Abstract:

Strengthening welded joints of dissimilar materials
was studied based on electromagnetic heating crack arrest.
Through the numerical simulation method the welded joints with embedding elliptical
crack were discharged,the thermal stress field was obtained and the residual stress was also obtained via cooling to room temperature.The simulation results show that at the time of pulse current discharge in welded joints with crack the temperature at the place of crack tip is beyond its melting point,meanwhile the crack tip blunts and generates compressive stress which is good for workpiece.Through studying the electromagnetic heating crack arrest
experiments for welded joint of Q235 and 1Cr18Ni9,it proves that when specimen is discharged the mechanical property of welded joints will be better than before,the tensile strength is improved by 19.4% and the impact toughness is improved by 12.07%.

Key words: welded joint, embedding crack, pulse current discharge, crack arrest, mechanical property

摘要：

采用电磁热止裂强化方法对异种材料焊接接头进行强化研究,对含椭圆形埋藏裂纹缺陷的焊接接头进行了脉冲放电数值分析,得到放电瞬间的热应力场和冷却到常温时的残余应力场,结果表明,脉冲放电瞬间焊接接头中的裂纹尖端温升超过材料熔点，裂尖钝化并产生了有利的残余压应力;对Q235和1Cr18Ni9焊接接头进行了电磁热强化试验研究,结果表明,试件通过放电强化，焊接接头的力学性能得到改善，抗拉强度提高19.4%，冲击韧性提高12.07%。
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关键词: 焊接接头, 埋藏裂纹, 脉冲放电, 裂纹止裂, 力学性能