304不锈钢箔材在不同应变速率下的拉伸性能研究

304不锈钢是一种常用的奥氏体不锈钢.在拉伸应变过程中，应变速率的变化会诱发马氏体转变量和转变速率，以及内部组织滑移线、位错、层错、形变孪晶密度的转变量和转变速率的不同，从而表现出不同的应变硬化行为.本文针对0.1 mm厚度304奥氏体不锈钢箔材，从断后伸长率，断面收缩率，屈服强度，抗拉强度及硬化指数5个方面，研究了室温条件下不同应变速率对其拉伸性能的影响.实验结果表明：马氏体转变理论同样适用于304奥氏体不锈钢箔材, 且0.1 mm厚度304不锈钢存在“越薄越脆，越小越强”的尺寸效应现象；同时，0.1 mm厚度304奥氏体不锈钢箔材拉伸力学性能随应变速率的变化主要表现在以下几方面：断后延伸率和断面收缩率均随着应变速率的增加而降低；低应变速率时，随着应变速率的增加屈服强度增大，而抗拉强度随应变速率的提高呈现减弱的相反规律；高应变速率下，304奥氏体不锈钢的强度主要由材料本身性能决定，应变速率的改变对强度的影响较小；准静态低应变速率下，硬化指数随应变速率增大而升高，较高应变速率下，硬化指数与应变速率变化无关.

Studies on the tensile properties of 304 stainless steel foil at different strain rates

304 stainless steel is a commonly used austenitic stainless steel. In the process of tensile deformation, different strain rate may induce the amount of transformation and transformation rate of martensite, as well as the slip lines, dislocations, stacking faults, deformation twins, resulting in different strain hardening behaviors. Effects of strain rate on the elongation, reduction of area, yield strength, tensile strength, and hardening index of 304 austenitic stainless steel foil with 0.1 mm thickness at room temperature are investigated. The experimental results show that the macroscopic martensitic transformation theory is applicable for 304 austenitic stainless steel foil after fracture and the elongation and the reduction of area of the specimen decreases with the increase of strain rate. When strain rate is low, the tensile strength increases with the increase of strain rate, while the yield strength shows the opposite rule. At high strain rate, the strength of 304 austenitic stainless steel is mainly determined by the properties of the material itself, and the strain rate change has little effect on the strength. Meanwhile, the influence of strain rate on the hardening index is unrelated to the tensile state.