电热止裂相变应力及其对止裂效果的影响

Phase Transformation Stress and Its Influence for Arresting Crack Propagation Using Electro-heating Effect

对含裂纹的45钢钢板进行了电热效应裂纹止裂(简称电热正裂)实验研究,发现电热止裂后的裂纹尖端附近发生了相变,并对相变组织进行了实验观察。针对裂尖处的相变区域,进行了相变应变的X射线衍射实验测定,采用Eshelby等效夹杂模型,利用等效夹杂理论进行了放电后裂尖处的相变应力场的理论分析计算。计算结果表明,在裂尖处的相变区域,形成了相变压应力场。分析了相变压应力对止裂效果的长效影响,发现相变压应力对裂纹扩展的阻碍影响是非常明显的,其对裂纹扩展速率降低的影响更是显而易见,起到了长期限制裂纹扩展的作用。研究结果表明,电热止裂技术既具有理论的可行性,也具有实际应用的实效性。

An experimental investigation of arresting crack propagation by pulse discharging to a 45# steel plate with crack was shown herein.Through the microstructure analysis near crack tip after crack prevention by using electromagnetic heating effect,it is found that the phase transformation has been occurred.Also,the residual strain of phase transformation near crack tip has gotten by X-ray diffusion method.The theoretical calculation of the phase transformation stress was finished by Eshelby＇s model of imaginary cutting method.The affection of the residual stress on the crack propagation was discussed.It is found that the residual stress will have a long term effect for crack prevention.The results obtained show that the technique of arresting crack propagation by using electric magnetic heat effect has both academic feasibility and practicability.