中文摘要：

选择2Cr13材料,通过对接焊方法在焊接接头处预制埋藏裂纹,采用超声波无损检测对埋藏裂纹位置及尺寸进行标定;采用热—电耦合焦耳热问题的数值分析方法,计算出放电瞬间焊接接头内圆形埋藏裂纹的温度场,并求得止裂后焊接接头内的残余应力场。通过ZL-2型超强脉冲放电装置对焊接接头进行电磁热止裂强化试验,对止裂前后埋藏裂纹裂尖附近微观组织进行分析,对比测试止裂前后试件的抗弯、拉伸等力学性能。研究结果表明：止裂瞬间,焊接接头中埋藏裂纹裂尖处温升超过金属熔点,裂尖熔化、钝化,达到阻止裂纹扩展的目的;同时,止裂后裂尖附近微观组织明显细化,出现强韧性均好的白亮组织,进一步阻止了裂纹的扩展;止裂后焊接接头抗弯强度提高18.0%,抗拉强度提高11.7%,断后伸长率提高34.6%。研究证实,脉冲放电实现了2Cr13焊接接头内埋藏裂纹止裂,并提高了焊接接头的力学性能。

英文摘要：

Embedding crack is prefabricated in 2Cr13 welding joints which are generated by butt welding method, and its location and size are demarcated by ultrasonic nondestructive testing. Temperature field around crack which is embedding and circular in welded joints at the moment of pulse current discharge is calculated by thermoelectric coupling numerical simulation methods. Meanwhile residual stress field is analyzed after crack arrest. Crack arrest experiments on specimens with welding joints are carried out by ZL-2 equipment. Microstructure of buried crack tip is analyzed and the properties of flexural behavior and tension are tested before and after crack arrest. The study shows that the crack tip is melting and passivated due to the temperature of crack tip over its melting point at the time of discharge. Thus, the further expansion of crack can be prevented. The microstructure near crack tip refined obviously and white layer structure which has a good strength and toughness is produced, further it prevents the crack from the propagation. The flexural strength of welded joints increases by 18.0%, tensile strength increases by 11.7% and fracture elongation increases by 34.6% after crack arrest by electromagnetic heating. The study confirmed that the pulse current discharge achieves the goal of buried crack arrest in 2Crl 3 welding joints and improves the mechanical properties of welded joints.