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Optimizing the low-pressure carburizing process of 16Cr3NiWMoVNbE gear steel

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Journal of Materials Science & Technology 2019年第7期35卷 1218-1227页

作者： Haojie Wang Bin Wang Zhaodong Wang Yong Tian r.d.k.misra State key Laboratory of rolling and Automation Northeastern UniversityShenyang 110819China Laboratory for Excellence in Advanced Steel research Department of MetallurgicalMaterials and Biomedical EngineeringUniversity of Texas at El PasoEl PasoTX 79968USA

Compared with the traditional atm ospheric carburization, low-pressure carburization has the benefits of producing no surface oxidation and leaving fine, uniformly dispersed carbides in the carburized layer. However, the process param eters for low-pressure carburization of 16Cr3NiWMoVNbE steel have yet to be optimized. Thus, we use the saturation-value method to optimize these parameters for aviation-gear materials. Toward this end, the m icrostructure and properties of 16Cr3NiWMoVNbE steel after different carburization processes are studied by optical microscopy, scanning electron microscopy, transm ission electron microscopy, and electron probe microanalysis. Considering the saturated austenite carbon concentration, we propose a model of carbon flux and an alloy coefficient for low -pressure carburization to reduce the carbon concentration in austenite and avoid the surface carbide network. At the early stage of carburization (30 s), the gas-solid interface has a higher concentration gradient. The averaging method is not ideal in practical applications, but the carbon flux measured by using the segm ented average m ethod is 2.5 times that measured by the overall average method, which is ideal in practical applications. The corresponding carburization tim e is reduced by 60%. By using the integral average method, the actual carburization time increases, which leads to the rapid form ation of carbide on the surface and affects the entire carburization process. Nb and Wcombine with C to form carbides, which hinders carbon diffusion and consumes carbon, resulting in a sharp decrease in the rate of C diffusion in austenite (the diffusion rate is reduced by 52% for 16Cr3NiWMoVNbE steel). By changing the diffusion coefficient model and comparing the hardness gradient of different processes, the depth of the actual layer is found to be very similar to the design depth.

关键词： 16Cr3NiWMoVNbE steel Low-pressure carburizing Saturated carbon concentration Carbon flux

Uncovering Microstructure-Property relationship in Ni-Alloyed Fe-Mn-Al-C Low-density Steel Treated by Hot-rolling and Air-Cooling Process

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Acta Metallurgica Sinica(English Letters) 2024年第4期37卷 713-725页

作者： Xiaoliang Jia Guhui Gao Xiaolu Gui Chun Feng r.d.k.misra Bingzhe Bai School of Mechanical Electronicand Control EngineeringBeijing Jiaotong UniversityBeijing100044China CNPC Tubular Goods research Institute Xi’an710077China Laboratory for Excellence in Advanced Steel research University of Texas at El PasoEl PasoTX79968-0521USA School of Material Science and Engineering Key Laboratory of Advanced Materials of Ministry of EducationTsinghua UniversityBeijing100084China

This paper focuses on the relationship between the microstructure and tensile properties of Fe-Mn-Al-C low-density high-strength steel processes by hot-rolling and air-cooling process. The microstructure analysis reveals that the combination of hot-rolling and air-cooling results in the formation of heterogeneous structures comprising different-sized γ and B_(2) phases in the low-density steel with the addition of nickel (Ni). The addition of Ni promotes the formation of the B_(2) phase and induces the pinning of B_(2) phase particles at the γ grain boundaries. This pinning effect effectively hinders the growth of the γ grains, leading to grain refinement. The tensile test results demonstrate that LdS-5Ni (low-density steel, LdS) exhibits excellent high strength and ductility combination, e.g., a tensile strength of 1535 MPa, yield strength of 1482 MPa, and elongation of 23.3%. These remarkable mechanical properties are primarily attributed to the combined strengthening contributions of grain refinement and duplex nano-sized second-phase precipitation hardening.

