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Journal of Materials Science & Technology 2020年第12期47卷 1-9页

作者： Chunni Jia chengwu zheng Dianzhong Li Shenyang National Laboratory for Materials Science Institute of Metal ResearchChinese Academy of Sciences.Shenyang110016China School of Materials Science and Engineering University of Science and Technology of ChinaShenyang110016China

A mesoscopic cellular automaton model was developed to study the microstructure evolution and solute redistribution of austenization during intercritical annealing of a C-Mn steel. This model enables a depiction of three-stage kinetics of the transformation combined with the thermodynamic analysis:(1) the rapid austenite growth accompanied with pearlite degeneration until the pearlite dissolves completely;(2) the slower austenite growth into ferrite with a rate limiting factor of carbon diffusion in austenite;and(3) the slow austenite growth in control of the manganese diffusion until the final equilibrium reached for ferrite and austenite. The effect of the annealing temperature on the transformation kinetics and solute partition is also quantitatively rationalized using this model.

关键词： Austenization Intercritical annealing C-Mn steels Cellular automaton Mesoscale modeling

Ultra-Fine Heterogeneous Microstructure Enables High Strength-Ductility in a Cold-Rolled Medium Mn Steel

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Acta Metallurgica Sinica(English Letters) 2022年第10期35卷 1712-1718页

作者： Baojia Hu chengwu zheng Qinyuan zheng Peng Liu Chunni Jia Dianzhong Li Shenyang National Laboratory for Materials Science Institute of Metal ResearchChinese Academy of SciencesShenyang110016China School of Materials Science and Engineering University of Science and Technology of ChinaShenyang110016China

The objective of the present study is to develop heterogeneous microstructure in cold-rolled medium Mn steels(MMSs)annealing *** cold-rolled Fe-4.7Mn-0.15C(wt%)steel is annealed twice at different temperatures to produce an ultra-fine heterogeneous microstructure with lath-shaped and granular-shaped retained *** mechanical behavior of significant strength enhancement with negligible ductility loss can be *** high strength-ductility properties are attributed to the active transformation induced plasticity effect over a broad strain range owing to dispersive mechanical stabilities of the heterogeneous ***,the typical yield point elongation phenomenon which is commonly observed in cold-rolled MMSs can be effectively reduced by this microstructural strategy.

关键词： Cold-rolled medium Mn steel Heterogeneous structure Yield point elongation Austenite stability Mechanical properties

Synergic Evolution of Microstructure‑Texture‑Stored Energy in Rare‑Earth‑Added Interstitial‑Free Steels Undergoing Static Recrystallization

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Acta Metallurgica Sinica(English Letters) 2023年第4期36卷 661-680页

作者： Peng Liu Xiaodong Hou Chaoyun Yang Yikun Luan chengwu zheng Dianzhong Li Shenyang National Laboratory for Materials Science Institute of Metal ResearchChinese Academy of SciencesShenyang 110016China School of Materials Science and Engineering University of Science and Technology of ChinaShenyang 110016China Centre of Excellence for Advanced Materials Dongguan 523808China

Synergic evolution of microstructure-texture-stored energy in interstitial-free(IF)steels has been investigated to elaborate the effect of dissolved rare-earth(RE)elements on static *** size,texture fraction and geometrically necessary dislocation distribution of IF steel samples annealed for different times were compared,suggesting that RE elements could postpone recrystallization nucleation but accelerate grain *** visco-plastic self-consistent model was primarily adopted and verified,then used to calculate the relative activities of different slip *** was proved that the compatible deformation of IF steels was very sensitive to dissolved RE elements,in particular the{110}62 slip systems became extremely inactive,leading to anα-fibre textures rich configuration of RE-IF *** both IF steels have the same stored energy sequence of whichγ-fibre takes precedence in nucleation followed byα-fibre,the nucleation rates ofα/γ-fibres driven by the reduced stored energy slowed down in RE-IF *** nucleation-path analyses revealed that shear bands withinγ-fibre mainly sacrificed for grain nucleation of{111}orientation,whileα-fibre especially prior grain boundaries therein preferred supplying nucleation sites for{554}grains,which accounting for the competitive growth ofγ-fibre textures in RE-IF steels rather than being dominated by a single *** grain growth,the major texture of Normal-IF steels had been transferred to{554}from{111},while{554}in RE-IF steels still inherited the orientation advantage and grew up rapidly,thus inducing the grain *** this work offers a significant understanding of RE microalloying effect on static recrystallization,it will provide references for alloy design and industrial application of IF steels.

