焊接热影响区疲劳裂纹扩展的微观行为

Micro-behaviour of fatigue crack growth in welding heat-affected zone

关键词:  疲劳  扫描电子显微镱  焊接

Key words:  fatigue  scanning electron microscope  weld

摘要:

通过配置疲劳加载台的扫描电子显微镜,对16MnR钢焊接热影响区(HAZ)疲劳裂纹扩展行为进行了直接动态观察,提出了疲劳裂纹"突跃-转折-分叉"扩展模型,并且建立了包括局部应力强度因子,材料疲劳特性参数和损伤特征长度在内的疲劳裂纹扩展速率计算公式,按该模型计算的结果与试验结果进行了比较,二者基本吻合。

Abstract:

Direct observation was accomplished on the fatigue crack growth behaviour in 16MnR steel weld HAZ with SEM and the fatigue loading equipment. Based on the observed results, an intermittent-kinked-forked fatigue crack growth model was developed and a calculating formulation for fatigue crack growth was established. The formula incorperates local strecs intensity factor, mechanical, cyclic and fatigue properties as well as a damage length parameter. The predicted values of the model were compared with the experimental data and they are in a good agreement.