and melt structure of the CaO–SiO2–B2O3-based fluorine-free mold flux were investigated. The results show that the crystallization of the mold flux was first inhibited and then promoted with the increase in Al2O3 content from 4 to 12 wt.%. However, it was enhanced by MgO in the range of 2–10 wt.%. The results of Fourier transform infrared spectroscopy and Raman spectroscopy showed that Al2O3 worked as a network former in the mold flux melt when its content was in the range of 4–8 wt.%, whereas it worked as the network breaker to provide O2− when its content was in the range of 8–12 wt.%. In addition, the combined effects from the charge compensation by Mg2+ and the network broken by O2− led to the increase in some typical T–O–T (Al–O–Al, B–O–B, etc.) and simpler structural units (Q0(Si), B–O− in the [BO2O−], etc.) when the MgO content was in the range of 2–6 wt.%. The continuous increase in O2− provided by the addition of MgO from 6 to 10 wt.% further depolymerized the network of the melt and finally caused fast crystallization.
      PubDate: 2021-05-01
       
  • Data-based flatness prediction and optimization in tandem cold rolling
    • Abstract: Abstract In cold rolling process, the flatness actuator efficiency is the basis of the flatness control system. The precision of flatness is determined by the setpoints of flatness actuators. In the presence of modeling uncertainties and unmodeled nonlinearities in rolling process, it is difficult to obtain efficiency factors and setpoints of flatness actuators accurately. Based on the production data, a method to obtain the flatness actuator efficiency by using partial least square (PLS) combined with orthogonal signal correction (OSC) was adopted. Compared with the experiential method and principal component analysis method, the OSC–PLS method shows superior performance in obtaining the flatness actuator efficiency factors at the last stand. Furthermore, kernel partial least square combined with artificial neural network (KPLS–ANN) was proposed to predict the flatness values and optimize the setpoints of flatness actuators. Compared with KPLS or ANN, KPLS–ANN shows the best predictive ability. The root mean square error, mean absolute error and mean absolute percentage error are 0.51 IU, 0.34 IU and 0.09, respectively. After the setpoints of flatness actuators are optimized, KPLS–ANN shows better optimization ability. The result in an average flatness standard deviation is 2.22 IU, while the unoptimized value is 4.10 IU.
      PubDate: 2021-05-01
       
  • General heat balance for oxygen steelmaking
    • Abstract: Abstract Energy balances are a general fundamental approach for analyzing the heat requirements for metallurgical processes. The formulation of heat balance equations was involved by computing the various components of heat going in and coming out of the oxygen steelmaking furnace. The developed model was validated against the calculations of Healy and McBride. The overall heat losses that have not been analyzed in previous studies were quantified by back-calculating heat loss from 35 industrial data provided by Tata Steel. The results from the model infer that the heat losses range from 1.3% to 5.9% of the total heat input and it can be controlled by optimizing the silicon in hot metal, the amount of scrap added and the post-combustion ratio. The model prediction shows that sensible heat available from the hot metal accounts for around 66% of total heat input and the rest from the exothermic oxidation reactions. Out of 34% of the heat from exothermic reactions, between 20% and 25% of heat is evolved from the oxidation of carbon to carbon monoxide and carbon dioxide. This model can be applied to predict the heat balance of any top blown oxygen steelmaking technology but needs further validation for a range of oxygen steelmaking operations and conditions.
      PubDate: 2021-05-01
       
  • Enhancement of glass-forming ability and thermal stability of a soft
           magnetic Co 75 B 25 metallic glass by micro-alloying Y and Nb
    • Abstract: Abstract Soft magnetic Co-based Co–Y–Nb–B bulk metallic glasses (BMGs) without Fe have been developed by micro-alloying Y and Nb into a Co75B25 alloy. First, addition of 3–4 at.% Y promotes the occurrence of glass transition and increases the supercooled liquid stability and magnetic softness. Co71.5Y3.5B25 metallic glass possesses a large supercooled liquid region (ΔTx) of 33 K and low coercivity (Hc) of 1.5 A/m. Subsequent alloying 2–4 at.% Nb into Co71.5Y3.5B25 alloy further enlarges ΔTx to 50 K, lowers Hc to 0.9 A/m, and enables the formation of BMGs with a critical sample diameter up to 2.0 mm. The alloying Nb causes the formation of complex (Co, Nb, Y)23B6 competing phase during crystallization and widens the melt undercooling during solidification, which improves the supercooled liquid stability and glass-forming ability, respectively. Co–Y–Nb–B BMGs also exhibit good soft magnetic and mechanical properties, i.e., low Hc of 0.9–1.2 A/m, relatively high saturation magnetic flux density of 0.36–0.57 T, high yielding strength of 3877–3930 MPa with plastic strain of 0.2%–0.3%, and high Vickers hardness of 1156–1201. The developed soft magnetic Co-based BMGs are promising for applications as structural and functional materials.
      PubDate: 2021-05-01
       