关键词： Static recrystallization IF steels RE elements Texture Grain coarsening Slip systems

Mesoscopic Analysis of Deformation Heterogeneity and Recrystallization Microstructures of a Dual-Phase Steel Using a Coupled Simulation Approach

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Acta Metallurgica Sinica(English Letters) 2021年第6期34卷 777-788页

作者： Chunni Jia Gang Shen Wenxiong Chen Baojia Hu chengwu zheng Dianzhong Li Shenyang National Laboratory for Materials Science Institute of Metal ResearchChinese Academy of SciencesShenyang 110016China School of Materials Science and Engineering University of Science and Technology of ChinaShenyang 110016China School of Mechanical Engineering Suzhou University of Science and TechnologySuzhou 215009China

Microstructure-based numerical modeling of the deformation heterogeneity and ferrite recrystallization in a cold-rolled dual-phase(DP)steel has been performed by using the crystal plasticity finite element method(CPFEM)coupled with a mesoscale cellular automaton(CA)*** microstructural response of subsequent primary recrystallization with the deformation heterogeneity in two-phase microstructures is *** simulations demonstrate that the deformation of multi-phase structures leads to highly strained shear bands formed in the soft ferrite matrix,which produces grain clusters in subsequent primary *** early impingement of recrystallization fronts among the clustered grains causes mode conversions in the recrystallization *** predictions regarding the grain size,microstructure morphology and kinetics can be made by comparison with the experimental *** influence of initial strains on the recrystallization is also obtained by the simulation approach.

关键词： Dual-phase steel Primary recrystallization Deformation heterogeneity Crystal plasticity finite element method Cellular automaton

High-Temperature Plasticity Enhanced by Multiple Secondary Phases in a High-Si Austenitic Stainless Steel

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Acta Metallurgica Sinica(English Letters) 2022年第9期35卷 1519-1530页

作者： Sihan Chen Tian Liang Guangcai Ma chengwu zheng Deli Chen Yingche Ma Kui Liu CAS Key Laboratory of Nuclear Materials and Safety Assessment Institute of Metal ResearchChinese Academy of SciencesShenyang110016China School of Materials Science and Engineering University of Science and Technology of ChinaHefei230026China Shi-Changxu Innovation Center for Advanced Materials Institute of Metal ResearchChinese Academy of SciencesShenyang110016China Shenyang National Laboratory for Materials Science Institute of Metal ResearchChinese Academy of SciencesShenyang110016China Fushun Sub Center of Technical Center Fushun Special Steel Group Co.Ltd.Fushun113001China

An austenitic stainless steel with 6 wt% Si and multiple secondary phases was produced with the aim to achieve enhanced plasticity during hot *** micro structure of the steel after fracture was characterized via electron back-scattered diffraction,transmission Kikuchi diffraction and scanning transmission electron *** the tail of the gage to the necking region,the microstructure of the material evolved from low-angle grain boundaries(LAGB s) to mixtures of LAGBs and high-angle grain boundaries(HAGBs),and fine equiaxed recrystallized *** elongation to failure in the tensile test exceeds 167%.During the hot deformation,continuous dynamic recrystallization of the austenitic matrix was promoted by the multiple secondary *** dislocations introduced by the secondary phases were rearranged and continuously transformed into *** initially coarse grains(30.5 μm) were refined into ultra-fine equiaxed grains(1 μm),which contributed significantly the enhanced plasticity during hot deformation of the *** the necking area of the sample,twins were nucleated in the stress concentration regions and accommodated the local strain by discontinuous dynamic recrystallization,which was also beneficial to improving the plasticity.

