屈服强度与裂纹形成寿命的关系

 一般认为材料的疲劳损伤和裂纹形成是由循环局部塑性应变引起的。因此,提高材料对微量塑性变形的抗力（为屈服强度、比例极限）,将有利于提高其疲劳形成门槛值,延长裂纹形成寿命,从而延长疲劳总寿命。然而,材料的微量塑性变形抗力对疲劳性能的影响,仍未予以足够的重视。所以在一些单位的产品设计和生产检验中,似未规定对屈服强度的明确要求。

ON THE RELATIONSHIP BETWEEN YIELD STRESS AND FATIGUE CRACK INITIATION LIFE OF METALS

Based on the recent research on fatigue crack initiation life, it is shown that the yield stress of metals has great effects on the fatigue crack initiation (FCI) threshold and life in long life range.Aluminum alloys and high strength steels with higher yield stress display higher FCI threshold and much longer FCI life, especially, in long life range under both constant and variable amplitude loading.Thus, the total fatigue life of metals with higher yield stress is longer.Consequently, the structural alloys with high yield stress should be selected in the design of structure elements. Moreover, the yield stress should be checked during the production of elements.