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Enhancing the Hydrogen Embrittlement Resistance of Medium Mn Steels by Designing Metastable Austenite with a Compositional Core-shell Structure

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Acta Metallurgica Sinica(English Letters) 2023年第7期36卷 1059-1077页

作者： Jun Zhang binhan sun Zhigang Yang Chi Zhang Hao Chen Key Laboratory for Advanced Materials of Ministry of Education School of Materials Science and EngineeringTsinghua UniversityBeijing 100084China Key Laboratory of Pressure Systems and Safety Ministryof EducationSchool of Mechanical and Power EngineeringEast China University of Science and TechnologyShanghai 200237China

Deformation-induced martensite transformation from metastable retained austenite is one of the most efficient strain-hardening mechanisms contributing to the enhancement of strength-ductility synergy in advanced high-strength ***,the hard transformation product(often-martensite)and the H redistribution associated with phase transformation essentially decrease materials’resistance to hydrogen *** solve this fundamental conflict,we introduce a new microstructure architecting strategy based on an accurately design of core–shell compositional distribution inside the austenite *** employed this approach in a typical medium Mn steel(8 wt.%Mn)with an ultrafine grained austenite-ferrite *** produced a high Mn content(15–16 wt.%)in the austenite shell region and a low Mn content(~12 wt.%)in the core region,through a thermodynamics-guided two-step austenite reversion *** room-temperature deformation,the austenite core transforms continuously starting from a low strain,providing a high and persistent strain-hardening *** transformation of Mn-rich austenite shell,on the other hand,occurs only at the latest regime of the deformation,thus effectively inhibiting the nucleation of H-induced cracks at ferrite/deformation-induced martensite interfaces as well as suppressing their growth and *** step-wise transformation,tailored directly targeted to protect the hydrogen-sensitive microstructure defects(interfaces),results in a significantly enhanced hydrogen embrittlement resistance without sacrificing the mechanical performance in hydrogen-free *** design of compositional core–shell structure is expected to be applicable to,at least,other multiphase advanced high-strength steels containing metastable austenite.

关键词： Medium Mn steels Hydrogen embrittlement Core-shell austenite Chemical heterogeneity Deformationinduced martensite transformation

Current Challenges and Opportunities Toward Understanding Hydrogen Embrittlement Mechanisms in Advanced High-Strength Steels: A Review

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Acta Metallurgica Sinica(English Letters) 2021年第6期34卷 741-754页

作者： binhan sun Dong Wang Xu Lu Di Wan Dirk Ponge Xiancheng Zhang Max-Planck-Institut flir Eisenforschung GmbH Max-Planck-StraBe 140237 DlisseldorfGermany Department of Mechanical and Industrial Engineering Norwegian University of Science and TechnologyRichard Birkelands vei 2B7491 TrondheimNorway Key Laboratory of Pressure Systems and Safety Ministry of EducationSchool of Mechanical and Power EngineeringEast China University of Science and TechnologyShanghai 200237China

Hydrogen embrittlement(HE)is one of the most dangerous yet most elusive embrittlement problems in metallic *** high-strength steels(AHSS)are particularly prone to HE,as evidenced by the serious degradation of their load-bearing capacity with the presence of typically only a few parts-per-million *** strongly impedes their further development and application and could set an abrupt halt for the weight reduction strategies pursued globally in the automotive *** is thus important to understand the HE mechanisms in this material class,in order to develop effective H-resistant ***,we review the related research in this field,with the purpose to highlight the recent progress,and more importantly,the current challenges toward understanding the fundamental HE mechanisms in modern *** review starts with a brief introduction of current HE models,followed by an overview of the state-of-the-art micromechanical testing techniques dedicated for HE ***,the reported HE phenomena in different types of AHSS are critically *** are particularly placed on two representative multiphase steels,i.e.,ferrite–martensite dual-phase steels and ferrite–austenite medium-Mn steels,with the aim to highlight the multiple dimensions of complexity of HE mechanisms in complex *** on this,open scientific questions and the critical challenges in this field are discussed to guide future research efforts.

