轴对称金属模具电磁热裂纹止裂温度场的分析

选择带有半埋藏环形裂纹的金属凹模为研究对象,通过金属凹模内外环面均匀通入强脉冲电流,应用电磁热效应实现了金属凹模中环形裂纹的止裂。采用复变函数的方法求解了脉冲电流放电瞬间裂纹尖端附近的温度场。由于脉冲电流放电瞬间,裂尖处电流绕流的热集中效应,在金属凹模内部,环形裂纹尖端金属的温升超过熔点,金属熔化,在金属凹模内部沿着环形裂纹尖端形成堆焊,致使环形裂纹尖端的曲率半径瞬间增大,阻止了干线裂纹源的开裂趋势。

ANALYSIS ON THE TEMPERATURE FIELD IN AN AXIAL SYMMETRIC METAL DIE WHEN USING ELECTROMAGNETIC HEATING FOR CRACK ARRESTING

A metal die with a half-embedded round crack is selected as object. The crack arresting is accomplished using electromagnetic heating by a pulse current discharge through the inside and outside of the die. The complex function method is used to solve for the temperature field around the crack tips in the metal die with half-embedded round crack at the moment when the current pulse is switched on. The temperature around the crack tip rises instantly above the melting point of the metal as a result of the heat concentration effect when the current pulse discharge and the metal melts instantly near the crack tip. Small welded joints can be formed in a small spherical region around the round crack tips inside the metal die. The curvature at the end of the half-embedded round crack increases instantly, so the formation of the main crack is arrested.