Zr-4合金拉-扭复合比例加载条件下的低周疲劳特性

Biaxial Low Cycle Fatigue Properties of Zircaloy-4 under Tension-Torsional Proportioal Loading

研究了Zr-4合金管材在主应变比ε3／ε1=-0.8，-0．7，-0．6，-0．5和等效应变幅0．5％，0．7％，0．8％，0．9％，1．0％，1．1％下的低周多轴疲劳性能。结果表明：在拉-扭比例加载过程中，再结晶状态Zr－4合金表现为初期短暂硬化，随后持续软化的特性。Zr－4合金的循环等效应力-应变曲线位于单调曲线的上方，表现为循环硬化。主应变化对循环硬化曲线没有影响。相同Mises等效应变幅下，应变比越大，疲劳寿命越低。双轴疲劳过程中，Zr－4合金Mises等效应变幅与疲劳寿命之间呈指数关系。

Biaxial low cycle fatigue properties of the alloy Zr-4 have been studied for the principal strain ratios (ε3/ε1) of-0. 8. -0. 7, -0. 6, -0. 5 and the equivalent strain ranges of 0.5%. 0.7%, 0. 8%, 0. 9%, 1.0%, 1. 1%. The results show that the alloyZr-4 displays cyclic deformation hardening followed by softening. The cyclic Mises' equivalent stress-strain curve lies above the monotonic one for the alloy Zr-4 under proportional loading. The effect of strain ratio on cyclic deformation behavior is small. The largerthe strain ratio, the lower the fatigue lifetime for the same Mises' equivalent strain range. The relationship between fatigue lifetimeand the Mises' equivalent strain range fits an exponent law.