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Transformation Behavior of Precipitates in a W-alloyed 10 wt pct Cr Steel for Ultra-supercritical Power Plants

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Journal of materials science & Technology 2010年第9期26卷 817-822页

作者： xiaoqiang Hu,namin xiao,Xinghong Luo 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

Thermodynamic calculation,thermal analysis,and identification and observation of precipitates have been carried out on a W-alloyed 10 wt pct Cr steel by means of ThermoCalc program,differential thermal analysis（DTA）,X-ray diffraction（XRD） and transmission electron microscopy（TEM） with an energy dispersive Xray spectrometer,*** critical phase transformation points were determined by combining experimental results with *** individually stable phases of Nb（C,N） and VN,instead of one single phase MX（X：C,N）,M23C6 or Laves phases,were predicted in the calculated equilibrium phase *** unstable elongated M7C3 with relatively higher Cr was detected unexpectedly in the normalized and tempered *** kinds of spherical Nb（C,N） with different size were recognized as the primary and the secondary precipitates of Nb（C,N） which contain different V *** was observed that one kind of complex precipitate in a special V-wing shape was resulted from two plate-like VN adhering to coarse primary spherical Nb（C,N）.

关键词： Heat resistant steel Phase transformation Microstructure MX(X:C N) precipitate

Exploring the ultrahigh rolling contact fatigue life of M50 bearing steel by adjusting the cryogenic sequence

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Journal of materials science & Technology 2024年第2期169卷 243-250页

作者： Xin Cai xiaoqiang Hu Xingyu Lu Hongwei liu Yanfei Cao dianzhong li shenyang national laboratory for materials science Institute of Metal ResearchChinese Academy of SciencesShenyang 110016China

The influence of different cryogenic sequences on the rolling contact fatigue(RCF)life of M50-bearing steel has been *** results show that direct cryogenic treatment after quenching can effectively improve RCF *** L_(10)life is strikingly 5 times longer than that with cryogenic treatment after *** is caused by the distinct lattice construction of martensite and the transformation of retained *** secondary nanocarbides and fine twins are formed via cryogenic treatment before tem-pering compared with cryogenic treatment after *** improvement in the RCF life of the steel is attributed to the joint effects of the secondary nanocarbides and twin boundaries with a width of 5-13 nm,which delays significantly crack initiation and *** study highlights a common method to improve the service life of high-carbon and high-alloy steels by adjusting the cryogenic se-quence.

关键词： M50 steel Cryogenic treatment Rolling contact fatigue life Carbide Twin

Cerium refinement of grains and primary carbides during solidification of Cr_(4)Mo_(4)V bearing steel

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Journal of Rare Earths 2024年第4期42卷 783-792页

作者： Weifeng liu Jianqiang Wang Mingyue Sun Bin Xu Jiahao Yao Qunbo Fan dianzhong li Chongqing Innovation Center Beijing Institute of TechnologyChongqing401135China shenyang national laboratory for materials science Institute of Metal ResearchChinese Academy of SciencesShenyang110016China

The effect of cerium(Ce)on the solidification microstructure of Cr_(4)Mo_(4)V bearing steel was investigated via a combined experimental and theoretical *** a trace amount(0.056 wt%)of Ce addition,the coarse columnar grains in as-cast microstructure transform into equiaxed ones,and the average diameter is reduced from 56 to 27μ*** network-like and bulky primary MC and M2C carbides at the interdendritic regions become disconnected and refined,and their volume percentage decreases from4.15 vol%to 2.1 vol%.Ce-inclusions acting as heterogeneous nucleation agents of prior-austenite grains and Ce atoms segregating at grain boundaries,both contribute to the refinement of *** calculations reveal that primary carbides are precipitated afterγ-austenite forms near the end of the solidification *** modification of primary carbides in size and amount is mainly attributed to the isolated remaining melt separated by refinedγ-austenite grains in which the nucleation of carbides is promoted,while the growth is restrained owing to the less segregation of alloying elements.

