室温下不锈钢的多轴时相关循环变形行为

Time-Dependent Cyclic Behavior of Stainless Steel under Multiaxial Loading at Room Temperature

对1Cr18N i9不锈钢在室温下的非比例多轴时相关循环应变特征和棘轮行为进行了试验研究,以考察应变率、应力率和加载路径对其循环变形行为的影响.结果表明,1Cr18N i9不锈钢的循环应变行为和棘轮行为对应变率、应力率很敏感,具有时相关特点:在多轴应变循环下,其最大等效应力随应变率增大而增大;在棘轮试验中,其轴向棘轮应变则随着应力率减小而增大.此外,加载路径对1Cr18N i9不锈钢的循环粘塑性变形行为也有较大影响:多轴应变循环下,在所采用的直线、菱形和圆形3种加载路径中,圆形路径引起的非比例附加硬化程度最高,其次是菱形路径.然而,试验发现,在多轴棘轮试验中,圆形路径产生的棘轮应变高于菱形路径.

The time-dependent cyclic straining characteristic and ratcheting behavior of 1Cr18Ni9 stainless steel were investigated experimentally under non-proportional multiaxial cyclic loading at room temperature to research its dependence upon straining rate, stressing rate and loading paths. The results show that the cyclic straining behavior and ratcheting deformation of this material are markedly dependent on straining and stressing rates and have a time-dependent characteristic： the maximum equivalent stress increases with the increasing of straining rate under multiaxial straining, while the axial ratcheting strain increases with the decrease of stressing rate. Furthermore, loading paths have a great effect on the cyclic viscoplasticity behavior of the material： under multiaxial straining, the circular path causes the highest degree of non-proportional strain hardening in linear, rhombic and circular non-proportional loading paths adopted in the tests, then the rhombic path. Under multiaxial ratcheting tests, however, the circular＇ path brings about a greater ratcheting strain than the rhombic path.