热处理对裂尖不同塑性变形状态下工业纯钛疲劳裂纹扩展行为的影响

Effect of Heat Treatment on Fatigue Crack Growth Behavior of Commercially Pure Titanium under Different Crack Tip Deformation Conditions

开展热处理工业纯钛TA2在不同载荷水平下疲劳裂纹扩展实验,考虑裂尖塑性变形程度,研究疲劳裂纹扩展规律以及热处理状态对疲劳裂纹扩展不同阶段的适应性。结果表明,不同疲劳载荷下热处理对疲劳扩展速率产生不同的影响。A类加载热处理后的疲劳裂纹扩展速率下降是由于近门槛区有效载荷的降低,以及近门槛值的提高。B类加载下热处理对有效载荷以及裂尖塑性变形几乎没有什么影响。C类与D类加载下热处理后裂尖塑性变形受到限制,而导致疲劳裂纹扩展速率下降。

Fatigue crack propagation experiment of commercially pure titanium TA2 under different load levels after heat treatment was carried out.With consideration of the degree of plastic deformation of crack tip,the adaptability of heat treatment state to different stages of fatigue crack growth was investigated.The results show that heat treatment has different effects on the fatigue crack growth rate under different loading conditions.The decrease of fatigue crack growth rate with heat treatment in loading A condition is due to the reduction of the effective load near the threshold region and the increase of the near threshold value.Heat treatment in loading B condition has little effect on the effective load and the plastic deformation of crack tip.The plastic deformation of crack tip is restricted after heat treatment under loading C and D conditions,which decrease the fatigue crack growth rate.