关键词： Cr_(4)Mo_(4)V bearing steel Rare Earths Grains Primary carbides Refinement

Characterizations of Dynamic Strain-induced Transformation in Low Carbon Steel

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Journal of materials science & Technology 2012年第12期28卷 1095-1101页

作者： luhan hao Mingyue Sun namin xiao dianzhong li shenyang national laboratory for materials science Institute of Metal Research Chinese Academy of Sciences ShenYang 110016 China national Engineering research Center for Equipment and Technology of Cold Strip Rolling Yanshan University Qinhangdao 066004 China

Dynamic strain-induced transformation of the low carbon steel Q（235） at 770℃ and 850℃ leads to fine ferrite grains. The microstructure characterization and mechanism of the fine ferrite grain were studied by scanning electron microscopy （SEM）, transmission electron microscopy （TEM） and electron backscattered diffraction （EBSD） technique. The results show that strain-induced microstructure is the mixed microstructure of ferrite and pearlite, with cementite randomly distributed on ferrite grain boundaries and the grains interiors. EBSD images of grain boundaries demonstrate that high angle grain boundaries （HAGBs） are dominant in both of the deformation induced microstructures occurring below and above A（e3） , with only a few low angle grain boundaries （LAGBs） existing in the grain interiors. It implies that the dynamic strain-induced transformation （DSIT） happens above and below A（e3） temperature and has the same phase transition mechanisms. The refinement of ferrite is the cooperative effect of DSIT and continuous dynamic recrystallization （CDRX） of ferrite. Besides, DSIT is deemed as an incomplete carbon diffusion phase transition through the analysis of microstructure and the previous simulated results. The strengths of the Q（235） steel with refined ferrite and pearlite structure get doubled than the initial state without treated by DSIT and the residual stress in the refined structure is partly responsible for the ductility loss.

关键词： Dynamic strain-induced transformation Grain refinement Grain boundary misorientation Low carbon steel

GCr15钢滚动轴承疲劳剥落失效过程中一种针状相的形成

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金属学报 2024年第4期60卷 425-433页

作者：程胜孙阳赵文辉栾义坤郑成武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 沈阳工业大学机械工程学院沈阳110870

在发生表面剥落的GCr15钢滚动轴承的表面裂纹附近发现了一种针状相,利用SEM、透射Kikuchi衍射(TKD)和TEM等表征手段研究了这种针状相的微观特征,分析了这种针状相的形成机理及其与表面裂纹的相互作用。结果表明,在GCr15钢滚动轴承表面... 详细信息

在发生表面剥落的GCr15钢滚动轴承的表面裂纹附近发现了一种针状相,利用SEM、透射Kikuchi衍射(TKD)和TEM等表征手段研究了这种针状相的微观特征,分析了这种针状相的形成机理及其与表面裂纹的相互作用。结果表明,在GCr15钢滚动轴承表面诱发的裂纹附近所形成的针状相是一种特殊的马氏体退化组织。这种针状相是因局部应力作用而形成的细长条状组织,其三维形貌为薄板状,内部存在微观孔洞和等轴状纳米晶。在滚动接触疲劳过程中,表面裂纹会优先沿针状相的微观孔洞扩展,使针状相的形成与表面裂纹的扩展相互促进,加速了轴承表面疲劳剥落的发生。

关键词： GCr15钢滚动接触疲劳表面裂纹针状相

冷轧中锰钢的再结晶调控及其对力学性能的影响

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金属学报 2024年第2期60卷 189-200页

作者：胡宝佳郑沁园路轶贾春妮梁田郑成武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 中国科学院金属研究所中国科学院核用材料与安全评价重点实验室沈阳110016

为探究铁素体再结晶对冷轧中锰钢微观组织与力学性能的影响规律,以0.15C-5Mn(质量分数,%)冷轧中锰钢为研究对象,采用两步临界区退火的热处理方法,利用SEM、TEM和EBSD等表征手段和力学性能测试方法,研究了铁素体再结晶调控对冷轧中锰钢... 详细信息

