带有半埋藏空间裂纹的Cr12构件电磁热止裂分析

对带有半埋藏环形裂纹的Cr12标准拉伸试件进行了电磁热止裂研究.通过ZL-2型放电装置实现了半埋藏空间裂纹的止裂实验,采用微机控制电子万能试验机完成了止裂前后试件拉伸性能测试,同时计算了电磁热止裂前后应力强度因子的变化;建立了超强脉冲电流放电瞬间,环形裂纹尖端附近电流绕流、温度场和热应力场的数值分析模型,通过热-电耦合和热-机械耦合两个过程得到了脉冲放电瞬间拉伸试件中的电流矢量场、温度场和热应力场.研究表明:脉冲电流放电瞬间,围绕裂纹尖端金属熔化,钝化了裂尖,并围绕裂尖形成了热压应力场,得到了超细化的金属组织,止裂后抗拉强度得到了提高,达到了止裂的目的.

ANALYSIS ON CRACK ARREST BY ELECTROMAGNETIC HEATING IN Cr12 COMPONENTS WITH SPATIALLY HALF-EMBEDDING CRACKS

The crack arrest by electromagnetic heating is studied in tension test samples of Cr12 with half-embedding round cracks. The experiments of spatial half-embedding crack arrest are aonducred on the ZL-2 equipment. The tension test is applied using pc-control universal tester to tension test piece with crack before and after crack arrest.The stress intensity factor is calculated from beginning to end and the current, temperature and stress field have been founded at the moment that pulse current is applied. In analysis, the finite methods have been,The current vector diagram, temperature field and thermal stress field are obtained in test piece. The analysis process is composed of thermal-electrical coupling and thermal-mechanical coupling. All surveys show: After crack prevention, the metal around the round crack tips melts, the crack tip is passivation, the thermal compressive stress is formed, and the super-fine metallography structure is gained. The intensity of resisting tension gets improved after crack arrest. So the goal of crack prevention can be reached.