  • Effect of vanadium addition on microstructure and properties of Al 0.5 Cr
           0.9 FeNi 2.5 multi-principal alloys
    • Abstract: Abstract Al0.5Cr0.9FeNi2.5Vx (x = 0, 0.2, 0.4, 0.6, 0.8, 1.0) multi-principal alloys were prepared by vacuum arc melting. The effect of vanadium addition on its microstructure and properties was investigated. The results show that the alloys of all components exhibited an FCC single-phase structure. With the addition of vanadium, the microstructure of the alloy changed from dendrites to equiaxed crystals, the grains were remarkably refined, and the layered CrV phase was exhibited, which improved the properties of the alloy. The yield strength of the alloy was slightly improved, and the alloys with various components presented good plasticity. When V content reached 0.8, the yield strength was 600 MPa, and no fracture occurred. Friction–wear testing showed that the wear debris was reduced with the addition of V element. The sample with V element content of 0.4 had the best friction and wear performance. The surface grooves became shallow, the worn debris was less, and the wear mechanism was mainly abrasive wear. The polarisation curve showed that the alloy with V element content of 0.2 has the best corrosion resistance. The passivation interval reached 900 mV. The corrosion potential and the corrosion current density were − 496.299 mV and 2.759 μA/cm2, respectively.
      PubDate: 2021-05-01
       
  • Effects of different alloying elements M (M = Fe, Ni, Mn, Si, Mo, Cu,
           Y) on Cr 2 O 3 with Cl: a first-principles study
    • Abstract: Abstract Using the first-principles methods, the effects of different alloying elements M (M = Fe, Ni, Mn, Si, Mo, Cu, Y) on Cr2O3 with Cl adsorption are studied. The results show that the layer distance of all doped models has been widened to different degrees with Cl adsorption. When Mo or Y is doped into the passive film, the difference of layer distance is reduced to a certain extent. The interaction between alloying elements and Cl is studied by calculating the adsorption height, bond population and electron density difference. The results show that Mo and Y can inhibit Cl erosion and improve the corrosion resistance of passive film. Furthermore, we investigate the CrMoFe and CrMoY co-doped system with Cl adsorption. The calculations point out that when Mo and Y are doped together in the passive film, the corrosion resistance of the system is more prominent than that of CrMo, CrY and CrMoFe co-doping systems.
      PubDate: 2021-05-01
       
  • Numerical simulation of slag layer and its distribution on hot surface of
           copper stave based on ANSYS birth-death element technology
    • Abstract: Abstract The core of the long-life copper stave was to ensure the stability of the slag layer, and the uniform distribution of the slag layer was beneficial to restrict the generation of the overthick slag layer. A novel model for calculating the thickness and distribution of the slag layer in the part of copper stave was established based on the finite element theory through the ANSYS birth-death element technology. The distribution and thickness of the slag layer on the hot surface of copper stave were calculated and analyzed when the gas temperature and slag properties tended to be changed, which was applied to characterize the slag-hanging capability of copper stave with the changes of furnace conditions. It was shown that the thickness of hot surface slag layer in the part of copper stave decreased obviously while the temperature of stave body raised rapidly with increasing gas temperature. When the gas temperature was 1400 °C, the inlaid slag layer was gradually melted, and the maximum temperature of the stave body was closed to 120 °C. The change of gas temperature was very sensitive to the adherent dross capability of copper stave which would be enhanced by the promotion of slag-hanging temperature. However, when the slag-hanging temperature was 1150 °C and the gas temperature was lower than 1250 °C, the overthick slag layer was easily formed on the hot surface of the copper stave, and its stability was poor. The improvement in the thermal conductivity of slag could be conducive to the formation of the uniform and stable slag layer on the hot surface of copper stave, especially in the dovetail groove. When the thermal conductivity of the slag was greater than 1.8 W m−2 °C−1, the inlaid slag layer in the dovetail groove was not melted, although the gas temperature reached 1500 °C.
      PubDate: 2021-05-01
       
