含半埋藏共线双裂纹的Cr12合金钢试件电磁热止裂分析

Analysis of Crack Arrest in Cr12 Alloy Steel Sample with Half-embedding In-line Crack Using Electromagnetic Heating Effect

应用ZL-2超强脉冲电流发生装置对带有预制双平行共线半埋藏裂纹的拉伸试件进行了脉冲放电止裂,放电后裂纹尖端熔化并形成高压应力区,使裂纹尖端钝化,达到了止裂的目的。采用数值模拟确定了止裂工艺参数,并确定了脉冲电流作用瞬间裂纹尖端的温度场和热应力场。研究结果表明:在合适的脉冲放电电压下,电磁热效应实现了空间半埋藏裂纹线形裂尖的钝化,并围绕两个共线裂纹尖端形成了热压应力场,同时实现了裂尖附近组织细化,可提高裂纹扩展的延展功,从而可减缓裂纹的扩展。

A crack of standard tension test piece with prepared half-embedding in-line crack was arrested by pulse current discharge from ZL-2 pulse current generating equipment. After discharging, the crack tip was melted, and a high thermal compressing stress area was formed around it, thereby passirating the crack tip for crack arrest. A numerical simulation was made to determine the technological parameters of crack arrest, the thermal stress and temperature fields around the crack tip at the moment of pulse current discharge. The research results show that, in the case of appropriate pulse discharge voltage, the tip of half-embedding in-line crack can be passivated using the electromagnetic thermal effect, a thermal compressing stress field is formed around the in-line crack tip, the metal structure around crack tip is fined, and the spreading work of crack extension can be improved to solve the crack extension.