) 上海交通大学 机械与动力工程学院, 上海 200240
收稿日期:2020-11-20出版日期:2021-11-28发布日期:2021-12-03通讯作者:李大永E-mail:dyli@sjtu.edu.cn作者简介:杨 浩(1992-),男,安徽省合肥市人,博士生,从事晶体塑性与马氏体相变研究.基金资助:国家自然科学基金项目(U1860110);国家重点研发计划项目(2020YFB2010300)Crystal Plasticity Modeling of Tension Process of QP980 Steel
YANG Hao, WANG Huamiao, LI Dayong() School of Mechanical Engineering, Shanghai Jiao Tong University, Shanghai 200240, China
Received:2020-11-20Online:2021-11-28Published:2021-12-03Contact:LI Dayong E-mail:dyli@sjtu.edu.cn摘要/Abstract
摘要： 淬火配分QP980钢变形过程中存在马氏体相变,对材料的力学性能产生明显影响.通过电子背散射衍射方法表征了QP980钢变形前后的微观组织,基于马氏体相变晶体学唯象理论建立了考虑相变的弹-黏塑性自洽多晶体塑性模型,模拟了QP980钢在单向拉伸过程中的宏观流动应力和织构演化.材料初始包含铁素体(F)、马氏体和残余奥氏体(RA),各相均为轧制织构,变形后残余奥氏体含量明显减少,残余奥氏体的<111>丝织构、铁素体和马氏体的<110>丝织构在拉伸方向有明显增强.相变提高了材料的强度和加工硬化率,但对各相的织构演化影响很小.根据计算变形过程中应变和应力的分配情况,铁素体和回火马氏体对变形起主要作用,变形过程中新生马氏体的应力最大,成为断裂的潜在萌生点.
关键词: 淬火配分钢, 晶体塑性, 马氏体相变, 弹-黏塑性自洽
Abstract: The mechanical behavior of the quenching and partitioning 980 (QP980) steel is affected by martensitic transformation during deformation. The microstructure of QP980 steel before and after deformation is characterized by using the electron backscattered diffraction (EBSD) method. An elastic visco-plastic self-consistent (EVPSC) polycrystalline model considering phase transformation is established based on the phenomenological theory of martensite crystallography (PTMC). The macroscopic flow stress as well as texture evolution of QP980 steel during uniaxial tension process is reproduced by the model. The material consists of ferrite (F), martensite, and retained austenite (RA) with rolling texture in the initial state. After deformation, the content of RA decreases and the <111> fiber of the RA, the <110> fiber of the ferrite and martensite along the tensile direction are enhanced. Phase transformation enhances the strength and work hardening rate but has little effect on the texture evolution. According to the distribution of stress and strain during the calculation of deformation, ferrite and tempered martensite (TM) contribute most to the deformation, and the new martensite (NM) is the most probable nucleation sites of fracture due to its highest average stress.
Key words: quenching and partitioning (QP) steel, crystal plasticity, martensitic transformation, elastic visco-plastic self-consistent (EVPSC)
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