关键词： Hydrogen embrittlement Advanced high-strength steels(AHSS) Damage mechanisms Multiphase steels

Evaluation of hydrogen effect on the fatigue crack growth behavior of medium-Mn steels via in-situ hydrogen plasma charging in an environmental scanning electron microscope

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Journal of Materials Science & Technology 2021年第26期85卷 30-43页

作者： Di Wan Yan Ma binhan sun Seyed Mohammad Javad Razavi Dong Wang Xu Lu Wenwen Song Department of Mechanical and Industrial Engineering Norwegian University of Science and TechnologyRichard Birkelands vei 2B7491TrondheimNorway Steel Institute(IEHK) RWTH Aachen UniversityIntzestraße 152072AachenGermany Max-Planck-Institut für Eisenforschung GmbH Max-Planck-Straße 140237DüsseldorfGermany

Fatigue crack growth(FCG)tests were conducted on a medium-Mn steel annealed at two intercritical annealing temperatures,resulting in different austenite(γ)to fe rrite(α)phase fractions and differentγ(meta-)*** in-situ hydrogen plasma charging was combined with in-situ cyclic loading in an environmental scanning electron microscope(ESEM).The in-situ hydrogen plasma cha rging increased the fatigue crack growth rate(FCGR)by up to two times in comparison with the reference tests in *** investigations showed a brittle-like crack growth or boundary cracking manner in the hydrogen environment while a ductile transgranular manner in *** both materials,the plastic deformation zone showed a reduced size along the hydrogen-influenced fracture path in comparison with that in *** difference in the hydrogen-assisted FCG of the medium-Mn steel with different microstructures was explained in terms of phase fraction,phase stability,yielding strength and hydrogen *** refined study can help to understand the FCG mechanism without or with hydrogen under in-situ hydrogen charging conditions and can provide some insights from the applications point of view.

关键词： Hydrogen embrittlement Fatigue crack growth(FCG) Electron channeling contrast imaging(ECCI) Medium-Mn steel Hydrogen plasma

Precipitation and heterogeneous strengthened CoCrNi-based medium entropy alloy with excellent strength-ductility combination from room to cryogenic temperatures

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Science China(Technological Sciences) 2022年第8期65卷 1780-1797页

作者： XIE Yu ZHAO PengCheng TONG YongGang TAN JianPing sun binhan CUI Yan WANG RunZi ZHANG XianCheng TU ShanTung Key Laboratory of Pressure Systems and Safety Ministry of EducationSchool of Mechanical and Power EngineeringEast China University of Science and TechnologyShanghai 200237China College of Automobile and Mechanical Engineering Changsha University of Science and TechnologyChangsha 410114China Key Laboratory for Advanced Materials and Feringa Nobel Prize Scientist Joint Research Center Institute of Fine ChemicalsSchool of Chemistry&Molecular EngineeringEast China University of Science and TechnologyShanghai 200237China

The improved understandings of the mechanical properties as well as deformation mechanisms at cryogenic temperatures are the prerequisite for realizing the application of any new engineering materials to cryogenic ***,a(CoCrNi)_(94)Al_(3)Ti_(3) medium entropy alloy(MEA)with nanoscale L12 coherent precipitates and heterogeneous grain structures was prepared by codoping Al and Ti elements with subsequent cold rolling and heat treatment *** mechanical properties were evaluated at the temperature range of 293–113 *** ultimate strength of the MEA increases almost linearly from 1326 to 1695 MPa as the temperature decreases from 293 to 113 K,while the total elongation remains approximately constant of~35%.The underlying deformation and strengthening mechanisms were investigated using various characterization *** to the effect of co-doped Al/Ti on channel width of the matrix and the increasing critical twinning stress induced by heterogeneous ultrafine grain size,the formation of deformation twins is inhibited at all ***,only a slight increase of the deformation twins and stacking faults in the deformed specimens with a decreasing temperature,which leads to the relative temperature-independence of the *** dislocation cutting mechanism of L1_(2) coherent precipitates and the heterodeformation induced(HDI)hardening both significantly contribute to the strain hardening so that an excellent combination of strength and ductility is ***,the evolution of lattice friction stress with deformation temperature is determined by quantitative analysis,indicating an approximately linear relationship between the lattice friction and *** present work provides new insights into the strategy of achieving outstanding strength-ductility synergy of the MEA under the wide temperature range by coupling heterogeneous ultrafine-grained structure and coherent precipitation strategy.