  • Effect of hydrogen addition on compression deformation behaviour of
           Ti–0.3Mo–0.8Ni alloy argon-arc welded joints
    • Abstract: Abstract The effect of hydrogen addition on compression deformation behaviour of Ti–0.3Mo–0.8Ni alloy argon-arc welded joint has been investigated. Evolution mechanism of hydrogen-induced flow stress was discussed in detail. The results show that with increasing hydrogen content, the stretching and bending extent of fully lamellar microstructures including α lamellas and acicular hydride continued to increase, the morphology of dynamic recrystallization (DRX) grains tended to change from approximately equiaxed to large lamellar shape, and the quantity of DRX grains and recrystallization degree of grains increased obviously. A large number of dislocations concentrated in the vicinity of the hydride. Steady stress was decreased continuously with increasing hydrogen content, while peak stress of the hydrogenated 0.12 wt.% H weld zone was decreased to the minimum value and then increased slowly. A slight decrease in flow stress of the hydrogenated 0.05 wt.% H weld zone was caused by limited increase in the volume fraction of softer β phase. Hydrogen-induced DRX of α phase and improved dislocation movement by strong interaction between the hydride and dislocation directly resulted in a sharp drop in flow stress of the hydrogenated 0.12 and 0.21 wt.% H weld zone. Solute hydrogen also finitely contributed to a sharp drop in flow stress of the hydrogenated 0.12 and 0.21 wt.% H weld zone by promoted local softening, which induced continuous DRX and more movable dislocations to participate in slipping or climbing. The reinforcement effect and plastic deformation of the hydride and solution strengthening of β phase induced by solute hydrogen finally led to the increase in flow stress of the hydrogenated 0.21 wt.% H weld zone in its true strain range from 0 to 0.36.
      PubDate: 2021-05-01
       
  • Vertical–horizontal coupling nonlinear vibration characteristics of
           rolling mill under mixed lubrication
    • Abstract: Abstract Considering the dynamic influence of the roll vibration on the lubricant film thickness in the rolling deformation area, nonlinear dynamic rolling forces related to film thickness in the vertical and horizontal directions were obtained based on the Karman’s balance theory. Based on these dynamic rolling forces and the mechanical vibration of the rolling mill, a vertical–horizontal coupling nonlinear vibration dynamic model was established. The amplitude–frequency equation of the main resonance was derived by using the multiple-scale method. At last, the parameters of the 1780 rolling mill were used for numerical simulation, and the time-domain response curves of the system's vibration displacement and lubricating film thickness under the steady and unsteady conditions were analyzed. The influences of parameters such as interface contact ratio, nonlinear parameters and external disturbances on the primary resonance frequency characteristics were obtained, which provided a theoretical reference for the suppression of rolling mill vibration.
      PubDate: 2021-05-01
       
  • Prediction of compressive strength based on visualization of pellet
           microstructure data
    • Abstract: Abstract In recent years, with the wide application of image data visual extraction technology in the field of industrial engineering, the development of industrial economy has reached a new situation. To explore the interaction between the pellet microstructure and compressive strength, firstly, the pellet microstructure needed for the experiment was obtained using a Leica DM4500P microscope. The area proportions of hematite, calcium ferrite, magnetite, calcium silicate and pore in pellet microstructure were extracted by visual extraction technology of image data. Moreover, the relationship between the area proportions of mineral components and compressive strength was established by backpropagation neural network (BPNN), generalized regression neural network (GRNN) and beetle antennae search-generalized regression neural network (BAS-GRNN) algorithms, which proves that the pellet microstructure can be used as the prediction standard of compressive strength. The errors of BPNN and BAS-GRNN are 5.13% and 3.37%, respectively, both of which are less than 5.5%. Therefore, through data visualization, we are able to discuss the connection between various components of pellet microstructure and compressive strength and provide new research ideas for improving the compressive strength and metallurgical performance of pellet.
      PubDate: 2021-05-01
       
  • Large eddy simulation of transient transport and entrapment of particle
           during slab continuous casting
    • Abstract: Abstract To investigate the transient transport and entrapment of argon bubbles and inclusions simultaneously during continuous casting, a 3D large eddy simulation model coupling molten steel flow, solidification and particle motion was constructed. In this model, momentum transfer between molten steel and argon bubbles was performed by two-way coupling. The predicted results indicate that argon bubble injection changed the flow pattern of molten steel and the inclusion motion in the liquid pool. Consequently, the inclusion capture near the solidifying front was changed. In addition, measurements of bubbles and inclusions in the obtained samples were performed by methods of optical microscope examination and galvanostatic electrolysis. The results show a favorable agreement between the model predictions and the measured results, which validate the mathematical model. Furthermore, the predicted results of the inclusion entrapment in the case with argon bubble injection are more compatible with the measurements than those in the case without argon bubble injection.
      PubDate: 2021-04-30
       