关键词： High-Si austenitic stainless steel High-temperature deformation Plasticity enhancement Dynamic recrystallization Secondary phases

Phase Characterization and Formation Behavior in 6 wt%Si High-silicon Austenitic Stainless Steel during Isothermal Aging

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Acta Metallurgica Sinica(English Letters) 2021年第5期34卷 649-656页

作者： Sihan Chen Tian Liang Yangtao Zhou Weiwei Xing chengwu zheng Yingche Ma JinMing Wu Guobin Li Kui Liu Key Laboratory of Nuclear Materials and Safety Assessment Institute of Metal ResearchChinese Academy of SciencesShenyang110016China School of Materials Science and Engineering University of Science and Technology of ChinaHefei230026China State Key Laboratory of Silicon Materials School of Materials Science and EngineeringZhejiang UniversityHangzhou310027China Zhejiang Xindeda Special Pipe Industry Co. LtdWenzhou325024China

The precipitation behavior of different phases in a high-silicon stainless steel(6 wt%Si)during aging at 600–1050℃for24 h was *** morphology,crystal structure and composition of various precipitates were detailly characterized using optical microscopy,scanning electron microscopy and transmission electron *** phases were mainly identified:χ-phase,M_6C carbides,σphase and a new type of *** aging at 600–900℃,the main precipitate was(Cr,Mo and Si)-richχ-phase which was directly precipitated fromγ***χ-phase was calibrated as bcc structure with a lattice parameter of 8.90?.The peak temperature for the precipitation ofχ-phase was 800℃,and it was dissolved when aging at temperatures above 1000℃.Theσ-phase was observed only at 700℃and grew next toχ-*** 700℃,a new fcc-phase was found to be precipitated along withχ-phase,with a space group of Fd3c and a lattice parameter of 12.56?.The M_6C carbides started to be precipitated at 700℃in the vicinity ofχ-*** its amount basically increased with the increasing of *** orientation relationship between M_6C/γwas found:[100]c//[100]γ,(001)c//(001)γ,i.e.,the cube-on-cube relationship.

关键词： High-silicon austenitic stainless steel Precipitates χ-Phase Precipitation behavior

Achieving strength-ductility synergy in cold spray additively manufactured Al/B4C composites through a hybrid post-deposition treatment

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Journal of Materials Science & Technology 2019年第6期35卷 1053-1063页

作者： Naeem ul Haq Tariq Lawrence Gyansah Xiang Qiu Chunnijia Hasan Bin Awais chengwu zheng Hao Du Jiqiang Wang Tianying Xiong Institute of Metal Research Chinese Academy of Sciences Shenyang 110016 China University of Chinese Academy of Sciences Beijing 100049 China Department of Metallurgy and Materials Engineering Pakistan Institute of Engineering and Applied Sciences Nilore Islamabad Pakistan School of Materials Science and Engineering University of Science and Technology of China Shenyang 710016 China

Cold spray additive manufacturing(CSAM) provides a potential solid state manufacturing route to fabricate variety of aluminum matrix composites(AMCs) with reduced possibility of undesired chemical reactions and residual thermal stresses. This study presents a hybrid(i.e. hot compression + hot rolling)post-deposition treatment to reinvigorate the mechanical properties of cold spray additively manufactured Al/B4 C composites. The as-deposited samples were initially subjected to 30% thickness reduction via hot compression treatment at 500°C followed by a hot rolling treatment with 40% thickness reduction in 2 passes. Electron backscatter diffraction(EBSD) and high resolution transmission electron microscopy(HRTEM) results revealed that after hybrid post-deposition treatment(involving 70%accumulative thickness reduction), the aluminum grains in the matrix were extensively refined due to simultaneous operation of continuous dynamic recrystallization(CDRX) and geometric dynamic recrystallization(GDRX). Furthermore, interfacial defects were remarkably reduced while the nature of Al/Al and Al/B4C interfacial bonding was changed from sheer mechanical interlocking to metallurgical bonding which facilitated efficient transference of applied load to uniformly dispersed bimodal B4C particles. As a result, ultimate tensile strength(UTS) and elongation(EL) of the as-deposited sample were simultaneously improved from 37 to 185 MPa and 0.3% to 6.2%, respectively.

