1Cr18Ni9不锈钢高温单轴时相关棘轮行为研究

在室温、250℃、500℃和650℃四种温度下对1Cr18Ni9不锈钢材料的单轴应变循环特性及其时相关棘轮行为进行了实验研究,以讨论不同加载速率、加载波形和峰值应力保持时间对材料棘轮行为的影响。实验结果表明:在室温下,材料呈现出弱的循环软化特性和渐进型棘轮变形行为,并对加载速率和峰值应力保持时间具有强烈依赖性;在250℃、650℃下,因材料的循环硬化加快而使其棘轮行为较快趋于安定,但棘轮变形大小仍一定程度依赖于加载速率和保持时间;在500℃温度下则由于动态应变时效的影响没有明显的棘轮行为发生。研究得到一些有助于后续建立时相关本构模型的结论。

UNIAXIAL TIME-DEPENDENT RATCHETING BEHAVIORS OF 1CR18NI9 STAINLESS STEEL AT ELEVATED TEMPERATURES

The uniaxial cyclic straining characteristics and time-dependent ratcheting behavior of 1Cr18Ni9 stainless steel were studied experimentally at room temperature, 250℃, 500℃ and 650℃, to investigate the dependence of the ratcheting upon loading rates,loading wave forms and peak stress holding times. The experimental results show that at room temperature, the material presents weak cyclic softening and its ratcheting behavior is strongly affected by the loading rate and hold-time; at 250℃ and 650℃, the ratcheting behavior of the material shakes down quickly due to the cyclic strain hardening, whereas the magnitudes of the ratcheting strain is still dependent on the loading rate and hold-time to some extent; at 500℃, no ratcheting occurs due to the effect of dynamic strain aging. Some conclusions obtained are useful for the construction of a sound constitutive equation.