摘要
通过对U71Mn轨道钢和 3 16L不锈钢室温下单轴应变控制和应力控制循环的实验研究 ,就两种材料的应变循环特性和棘轮行为进行研究和比较。讨论应变循环下应变幅值和平均应变的大小及其历史对应变循环特性的影响以及应力循环下应力幅值和平均应力的大小及其历史对棘轮行为的影响 ,同时还讨论了应变循环与应力循环间的交互作用。研究中着重对两种材料的循环特性进行比较 。
An experimental study was carried out for the cyclic behavior of U71Mn rail steel and 316L stainless steel subjected to uniaxial strain and stress cycling at room temperature. The effects of cyclic strain amplitude, mean strain and their loading histories on the strain cyclic characteristics were studied. In the meantime, the effects of stress amplitude, mean stress and their histories on the ratcheting of the asymmetrical stress cycling were also analyzed. The interaction of strain cycling and stress cycling was discussed, too. In the study, the strain cyclic behavior and ratcheting of the two steels were compared especially. The results show that, under the strain cycling, U71Mn rail steel features almost no cyclic hardening or softening and its strain cyclic characteristics hardly depend on the loading history. However, 316L stainless steel characterizes significantly cyclic hardening and its strain cyclic characteristics depends not only on current load case, but also greatly on the load history. 316L stainless steel has an obvious memorization for the maximum strain amplitude of the load history. These phenomena must be taken into account in the constitutive modeling. The mean strain and its history have almost no effect on the strain cyclic behaviors of the two researched metals. Ratcheting is a special characteristic of the material presented in the asymmetrical stress cycling. Under the stress cycling, the ratcheting behaviors of the two metals depend not only on current load case, but also on the previous history. The ratcheting strain and its rate increase with the increase of mean stress and stress amplitude. The prior higher mean stress and stress amplitude cycling can restrain the ratcheting behavior of subsequent lower mean stress and stress amplitude cycling. A prior stress cycling results in not only a mean strain in the subsequent strain cycling, but also some variation of strain cyclic properties. After the prior stress cycling, U71Mn rail steel presents obvious cyclic softening, but 316L stainless steel still presents cyclic hardening. However, a prior strain cycling restrains the ratcheting behavior of subsequent stress cycling for the two metals. The ratcheting strain rates of the materials in stress cycling without prior strain cycling are higher than that with prior strain cycling. These conclusions are useful to establish constitutive model for the cyclic behavior of the materials.
出处
《机械强度》
CAS
CSCD
北大核心
2002年第4期608-612,共5页
Journal of Mechanical Strength
基金
国家自然科学基金 (1 9772 0 4 1 )
四川省跨世纪学术带头人培养基金资助
