Zr-4合金常规力学行为研究与低周疲劳断口分析

Study on Mechanical Behaviors and Low Cycle Fatigue Fracture Analysis of Zr-4 Alloy

对Zr-4合金开展了常温与400℃高温下的常规力学行为研究,获得了两种温度下材料的单调R-O(Ramberg-Osgood)本构模型。通过测定不同温度下的弹性模量和泊松比,得到了它们随温度的变化关系。同时对Zr-4合金热膨胀系数进行了测定。对常温与400℃高温下低周疲劳试样进行了扫描电镜观察和断口分析,结果发现Zr-4合金低周疲劳断裂以穿晶断裂为主并伴随有疲劳辉纹和二次裂纹出现。

A series of investigations on the normal mechanical behaviors of Zr-4 at room temperature and 400°C elevated temperature were carried out. R-O (Ramberg-Osgood) monotonic constitutive models at the two different temperatures were given. The effects of temperature on elastic modulus and Poisson ratio of Zr-4 alloy, as well as the heat expansion coefficient, were investigated. Microstructure SEM features were discussed systematically to the LCF (Low Cycle Fatigue) specimens according to the LCF experimental results at room and 400°C elevated temperature. The results show that the failure mode is a type of transgranular fracture accompanied with some wavy fatigue striations and quadratic cracks.