关键词： Low-density steel Microstructure B_(2)phase κ-Carbide Tensile properties

High strength-superplasticity combination of ultrafine-grained ferritic steel:The significant role of nanoscale carbides

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Journal of Materials Science & Technology 2021年第24期83卷 131-144页

作者： J.W.Liang Y.F.Shen r.d.k.misra P.k.Liaw key Laboratory for Anisotropy and Texture of Materials(MOE) School of Materials Science and EngineeringNortheastern UniversityShenyang110004China The State key Lab of rolling&Automation Northeastern UniversityShenyang110819China Laboratory for Excellence in Advanced Steel research University of Texas at El PasoTX79968USA department of Materials Science and Engineering University of TennesseeKnoxvilleTN37996USA

There is currently a gap in our understanding of mechanisms that contribute to high strength and high plasticity in high strength UFG ferritic steel with nano-size Fe3 C carbides in situations that involve combination of various strain rates and high *** this regard,we describe the mechanistic basis of obtaining high strength-high plasticity combination in an ultrafine-grained(UFG)(~500±30 nm)ferritic steel with nano-size carbides,which sustained large plastic deformation,exceeding 100%elongation at a temperature significantly below 0.5 of the absolute melting point(Tm).To address the missing gap in our knowledge,we conducted a series of experiments involving combination of strain rate and temperature effects in conjunction with electron microscopy and atom probe tomography(APT).Strain rate studies were carried out at strain rates in the range of 0.0017-0.17 s^(-1)and at different temperatures from 25℃to 600℃.dynamic recrystallization occurred at 600℃,resulting in a significant decrease in yield and tensile ***,the UFG ferritic steels had an advantage in tensile strength(UTS)and elongation-to-failure(εf)at 600℃,especially at strain rate of 0.0017 s^(-1),with high UTSof 510 MPa and excellent low temperature(rplasticity(εf=110%).These mechanical properties are significantly superior compared to similar type of steels at identical temperature.A mechanistic understanding of mechanical behavior of UFG ferritic steels is presented by combining the effect of strain rate,temperature,and nano-size carbides.

关键词： UFG ferritic steel Strain rate Temperature Nano-size precipitate Low temperature superplasticity

Hot deformation Behavior and Processing Maps of a Medium Manganese TrIP Steel

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Acta Metallurgica Sinica(English Letters) 2019年第8期32卷 1021-1031页

作者： Ning Yan Hong-Shuang di Hui-Qiang Huang r.d.k.misra Yong-Gang deng State key Laboratory of rolling and Automation Northeastern UniversityShenyang 110819China Laboratory for Excellence in Advanced Steel research Department of MetallurgicalMaterials and Biomedical EngineeringUniversity of Texas El PasoEl PasoTX 7996&USA

The hot deformation behavior of a medium-Mn steel was studied in terms of hot compression flow curves in the temperature range of 850–1050 ℃ and strain rates of 0.05–10 *** thermo-mechanical analysis was carried out and suggested that the microstructure during deformation was completely austenite which had high tendency for dynamic recrystallization(drX).The flow behavior was characterized by significant flow softening at deformation temperatures of 950–1050 ℃ and lower strain rates of 0.05–5 s-1, which was attributed to heating during deformation, drX and flow instability.A step-by-step calculating procedure for constitutive equations is *** verification of the modified equations indicated that the developed constitutive models could accurately describe the flow softening behavior of studied ***, according to the processing maps and microstructure analysis, it suggested that hot working of medium Mn steel should be carried out at 1050 ℃, and the strain rate of 0.05–10 s-1 resulted in significantly recrystallized microstructures in the in *** flow localization is mainly flow instability mechanism for experimental steel.

