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DP1180双相钢在高应变速率变形条件下应变硬化行为及机制 被引量:22

BEHAVIOUR AND MECHANISM OF STRAIN HARDENING FOR DUAL PHASE STEEL DP1180 UNDER HIGH STRAIN RATE DEFORMATION
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摘要 利用电子万能试验机和分离式Hopkinson拉杆装置对DP1180冷轧双相钢分别进行应变速率为0.001 s^(-1)和500,1750 s^(-1)的准静态和动态拉伸实验,根据修正的Swift真应力-应变模型对实验数据进行了非线性拟合,并用修正的Crussard-Jaoul分析法计算出修正的Swift模型的应变硬化指数.结果表明:在准静态和动态拉伸下,都存在两阶段应变硬化特性,第一阶段随应变速率的增加应变硬化能力增强;第二阶段随应变速率的增加应变硬化能力减弱;转折应变随应变速率的增加从3.12%减小到1.28%.在高应变速率下,马氏体附近的铁索体由于受到变形协调性的限制,形成位错结构胞块,其尺寸可达约90 nm,而且几何必需边界(GNB)的存在使得DP1180双相钢在高应变速率下变形过程中不至于瞬间破坏;在应变速率为1750 s^(-1)时,绝热温升△T=103℃使得马氏体更容易发生塑性变形. Strain hardening behaviour and mechanism of a cold-rolled dual phase steel DPII80 under quasi-static tensile condition at a strain rate of 0.001 s-1 by electronic universal testing machine, and dynamic tensile condition at strain rates of 500 and 1750 s-1 by split Hopkinson tensile bar (SHTB) apparatus were systematically studied. According to the modified Swift true strain-stress model, the experimental data was regressed by using nonlinear fitting method, and strain hardening exponent in the modified Swift model was calculated by a modified Crussard-Jaoul method. The results revealed that there are two stage strain hardening characteristics of DPIIS0 steel at the strain rate range of 0.001--1750 s-I, the strain hardening ability of the stage I was enhanced with increase of strain rate, while the strain hardening ability of the stage Ⅱ was weak- ened, and the transition strain was decreased. The ferrite near the martensite regions formed cell blocks with dislocation structures, with a size of 90 nm, due to the limit of deformation compatibility,and the existence of geometrically necessary boundary (GNB) made DP1180 steel not instantly dam- aged under deformation at high strain rates. In addition, the adiabatic temperature rise of AT= 103℃ made martensite easy to have plastic deformation at a strain rate of 1750 s-1.
出处 《金属学报》 SCIE EI CAS CSCD 北大核心 2012年第10期1160-1165,共6页 Acta Metallurgica Sinica
基金 国家高技术研究发展计划项目2009AA03Z518 北京科技大学冶金工程研究院基础理论研究基金项目YJ2010-006资助~~
关键词 双相钢 高应变速率 应变硬化 修正的Crussard-Jaoul分析法 几何必需边界 dual phase steel, high strain rate, strain hardening, modified Crussard-Jaoulanalysis, geometrically necessary boundary
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