SS304不锈钢高温非比例多轴加载下时相关循环变形行为的实验研究

EXPERIMENTAL STUDY ON NON-PROPORTIONALLY MULTIAXIAL TIME-DEPENDENT CYCLIC DEFORMATIONS OF SS304 STAINLESS STEEL AT HIGH TEMPERATURE

在973K下,对SS304不锈钢多轴循环加载下的时相关应变循环特性和时相关棘轮行为进行了实验研究.揭示了材料在不同加载路径、不同加载速率以及不同保持时间下的循环软/硬化特性和棘轮变形行为.结果表明:在高温下,材料的循环软/硬化和棘轮变形均体现出明显的时相关效应,即其循环变形行为不仅强烈依赖于加载速率,而且还明显依赖于保持时间;另外,材料的变形行为在高温下也具有强烈的加载路径依赖性.研究得到了一些有助于后续建立时相关本构模型的结论.

The time-dependent strain cyclic characteristics and ratcheting behavior of SS304 stainless steel were studied by experiments under non-proportionally multiaxial cyclic loading and at 973 K. The effects of loading path, straining/stressing rate and holding-time at peak/valley of each cycle on cyclic softening/hardening behavior and ratcheting were discussed. It is shown from experimental results that the cyclic softening/hardening behavior and ratcheting of the material are characterized by apparent time-dependence, i.e., the cyclic deformation behaviors depend not only greatly on loading rate, but also apparently on holding-time, besides, the ratcheting behavior of the material also presents a great dependence on loading path at high temperature. Some results obtained are helpful to construct a time-dependent constitutive model of ratcheting.