不同控制模式对单轴拉伸试验结果的影响

为了研究横梁位移控制和引伸计控制对材料拉伸试验结果的影响，以应变强化9%的奥氏体不锈钢S30408为研究对象，在20 ℃和-196 ℃下采用2种控制模式进行拉伸试验，并通过有限元模拟比较2种控制模式对拉伸结果的影响.结果表明：当横梁位移控制时，试样的实际变形速率小于引伸计控制时试样的变形速率，且标准中的修正公式不能有效消除由于变形速率引起的误差.在20 ℃时，横梁位移控制代替引伸计控制可以满足工程精度要求；在-196 ℃时，两者差异较大，建议采用引伸计控制.

Effect of different control modes during tensile experiment

To investigate the difference between tensile tests under displacement control mode and extensometer control mode, tensile tests of 9% cold stretched S30408 austenitic stainless steel were performed at 20 ℃ and -196 ℃ with each control mode respectively and using finite element simulation to find the connection of two different modes. Results show that the actual strain rate in displacement control mode is lower than that in extensometer control mode and the standard correction formula cannot eliminate the error caused by the difference between actual strain rates of specimen in different modes.The results of two different modes are nearly the same at 20 ℃, but have an nonnegligible difference at -196 ℃. Using displacement control mode instead of extensometer control mode can also meet the engineering requirements at 20 ℃, but it is advised to use extensometer control mode at -196 ℃.