  • Viscoplastic constitutive model of a nickel-based superalloy under
           multiaxial loading conditions
    • Abstract: Abstract Based on Chaboche constitutive model, a viscoplastic constitutive model of nickel-based alloy under multiaxial loading is proposed by introducing Lemaitre damage model and non-proportional hardening factor. Lemaitre damage model can characterize the effect of microscopic defects on the fatigue behavior and non-proportional hardening factor is used to describe non-proportional hardening phenomenon. Subsequently, the stress–strain hysteresis loops at room and high temperatures under different loading conditions are simulated by the proposed constitutive model. Comparison between experiments and simulations confirms that the proposed model can reasonably predict the fatigue behavior of nickel-based alloy under different multiaxial loadings. At last, the fatigue life predictions under different multiaxial loadings are investigated, and comparison between experiments and simulations verifies the accuracy of the proposed model.
      PubDate: 2021-04-29
       
  • A CA-LBM model for simulating dendrite growth with forced convection
    • Abstract: Abstract A two-dimensional coupled model of the cellular automaton (CA) and the lattice Boltzmann method (LBM) was developed to simulate the solute dendrite growth of Fe–C–Mn–S alloy in the presence of forced convection. The model describes the transport phenomenon by the evolution of moving pseudo-particles distribution functions and utilizes the LBM to solve fluid flow and solute transport under forced convection numerically. Based on the solute field calculated by the CA technique, the dynamics of dendrite growth were determined by the previously proposed local solute balance method. The accuracy of the forced convection dendrite growth model was verified by comparing the CA-LBM model with Lipton–Glicksman–Kurz analytical model. It is revealed that the dendrite symmetry structure is destroyed compared to free diffusion, and the upstream arm is more developed than the downstream arm of the dendrite. The enriched solute segregates more at the downstream side than at the upstream side of the dendrite. The length of the upstream dendrite arm increases firstly and then becomes stable with the increase in the flow velocity, the dendrite necking is restrained, and the vertical dendrite arm becomes longer.
      PubDate: 2021-04-29
       
  • Physicochemical properties of coconut husk activated carbon modified by
           Fe(NO 3 ) 3 and Mn(NO 3 ) 2
    • Abstract: Abstract Fe-loaded activated carbon (AC) has high surface acidity and more active sites, while manganese-loaded AC has high oxygen content. Coconut husk AC modified by Fe–Mn was studied with the aim of revealing the modification mechanism. First, HNO3/AC was prepared using the nitric acid immersion method. Second, Fe–Mn/AC was prepared using the Fe(NO3)3 and Mn(NO3)2 sequential immersion. The effects of HNO3, Fe(NO3)3, and Mn(NO3)2 on the pore texture and surface chemical characteristics of carbon materials were examined by scanning electron microscopy, Brunauer–Emmett–Teller (BET) analysis, X-ray diffraction and Fourier-transform infrared spectroscopy. The surface topography, pore structure, active material, and functional groups of AC, HNO3/AC, and Fe–Mn/AC were systematically studied. The following results were obtained. The surface of HNO3/AC has more ditches and air voids; the micropores of HNO3/AC are deformed and flattened compared to those of AC. The surface of Fe–Mn/AC exhibits an accumulation phenomenon. MnFe2O4 and FeMn2O4 formed more pore structures. AC and HNO3/AC have numerous micropores. The higher loading quantity of Fe–Mn results in bigger specific surface. The active components of Fe–Mn/AC-1, Fe–Mn/AC-2, Fe–Mn/AC-3, and Fe–Mn/AC-4 are MnFe2O4, Mn0.43Fe2.57O4, Mn3O4, and α-Fe2O3, respectively. The surface functional groups of AC and HNO3/AC are oxygen-containing functional groups. The effect of Fe–Mn modifying conditions on functional group species is rare; however, Fe/AC has more oxygen-containing functional groups. These research findings can aid in the desulfurization and denitrification of the Fe–Mn/AC catalyst.
      PubDate: 2021-04-28
       