关键词： Medium-Mn steel Hot deformation behavior Constitutive equations Flow instability mechanism recrystallized microstructure

Strength-ductility synergy in a 1.4 GPa austenitic steel with a heterogeneous lamellar microstructure

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Journal of Materials Science & Technology 2022年第11期106卷 133-138页

作者： Gang Niu Hatem S.Zurob r.d.k.misra Huibin Wu Yu Zou department of Materials Science and Engineering University of TorontoTorontoONM5S 3E4Canada Collaborative Innovation Center of Steel TechnologyUniversity of Science and Technology BeijingBeijing 100083China department of Materials Science and Engineering McMaster UniversityHamiltonONL8S 4L7Canada department of Metallurgical Materials and Biomedical EngineeringUniversity of Texas at El PasoEl PasoTX 79968USA Collaborative Innovation Center of Steel Technology University of Science and Technology BeijingBeijing 100083China department of Materials Science and Engineering University of TorontoTorontoONM5S 3E4Canada

*** Advanced high-strength steels with good ductility are essen-tial to the manufacturing,structural safety,and light-weighting of load-bearing structures in many industries[1-3].Austenitic stain-less steel(ASS)exhibits high ductility due to the TrIP and/or TWIP effect that can alleviate stress concentration,prevent void nucle-ation,enhance work hardening,and postpone necking[4-6].The yield strength of conventional ASS is generally low(∼200-500 MPa),and their deformation resistance is insufficient for many load-bearing applications[6].Previous studies reported the in-creased yield strength in various austenitic steels through grain refinement,dislocation strengthening,precipitation strengthening,and heterogeneous hardening[7-14].A single strengthening mech-anism,however,is typically insufficient to obtain ultrahigh yield strength over 1 GPa in austenitic steel[12].

关键词： steel ductility austenitic

Effects of Nb and V on Microstructural Evolution,Precipitation Behavior and Tensile Properties in Hot-rolled Mo-bearing Steel

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Journal of Iron and Steel research International 2016年第6期23卷 559-565页

作者： Fu-ming LIU Jian-jun WANG Yu-jie LIU r.d.k.misra Chun-ming LIU School of Materials Science and Engineering Northeastern University key Laboratory for Anisotropy and Texture of Materials of Ministry of Education Northeastern University Laboratory for Excellence in Advanced Steel research Department of Metallurgical and Materials EngineeringUniversity of Texas at El Paso

Microstructural evolution,precipitation behavior,and tensile properties of four experimental Mo-bearing steels were studied to elucidate the effects of Nb and V on microstructural *** results indicated that the microstructure of hot-rolled steels consisted of polygonal ferrite and degenerate pearlite,and the morphology remained same after holding at 600 ℃for *** smallest grain size was obtained in Nb-V-Mo containing steel,followed by Nb-Mo and V-Mo *** was less in the hot-rolled Mo-bearing *** maximum volume fraction of precipitates was obtained in Nb-V-Mo bearing steel,and the Nb-V-Mo complex carbonitrides were highly stable at 600℃.In the Mo-bearing steel,the yield ratio was lowest at room temperature but highest at 600℃,which was attributed to the precipitation of Mo carbides and drag effect of Mo solute on dislocation movement.

关键词： rolled steels Precipitation tensile solute attributed polygonal holding ferrite dislocation

Structure-property relationships in heat-affected zone of gas-shielded arc-welded V-N microalloyed steel

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Journal of Iron and Steel research International 2018年第12期25卷 1244-1254页

作者： Jun Hu Lin-xiu du Bin Zhang Xiang-yu Qi Xiu-hua Gao r.d.k.misra The State key Laboratory of rolling and Automation Northeastern UniversityShenyang 110819LiaoningChina Laboratory for Excellence in Advanced Steel research Department of MetallurgicalMaterials and Biomedical EngineeringUniversity of Texas at El PasoEl Paso TX 79968-0521USA

The structure-property relationship in heat-affected zone (HAZ)of a low-carbon steel bearing V-N subjected to gasshielded arc welding was *** microstructural characteristics of base metal (BM),coarse-grained HAZ (CGHAZ),fine-grained HAZ,and intercritical HAZ were significantly *** effect of grain-refinement strengthening and transformation hardening on HAZ contributed to equivalent hardness of 260.8-278.5 HV in comparison with BM hardness of 272.0 ***,excellent impact toughness at -20 ℃ was obtained because of high resistance to crack propagation by high-misorientation boundaries,leading to impact fracture consisting of *** CGHAZ,free N was partly fixed by V(C,N)precipitates,such that the deterioration effect of N on toughness was considered to be nearly *** comparison with CGHAZ,weld metal contained higher fraction of acicular ferrite with fine plates,while the impact toughness was inferior because of the detrimental influence of coarse inclusions from the welding *** nanoscale V(C,N)precipitates in CGHAZ had weak effect on toughness because of small size.