关键词： medium entropy alloy cryogenic temperature heterogeneous structure precipitation strengthening twinning

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Effects of post annealing on the microstructure,precipitation behavior,and mechanical property of a(CoCrNi)_(94)Al_(3)Ti_(3)medium-entropy alloy fabricated by laser powder bed fusion

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Journal of Materials Science & Technology 2023年第4期135卷 142-155页

作者： Zhuang Li Pengcheng Zhao Tiwen Lu Kai Feng Yonggang Tong binhan sun Ning Yao Yu Xie Bolun Han Xiancheng Zhang Shantung Tu Key Laboratory of Pressure Systems and Safety Ministry of EducationSchool of Mechanical and Power EngineeringEast China University of Science and TechnologyShanghai 200237China Shanghai Key Laboratory of Materials Laser Processing and Modification School of Materials Science and EngineeringShanghai Jiao Tong UniversityShanghai 200240China College of Automobile and Mechanical Engineering Changsha University of Science and TechnologyChangsha 410114China

The additive manufacturing of multi-principal element alloys has remarkable potential for industrial *** this study,a(CoCrNi)_(94)Al_(3)Ti_(3)medium-entropy alloy(MEA)with adequate strength-ductility synergy was prepared via laser powder bed *** microstructural evolution,mechanical property,and deformation mechanisms of the MEA were investigated after post annealing for a short period(0.5 h)at a temperature range of 773-1373 K using various microstructural characterization techniques and quantitative *** static recrystallization temperature of the(CoCrNi)_(94)Al_(3)Ti_(3)MEA ranged from 973 to 1073 *** average grain size first decreased and then increased,while the dislocation den-sity persistently decreased and texture gradually weakened with increasing annealing ***-richσ-phase precipitates formed after 1073 K and then gradually dissolved at 1373 K,while Ni,Al,and Ti elements were aggregated to form a small amount of fine L1_(2)coherent precipitates with an aver-age diameter of approximately 70 nm at 1373 *** evolution of the dislocation density,grain size,and precipitates significantly influenced the propensity of deformation twins and stacking faults,which consequently affected the strain hardening behavior and mechanical *** quantitative calcu-lation of strengthening mechanisms showed that dislocation strengthening played a dominant role at annealing temperatures below 1073 K,and it significantly weakened at 1373 *** and grain boundary strengthening both markedly increased owing to the formation of precipitation particles and recrystallization-induced grain refinement after annealing at 1073 K.

关键词： Medium-entropy alloy Additive manufacturing Heat treatment Strengthening mechanism Microstructural evolution

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跨越信息门槛有助于测土配方施肥技术推广吗

农业技术经济 2024年第11期 34-50页

作者：孙彬涵罗小锋华中农业大学经济管理学院武汉430070

本文基于信息不完全视角,分析技术信息储备影响农户采纳行为的逻辑机理,并利用鄂、赣、浙3省763户稻农的微观调查数据,通过内生转换Probit模型实证检验跨越信息门槛对农户测土配方施肥技术采纳行为的影响效应。在此基础上,进一步探索助... 详细信息

本文基于信息不完全视角,分析技术信息储备影响农户采纳行为的逻辑机理,并利用鄂、赣、浙3省763户稻农的微观调查数据,通过内生转换Probit模型实证检验跨越信息门槛对农户测土配方施肥技术采纳行为的影响效应。在此基础上,进一步探索助力农户跨越信息门槛的有效途径。研究发现:第一,农户对测土配方施肥技术了解不足,采纳率不高;第二,农户掌握技术信息的程度对其采纳行为的正向影响存在门槛效应,跨越信息门槛能够带动农户技术采纳的可能性提升0.4285;第三,农户的信息门槛因种植规模不同存在差异,门槛值随种植规模的扩大呈“高—低—高”的“U”形分布,即适度规模经营有助于农户跨越信息门槛,提高技术采纳率;第四,掌握农资供应和技术指导相关信息对小规模农户的技术采纳行为起到关键作用,大规模农户则更注重技术信息储备的全面性。

关键词：测土配方施肥技术技术信息技术采纳信息门槛种植规模

测土配方施肥技术环节认知对农户采纳行为的影响——基于水平和结构的双重视角

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干旱区资源与环境 2021年第8期35卷 51-57页

作者：孙彬涵罗小锋黄炎忠华中农业大学经济管理学院武汉430070 华中农业大学农村可持续发展研究中心武汉430070

测土配方施肥技术的推广应用是实现化肥减量增效的重要方式。本文基于认知行为理论,利用鄂、赣、浙三省农户微观调研数据,测度农户测土配方施肥各环节技术认知,并从认知水平和结构视角,探讨农户技术环节认知对其采纳行为的影响。研究发... 详细信息

