摘要
采用ＭＴＳ材料试验机对正大状态的４０ＣｒＡ钢在二维循环复杂应变路径下的流动特性和强化进行了系统的实验研究。对于特定的循环应变路径，当应变幅值较小时，材料多表现为循环弱化；随着应变幅值的增加，循环弱化的现象逐渐消失，在某些路径下甚至表现为循环强化，当从一种比例路径下的循环稳定状态进入另一种比例路径下循环时，存在瞬时附加强化并随之产生缓慢的弱化。在非比例循环加载条件下，材料的强化与路径形状密切相关。不发生卸载的圆形路径未表现出最显著的强化，而应变路径方向的改变及其频率成为影响强化的主要因素。实验表明对于所采用的材料，应变的幅值和方向的变化所造成的强（弱）化间存在耦合。
A systematic experimental research on the flow and hardening properties of nor-malized 40CrA steel subjected to biaxially nonproportional cyclic loading was conducted on MTS809 material testing machine, In most cases,the material performs cyclic softening for the givencyclic strain path when the strain amplitude is small,and this kind of softening decreases and evenchanges to hardening as the strain amplitude in creases.Instantaneous hardening occurs and is fol-lowed by a transient , but subsiding softening when the cyclic strain path changes. It was observedthat the hardening of the material depends strongly on the shape of cyclic strain path. An interestingphenomenon is that the 90°out-of-phase strain path,that involves no unloading,does not yieldmarked hardening. The variation of the strain path direction and its frequency were observed as themain factor to determine the material hardnening. The coupling between the hardening induced bystrain amplitude and that by strain path was detected.The memory of the material to the nonpropor-tional cyclic loading hestory and the validity of Lensky’ s hypothesis of local determinability were al-so invesgated.
出处
《重庆大学学报（自然科学版）》
CAS
CSCD
1994年第2期17-25,共9页
Journal of Chongqing University
关键词
金属材料
循环载荷
塑性流动
钢
metallic materials
nonproportional cyclic loading
plastic flow
hardening
experimental research