关键词： V-N microalloying Heat-affected zone Acicular ferrite Hardness Toughness Gas-shielded arc welding V-N microalloyed steel

Signifcant impact of cold-rolling deformation and annealing on damping capacity of Fe-Mn-Cr alloy

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Journal of Iron and Steel research International 2020年第5期27卷 566-576页

作者： Bo Xia Xiao-ming Zhang r.d.k.misra Ming-ming Pan Yu-qian Wang State key Laboratory of rolling and Automation Northeastern UniversityShenyang 110819LiaoningChina Laboratory for Excellence in Advanced Steel research Department of MetallurgicalMaterials and Biomedical EngineeringUniversity of Texas at El PasoEl PasoTX 79668USA

The infuences of cold-rolling deformation and annealing on the damping capacity of Fe-19Mn-8Cr alloy were *** was observed that the cold-rolled Fe-19Mn-8Cr alloy with a reduction of 10%showed the relatively excellent damping capacity because of the relatively moreε-martensite and lower dislocation density,and the reduction of slopes of diferent damping curves increased along with increasing the cold-rolling ***,the subsequent annealing process can further enhance the damping *** 70%cold-rolling deformation,the austenite grain would grow up with the increase in the annealing temperature,which resulted in a signifcant change in the content and morphology ofε-martensite infuencing the damping capacity of the experimental *** damping capacity was optimum when annealed at 800°C for 30 min,displaying that the size ofε-martensite has a vital infuence on the damping capacity of the experimental *** study may enrich the fundamental knowledge about how to ameliorate the damping capacity of Fe-Mn-Cr damping steels.

关键词： damping capacity Fe-19Mn-8Cr damping alloy ε-martensite α′-martensite Cold rolling

Significant effect of as-cast microstructure on texture evolution and magnetic properties of strip cast non-oriented silicon steel

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Journal of Materials Science & Technology 2018年第12期34卷 2472-2479页

作者： Haitao Jiao Yunbo Xu Wenzheng Qiu Haijie xu r.d.k.misra Yifeng du Jianping Li Guodong Wang State key Laboratory of rolling and Automation Northeastern UniversityShenyang 110819China Laboratory for Excellence in Advanced steel research Department of MetallurgicalMaterialsand Biomedical EngineeringUniversity of Texas at El PasoTX 79968USA Liaoyang Petroleum Steel Pipe Manufacturing Company Liaoyang 111003China

In this study, two types of as-cast microstructure produced by strip casting were cold rolled and annealed to investigate the effect of initial microstructure on the textural evolution and magnetic properties of non-oriented silicon steel. The results indicated that the cold-rolled sheets of coarse-grained strip with pronounced r components exhibited stronger 入 fiber(//Nd) and weaker γ fiber(//Nd)texture as composed to the fine-grained strip with strong Goss({110}(001)) texture. After annealing, the former was dominated by η fiber(//rd) texture with a peak at {110}rientation, while the latter consisted of strong {111}(112) and relatively weak {110}(001) texture. In addition, a number of precipitates of size ～30-150 nm restricted the grain growth during annealing, resulting in recrystallization of grain size of ～46 μm in the coarse-grained specimen and ～41μm in the fine-grained ***, higher magnetic induction(～1.72 T) and lower core loss(～4.04 W/kg) were obtained in the final annealed sheets of coarse-grained strip with strong r texture.

关键词： As-cast microstructure Non-oriented silicon steel Strip casting Texture Magnetic properties