脉冲放电对6061铝合金焊接接头组织及力学性能的影响

Effect of pulse discharge on microstructure and mechanical properties of 6061 aluminum alloy welded joint

采用电磁热止裂强化方法对6061铝合金焊接接头进行强化研究,通过ZL-2型超强脉冲放电装置对焊接接头进行放电强化实验,并对焊接接头力学性能、硬度和显微组织进行对比分析。对含埋藏孔洞缺陷的焊接接头进行了脉冲放电数值分析,得到放电瞬间的温度场和热应力场。结果表明:放电瞬间焊接接头缺陷处温升达到材料熔点,孔洞钝化并产生有利的热压应力;经放电处理后,焊接接头Mg_2Si强化相增多,且晶粒变的细小,焊接接头处力学性能和显微硬度均得到提高。

The strengthening of 6061 aluminum alloy welded joints was studied by the method of electromagnetic heating crack arrest.Discharge enhancement experiment of welded joint was carried out by ZL-2 type pulse discharge device,and the mechanical properties,hardness and microstructure of welded joints were compared and analyzed. The temperature field and thermal stress field of the discharge were obtained by the numerical analysis of pulse discharge on welded joints with buried hole defects. Results show that the temperature of the defect of the welding joint can reach the melting point of the material at the discharge moment,meanwhile,the hole is passivated and the favorable thermal stress is produced. After discharge treatment,the Mg2 Si strengthening phases of the welded joint increase,and the grain size is refined. The mechanical properties and microhardness of the welded joint are both improved.