温度对Zr—4合金低周疲劳性能的影响

The Effect of Testing Temperature on Low Cycle Fatigue Behavior of Zircaloy-4

研究了室温和４００℃去应力退火状态Ｚｒ－４合金对称拉－压低周疲劳行为。建立了循环和单调加载方式下Ｚｒ－４合金应力－应变曲线方程和循环应变幅－疲劳寿命之间的关系；分析了温度对Ｚｒ－４合金变形行为和疲劳性能的影响；讨论了高温疲劳寿命预测方法；根据疲劳断口ＳＥＭ观察结果，分析了Ｚｒ－４合金在室温和４００℃疲劳断裂方式的异同。结果表明，Ｚｒ—４合金室温下的循环应力－应变曲线表现为循环硬化，而４００℃下表现为循环软化；室温和４００℃下的循环应变幅－疲劳寿命关系分别为△εｐ·Ｎｆ０．７６６８＝４８．９４，△εｐ·Ｎｆ０．３６８９＝４．９８．

Symmetric tension-compression LCF Properties at RT and 400 t was studied fo zircaloy-4 at stress-relieved condition. The testing results include the relationships of stressstrain during cyclic and monotonic loading procedure,and the effect of testing temperature on cyclic deformation behavior and fatigue properties. The fatigue life prediction method for zircaloy at high temperature is also discussed. All these results were rationalized in term of fatigue fracture modes based on the SEM examination to fracture surfaces. The results show that cycle stress-strain curves of zircaloy- 4 behave as cycle hardening behavior at room temperature and cycle softening behavior at 400 ℃,respectively. The relationships of cycle strain range-fatigue life at RT and 400℃ are △εp·Nf0.7668= 48. 94 and △εp·Nf0.3689=4.98,respectively.