应变速率对304不锈钢塑性变形及马氏体转变行为的影响  

Influences of Strain Rate on Plastic Deformations and Martensitic Transformation Behaviors of 304 Stainless Steels

作　　者：湛利华 赵帅[1] 杨有良 常志龙 ZHAN Lihua;ZHAO Shuai;YANG Youliang;CHANG Zhilong(Research Institute of Light Alloy,Central South University,Changsha,410083;State Key Laboratory of Precision Manufacturing for Extreme Service Performance,Central South University,Changsha,410083;College of Mechanical and Electrical Engineering,Central South University,Changsha,410083)

机构地区：[1]中南大学轻合金研究院,长沙410083 [2]中南大学极端服役性能精准制造全国重点实验室,长沙410083 [3]中南大学机电工程学院,长沙410083

出　　处：《中国机械工程》2024年第12期2132-2138,2168,共8页China Mechanical Engineering

基　　金：国家自然科学基金(U2341273,U22A20190,52205435);湖南省自然科学基金(2022JJ40621);湖南省科技创新计划(2020RC4001);极端服役性能精准制造国家重点实验室自主课题(ZZYJKT2022-07)。

摘　　要：为研究0.5 mm厚304不锈钢室温条件下的塑性变形行为及马氏体转变规律,开展0.00067 s^(-1)、0.002 s^(-1)、0.01 s^(-1)、0.1 s^(-1)及1 s^(-1)五种不同应变速率下的单轴拉伸试验,并通过X射线衍射仪对各样品进行物相分析。结果表明:随着应变速率增大,材料的屈服强度明显上升,表现出应变速率强化效应;由于拉伸过程中塑性功转化为热能,马氏体转变受到抑制,抗拉强度略有减小。在真实应变小于0.27时,不同应变速率下的加工硬化率均呈下降趋势;而在真实应变大于0.27后,低应变速率下材料出现较为显著的二次硬化,这与材料内部的马氏体转变有关。为此,提出将马氏体相变动力学方程(Olson-Cohen方程)引入传统Johnson-Cook模型中,以表征不同应变速率拉伸过程中的二次硬化现象。不同应变速率下流变应力变化实际值与改进后的Johnson-Cook本构模型计算值预测精度分别为3.23%、3.42%、4.13%、4.09%及5.14%,并且改进模型相对于传统的Johnson-Cook模型能够更加准确地描述不同应变速率拉伸过程中的二次硬化阶段。To investigate the plastic deformation behaviors and martensitic transformation rules of 0.5 mm thick 304 stainless steels at room temperature,uniaxial tensile tests were conducted at five different strain rates of 0.00067 s^(-1),0.002 s^(-1),0.01 s^(-1),0.1 s^(-1) and 1.0 s^(-1),with subsequent X-ray diffraction(XRD)analysis for phase analysis.The results reveal a notable increase in yield strength with rising strain rate,indicating strain rate strengthening effects.Additionally,due to plastic work converting into heat during tensile processes,martensitic transformation was inhibited,resulting in a slight tensile strength reduction.Below a true strain of 0.27,work hardening rates decrease under varying strain rates.However,beyond this threshold true strain,significant secondary hardening occurs under low strain rates,which is attributed to the internal martensitic transformation.To address this phenomenon,the Olson-Cohen equation was integrated into the traditional Johnson-Cook model to characterize secondary hardening during tensile processes across different strain rates.The improved Johnson-Cook model achieves high accuracy in predicting rheological stress changes,with deviations of 3.23%,3.42%,4.13%,4.09%,and 5.14% respectively compared to experimental values,effectively capturing the secondary hardening stage at various strain rates.

关 键 词：304不锈钢 应变速率 Johnson-Cook模型 马氏体转变 

分 类 号：TG142[一般工业技术—材料科学与工程]