关键词： Cold spray additive manufacturing Post-deposition treatments Al/B4C composites Dynamic recrystallization Mechanical properties

Mechanical Properties and Temper Resistance of Deformation Induced Ferrite in a Low Carbon Steel

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Journal of Materials Science & Technology 2010年第12期26卷 1107-1113页

作者： Luhan Hao,Namin Xiao,chengwu zheng and Dianzhong Li Shenyang National Laboratory for Materials Science,Institute of Metal Research,Chinese Academy of Sciences,Shenyang 110016,China [a] Shenyang National Laboratory for Materials Science Institute of Metal Research Chinese Academy of Sciences Shenyang 110016 China

The microstructures and mechanical properties of deformation induced ferrite （DIF） in the low carbon steel Q235 under different deformation temperatures have been investigated systematically. Through deformation induced ferrite transformation （DIFT）, ferrite grain can be refined to 3 μm and accounts for above 85% of the overall fraction. Yield strength of DIF （〉500 MPa） is increased by up to 100% compared with the conventional low carbon steel. Comparison of microstructure and mechanical properties in the Q235 steel with DIF and tempered DIF microstructure illustrates that the strengthening mechanism of DIF microstructure is the combination of grain boundary strengthening and carbon supersaturated strengthening. Electron back-scattered diffraction （EBSD） analysis and high magnification scanning electron microscopy （SEM） observation denote that high-angle grain boundary among ultrafine ferrite grain and the transformation product of retain austenite membrane along ferrite boundaries are responsible for the stability of ferrite grain size during tempering process. Transmission electron microscopy （TEM） analysis demonstrates that the transformation product of retained austenite membrane between ferrite grain boundaries is cementite.

关键词： Low carbon steel Deformation Mechanical properties Temper induced ferrite transformation Grain size resistance

相场法模拟Fe-C合金中奥氏体-铁素体等温相变过程

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金属学报 2016年第11期52卷 1449-1458页

作者：张军郑成武李殿中中国科学技术大学化学与材料科学学院合肥230026 中国科学院金属研究所沈阳材料科学国家(联合)实验室沈阳110016

运用相场法研究了Fe-C合金在临界区等温过程中发生的奥氏体-铁素体相变过程.通过分析铁素体生长过程中C的扩散行为,发现奥氏体-铁素体相变表现为混合控制生长的特征,奥氏体/铁素体相界面处于非平衡状态.进一步研究了不同等温温度(1010,1... 详细信息

运用相场法研究了Fe-C合金在临界区等温过程中发生的奥氏体-铁素体相变过程.通过分析铁素体生长过程中C的扩散行为,发现奥氏体-铁素体相变表现为混合控制生长的特征,奥氏体/铁素体相界面处于非平衡状态.进一步研究了不同等温温度(1010,1048和1087 K)下奥氏体-铁素体相变的微观组织和C浓度场的演化情况.结果表明,随着等温温度的降低,铁素体形核率增加,铁素体相变平衡体积分数增加,但奥氏体内部C浓度分布的不均匀程度加剧,1010 K等温时的微观组织呈现为不规则细小铁素体晶粒围绕分散分布的残余奥氏体的两相结构.随着等温温度的降低,奥氏体-铁素体相变过程表现出由扩散控制生长模式向界面控制生长模式转化的趋势.

关键词：相场法奥氏体铁素体 C浓度场混合控制相变模式

稀土元素对低碳钢中奥氏体-铁素体相变动力学的影响

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材料研究学报 2023年第7期37卷 495-501页

作者：郭飞郑成武王培李殿中中国科学院金属研究所沈阳材料科学国家研究中心沈阳110016 中国科学技术大学材料科学与工程学院沈阳110016

使用热膨胀仪等手段研究了稀土对Fe-C和Fe-C-Si-Mn低碳钢连续冷却过程奥氏体-铁素体相变温度和等温过程相变动力学的影响。结果表明,添加微量的RE元素可显著降低连续冷却过程中先共析铁素体相变的开始点温度。同时,添加微量稀土还能改... 详细信息

使用热膨胀仪等手段研究了稀土对Fe-C和Fe-C-Si-Mn低碳钢连续冷却过程奥氏体-铁素体相变温度和等温过程相变动力学的影响。结果表明,添加微量的RE元素可显著降低连续冷却过程中先共析铁素体相变的开始点温度。同时,添加微量稀土还能改变等温过程中的铁素体相变动力学:RE元素通过抑制碳扩散减缓了Fe-C-(RE)合金整个相变过程的相变速率;而对于Fe-C-Si-Mn合金,RE通过抑制C元素扩散和改变晶界能的双重作用,使其相变孕育期延长和相变初始阶段速率降低,但是提高了相变中后期的速率。

关键词：金属材料相图与相变低碳钢奥氏体-铁素体相变动力学稀土元素