织构对Zr-4合金循环变形行为的影响

研究了织构对Zr-4合金循环变形行为的影响及其作用机制。结果表明，(1)合金的低周疲劳寿命遵循Coffin—Manson关系N^(β)f△εpC。在给定△εp时，轧向的寿命比横向的长。随△εp的降低，两个方向的疲劳寿命差别增大；(2)在低应变幅，合金表现为循环软化直至疲劳破坏在高应变幅，循环变形的初期表现为循环硬化，随后是循环软化直至疲劳破坏在应变幅恒定时，随着循环次数的增加，晶粒发生转动，使晶粒有更高的Schmid因子；(3)半寿命时的σs随εp的变化遵循乘幂关系σs=K^sε(^n^s),σid随σp的变化则遵循对数关系σid=K^blnεp Cb；(4)轧向和横向之间循环变形行为的差别是由于织构效应的缘故。

Effect of Texture on Cyclic-deformation Behavior of Zircaloy-4

In this paper, effect of texture on cyclic-deformation behavior of Zircaloy-4 has been investi gated. The results indicate that (1) the alloy obeys the Coffin-Manson relation (bfNpeD= C), the low-cycle fatigue life in the rolling direction is higher than that in the transverse direction at a given peD, and the life difference between both directions becomes larger with lowering the peD;(2)the alloy shows cyclic- deformation softening till fracture under low strain amplitude, showing cyclic-deformation hardening in the early stage and then cyclic-deformation softening till fracture under high strain amplitude, and the grains would rotate with the cyclic-deformation going on at a given amplitude where these grains have higher Schmid factor; (3)ssat half-life obeys the power law relation ss=snpsKe, and ibs obeys the logarithmic relation ibs=pbKeln bC;(4) the cyclic-deformation behavior difference in both directions stems from the texture effect. Finally, the mechanism on texture effect has been discussed in detail.