高应变率时的转变动力学测试及组织形貌观察

Test Method of Transformation Kinetics and MorphologyObservation at High Strain Rate

采用自行设计的双径试样 ,提出了高应变率时的转变动力学测试方法 ,并测定了奥氏体不锈钢在低温高应变率时应变诱发马氏体转变的动力学曲线 ,观察了不同变形阶段的组织形貌 .结果表明 :当应变量小于 9%时 ,高应变率时的应变诱发马氏体转变量低于低应变率时的 ;当应变量大于9%时 ,则相反 .观察到高应变率时应力平台与硬化阶段的TEM组织形貌分别为孪晶与断续的马氏体 .

Test method of transformation kinetics is developed at high strain rate using twin specimens. The transformation kinetics of strain induced martensite has been measured and microstructure morphology is also observed at high strain rate for austenitic stainless steel. Experimental results show that transformation volume fraction of martensite at high strain rate is less than that at low strain rate when the strain is less then 9%, but is higher than that at low strain rate when the strain is over 9%. TEM morphology of the twin specimens at stress plateau stage and martensite section at hardening stage has been observed.