测土配方施肥技术的推广应用是实现化肥减量增效的重要方式。本文基于认知行为理论,利用鄂、赣、浙三省农户微观调研数据,测度农户测土配方施肥各环节技术认知,并从认知水平和结构视角,探讨农户技术环节认知对其采纳行为的影响。研究发现:农户测土配方施肥技术总认知水平整体偏低,各环节认知水平的高低顺序为配肥环节>供应环节>配方环节>施肥指导环节>测土环节。农户测土配方施肥技术不同环节认知对其采纳行为具有影响差异。测土、配方、供应、施肥指导环节认知水平显著促进测土配方施肥技术采纳,配肥环节认知水平则存在显著负向影响。从结构上来看,施肥指导认知占优型农户采纳该技术的可能性最大。建议相关部门在加强生产监管的同时规范市场秩序,并适度增加对技术原理的宣传与介绍,助力我国农业高质量发展。

关键词：测土配方施肥技术技术环节农户认知化肥减量

农技推广服务数字化对粮食绿色生产率的影响——兼论老龄化与数字鸿沟的作用

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干旱区资源与环境 2024年第12期38卷 55-68页

作者：赵雯歆罗小锋唐林孙彬涵华中农业大学经济管理学院武汉430070 武汉工程大学法商学院武汉430205 湖北农村发展研究中心武汉430070

在数字经济与可持续战略统筹发展的进程中,农技推广服务数字化是提升粮食绿色生产率的重要渠道。文中基于湖北省1107户粮农调查数据,采用DEA-SBM模型测算农户粮食绿色生产率,并借助Tobit模型探究在老龄化与数字鸿沟的双重视角下,农技推... 详细信息

在数字经济与可持续战略统筹发展的进程中,农技推广服务数字化是提升粮食绿色生产率的重要渠道。文中基于湖北省1107户粮农调查数据,采用DEA-SBM模型测算农户粮食绿色生产率,并借助Tobit模型探究在老龄化与数字鸿沟的双重视角下,农技推广服务数字化对粮食绿色生产率的异质性影响及作用机制。研究结果显示:1)数字农技推广服务及其采纳频率对农户粮食绿色生产率存在显著提升作用。2)数字农技推广服务通过促进农户对农业绿色生产技术的采纳,进而提升粮食绿色生产率。3)老龄化程度对粮食绿色生产率存在负向影响,且老龄化程度会抑制数字农技推广服务对粮食绿色生产率的促进作用。4)数字鸿沟的扩张会阻碍粮食绿色生产率的提升,且数字鸿沟会抑制数字农技推广服务对粮食绿色生产率的促进作用。5)相较于传统农技推广服务而言,数字农技推广服务的农户采用效果更好。因此,应加大数字农技推广力度,分散老龄化加深的压力,增加农村教育建设与农业技术培训投资,增强农户信息化应用能力,完善农村互联网基础设施建设,推进粮食绿色生产高质量发展。

关键词：数字农技推广服务粮食绿色生产率老龄化数字鸿沟绿色生产技术

缘何有机肥在经济作物中推广更顺利?——基于市场环境的讨论

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中国农业大学学报 2024年第6期29卷 249-262页

作者：孙彬涵罗小锋唐林桑贤策华中农业大学经济管理学院武汉430070 华中农业大学湖北农村发展研究中心武汉430070 武汉工程大学法商学院武汉430205

为探究有机肥替代技术在经济作物和粮食作物种植中应用存在差距的原因,通过构建“作物类型-市场环境感知-有机肥施用行为”的逻辑框架,基于豫鄂两省987个农户的微观调查数据,利用Probit和Tobit模型,分析农户主营作物类型对有机肥施用行... 详细信息

为探究有机肥替代技术在经济作物和粮食作物种植中应用存在差距的原因,通过构建“作物类型-市场环境感知-有机肥施用行为”的逻辑框架,基于豫鄂两省987个农户的微观调查数据,利用Probit和Tobit模型,分析农户主营作物类型对有机肥施用行为的影响效应,并使用层级回归法检验其作用机制。结果表明:1)相较于种粮户,有机肥替代技术在经济作物种植户中的采纳率及采纳程度明显更高;2)农户主营作物类型通过影响价格感知作用于其有机肥施用行为,在控制作物特性差异后该效应仍然存在,而销量感知的中介作用不显著;3)作物类型通过价格感知影响农户有机肥施用行为的作用路径,仅存在于以市场收益为导向的利润型农户中,对自给型农户有机肥施用行为的影响有限。因此,应该进一步规范粮食农产品市场秩序,保障优质优价机制的有效运行,并强化技术推广举措的针对性,促进有机肥替代技术入户,助力农业绿色发展。

关键词：有机肥经济作物粮食作物市场环境感知