  • An efficient method for iron ore sintering with high-bed layer:
           double-layer sintering
    • Abstract: Abstract Poor permeability and low sintering productivity restrict the development of high-bed sintering. An efficient method of the double-layer sintering process (DLSP) was proposed to achieve high-bed sintering and solve the aforementioned problems. Theoretical calculation and sintering pot experiments were implemented to investigate the double-layer sintering process. Traditional sintering process and DLSP were compared in terms of sintering indices, metallurgical properties and morphology characterization. Under the condition of traditional sintering process, DLSP successfully realized fast velocity and highly productive sintering of 1000-mm high bed. After the sintering bed is charged and ignited twice, the air permeability of the bed has been greatly improved. Sintering time is shortened significantly by simultaneous sintering of the upper and lower feed layers. Under the condition of bed height proportion of 350/650 mm and pre-sintering time of 20 min, the yield, tumbler strength, productivity and solid fuel consumption are 69.96%, 65.87%, 1.71 t (m2 h)−1 and 56.71 kg/t, respectively. Magnetite, hematite, calcium ferrite and complex calcium ferrite are the main phases of DLSP products. The metallurgical properties of DSLP products meet the requirement of ironmaking. It indicates that DLSP is an effective method to solve the disadvantages of bad permeability and low sintering productivity in high-bed sintering.
      PubDate: 2021-04-23
       
  • Hot deformation behavior and processing map of low-alloy offshore steel
    • Abstract: Abstract The hot deformation behavior of a low-alloy offshore steel was systematically investigated within the temperature range of 850–1150 °C and strain rate range of 0.01–10 s–1, via hot compression testing. The hot working equation, grain size model and recrystallization kinetic models of the steel were developed by fitting the experimental data. The results show that the decrease in Zener–Hollomon Z-parameter value (the increase in deformation temperature and the decrease in strain rate) is beneficial for the occurrence of dynamic recrystallization, and the grain size can be refined by increasing the Z-parameter value within the deformation range of dynamic recrystallization. However, when the Z-parameter value is higher than 3.43 × 1016, dynamic recrystallization will be difficult to occur within the range of experimental deformation conditions. Additionally, processing maps at different strains were constructed. According to the processing map and microstructural analysis, the optimal hot working conditions of the studied steel are within the temperature range of 1000–1100 °C and strain rate range of 0.1–1 s−1, and a complete recrystallization microstructure with fine homogeneous grains could be obtained.
      PubDate: 2021-04-23
       
  • Hybrid optimization for charge planning problem in twin strands continuous
           casting production
    • Abstract: Abstract Charge planning is one of batching problems for steelmaking and continuous casting production, and its optimization will be conducive to subsequent cast planning. Charge planning problem in the twin strands continuous casting production was studied, where casting width of the odd strand might be different from that of the even strand. Considering the different widths in the twin strands, the resulting counterweights and the constraints of steelmaking and continuous casting, a multi-objective optimization model was established to minimize the number of charges, the number of scale pairs, the surplus and the upgrading costs of steel grades. Furthermore, a hybrid optimization algorithm combined with heuristic and mutation-based estimation of distribution algorithm was proposed to solve the model. Experiments were conducted on several groups of test data collected from practical production orders of Baosteel. The computational results demonstrate that the proposed algorithm can generate better solutions than the manual method. The proposed model and algorithm proved to be effective and practical.
      PubDate: 2021-04-21
       
  • Static recrystallization behavior of SA508Gr.4N reactor pressure vessel
           steel during hot compressive deformation
    • Abstract: Abstract The two-pass isothermal hot compression method was used to study the effect of different thermal deformation conditions on static recrystallization behavior in Ni–Cr–Mo series SA508Gr.4N low alloy steel with interval holding time ranging from 1 to 300 s, temperature ranging from 950 to 1150 °C, strain rate ranging from 0.01 to 1 s−1, true strains ranging from 0.1 to 0.2, and initial austenite grain size ranging from 175 to 552 μm. It can be concluded that the static recrystallization volume fraction gradually increases with the increase in the deformation temperature, strain rate, strain and pass interval, and the decrease in the initial grain size, which is mainly due to the increase in the deformation energy storage and dislocations. Moreover, strain-induced grain boundary migration is the nucleation mechanism for static recrystallization of SA508Gr.4N low alloy steel. Based on the stress–strain curve, the predicted value obtained from the established static recrystallization kinetics model is in good consistence with the experimental value, and the static recrystallization thermal activation energy of SA508Gr.4N steel was calculated as 264,225.99 J/mol.
      PubDate: 2021-04-13
       
 
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