为探究铁素体再结晶对冷轧中锰钢微观组织与力学性能的影响规律,以0.15C-5Mn(质量分数,%)冷轧中锰钢为研究对象,采用两步临界区退火的热处理方法,利用SEM、TEM和EBSD等表征手段和力学性能测试方法,研究了铁素体再结晶调控对冷轧中锰钢多样化残余奥氏体形成及其力学性能的影响。结果表明,通过在不同温度预先调控冷轧中锰钢中的铁素体再结晶,可获得由不同比例的等轴状再结晶铁素体和马氏体组成的双相细晶组织。经常规退火处理后,在终态组织中形成了不同体积分数的超细晶再结晶铁素体和呈等轴状/板条状形貌的多样化细晶残余奥氏体,使中锰钢在拉伸变形过程中表现出多样化的TRIP效应,在提升冷轧中锰钢强塑性能的同时,其Lüders变形也获得改善。

关键词：冷轧中锰钢铁素体再结晶残余奥氏体 TRIP效应力学性能

Influence of Component Size on the Corrosion Behavior of Ti6Al4V Alloy Fabricated by Electron Beam Powder Bed Fusion

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Acta metallurgica Sinica(English Letters) 2024年第1期37卷 159-168页

作者： Hongyu zheng Xin Gai Yun Bai Wentao Hou Shujun li Yulin hao R.D.K.Misra Rui Yang institute of metal research Chinese Academy of SciencesShenyang110016China School of materials science and Engineering University of Science and Technology of ChinaShenyang110016China Nuclear Power institute of china Chengdu610213China Department of metallurgical Materialsand Biomedical EngineeringThe University of Texas at El Paso500WUniversity AvenueEl PasoTX79968USA

The electrochemical behavior of Ti-6Al-4V with 1 mm and 16 mm thickness prepared by electron beam powder bed fusion(EB-PBF)was investigated in phosphate buffered *** results showed that EB-PBF Ti-6Al-4V with a larger component size was more resistant to corrosion compared to the smaller component,because of less acicularαʹphase content and moreβphase *** a non-equilibrium phase in the“high-energy state”,αʹphase has a greater susceptibility to corrode and reduces the corrosion resistance of the material,whileβphase improves corrosion resistance of titanium *** results show that the phase composition has a more significant effect on the corrosion performance than the grain size.

关键词： Electron beam powder bed fusion Ti6Al4V alloy Corrosion resistance Component size Polarisation

Cellular automaton modeling of austenite formation from ferrite plus pearlite microstructures during intercritical annealing of a C-Mn steel

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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

依托大科学装置开展建制化材料研究——大科学装置材料研究专刊前言

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金属学报 2024年第8期60卷 I0001-I0002页

作者：李殿中李昺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

随着研究的深入,人们认识到材料变得越来越复杂化。在空间维度上,基于平移对称性的长程有序晶体结构往往并不能有效、准确地描述材料的原子结构。比如多组元合金中,多种邻近元素的原子无序占据高对称性的晶格格点位置,化学起伏造成的电... 详细信息

随着研究的深入,人们认识到材料变得越来越复杂化。在空间维度上,基于平移对称性的长程有序晶体结构往往并不能有效、准确地描述材料的原子结构。比如多组元合金中,多种邻近元素的原子无序占据高对称性的晶格格点位置,化学起伏造成的电子浓度涨落以及原子适配造成的局域应变涨落使得材料的实际结构严重偏离高对称性的平均结构。而在介观尺度上,不同于均匀结构的传统材料,具有梯度结构、核壳结构、多级结构等特殊结构的异构材料先后被报道。在时间维度上,材料准静态结构和性能往往不能真实地反映材料的本来面貌,而这必须诉诸材料的瞬态结构和性质。自然地,按照结构决定性能的朴素观点,材料结构的时空不均匀性直接导致了性能表达的不确定性。

关键词：大科学装置长程有序电子浓度梯度结构介观尺度建制化时间维度原子结构