Abstract:

Electromagnetic heat effects can achieve crack arresting and strengthening of metal structures with half-embedding crack and embedding crack.In fact,hole defects often exist in castings and forgings.The effects of electromagnetic heat strengthening on hole defects were analyzed from theory and numerical simulation,and the current density and temperature distribution were derived while the current flowing around a sphere.The researches show that hole  defects can be treated as generalized embedding defects,and the application of electromagnetic heat strengthening and crack prevention is feasible.After current discharged,the current flows around the spherical cross-section in the direction perpendicular to the current.The temperature exceeds the melting point of the material immediately to form welded joints.Pressing stress reduces the stress concentration significantly, which inhibits the crack expanding when the hole defects are forced, therefore, this method can achieve the effect of crack arresting and strengthening.

Key words: electromagnetic heat, embedding crack, spherical hole, crack arrest

摘要：

电磁热效应可以实现含半埋藏裂纹、埋藏裂纹金属构件的止裂强化。针对实践中铸件和锻件内往往存在孔洞形式的缺陷,从理论和数值模拟角度分析了电磁热对其强化的效果,导出了球体绕流的电流密度和温度场分布。研究表明：孔洞缺陷可处理成广义埋藏裂纹缺陷,应用电磁热止裂强化是可行的。放电后,在垂直于通电方向,球形中截面上形成绕流现象,瞬间温度超过了材料的熔点,形成焊口,产生的热压应力显著降低了应力集中,从而抑制了孔洞缺陷受力时的扩展,达到了止裂强化效果。
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关键词: 电磁热, 埋藏裂纹, 球形孔洞, 止裂