304不锈钢两阶段载荷模式下的疲劳寿命

FATIGUE LIFE OF 304 STAINLESS STEEL UNDER DIFFERENT LOADING MODES WITH TWO PHASES

对 3 0 4不锈钢进行一系列单轴、扭转、比例和非比例循环载荷变化的两阶段低周疲劳实验 ,比较各阶段载荷下的循环特性。结果表明在第一阶段载荷下 ,材料在开始几个循环表现出软化特性 ,在路径转化时有交错强化现象 ,而在圆路径下产生明显的附加强化。试验结果表明 ,这种强化对疲劳寿命有明显影响 ,使两段载荷的总疲劳损伤小于 1。文中比较了线性损伤律和几个非线性损伤律 (Manson的双线性损伤律、损伤曲线方法、Morrow模型 )的寿命预测结果 。

A series of low-cycle fatigue experiments were conducted on 304 stainless steel under uniaxial, torsional, proportional and nonproportional loading with two phases. It is shown that the material displayed cyclic softening behavior under first phase loading, while an additional hardening was observed following the second phase loading path due to the cross hardening and nonproportional hardening effects between two loading paths. The nonproportional additional hardening was more obvious in the circle path. The test results show that the additional hardening plays obvious role in the fatigue life and the damage accumulation. The damage summation of two phase loadings was less than 1. The comparisons between experiment and prediction were made based on the linear and nonlinear damage rules (the double-linear damage rule of Manson, damage curve approach, the plastic work model of Morrow). All the models present unconservative predictions.