AZ91磁控A-TIG焊电弧形态及焊接接头组织性能

为了分析磁场和活性剂对AZ91镁合金焊缝组织性能的影响规律并探究相应的作用机理,在A-TIG焊接过程中施加纵向交流磁场,采用高速摄影技术观察并拍摄电弧运动形态,对焊缝进行硬度、显微组织和物相组成分析.结果表明,当磁场电流为1.5 A、磁场频率为50 Hz、焊接电流为80 A、涂覆量为3 mg/cm~2时,焊缝硬度最大值为68.88 HV.在合适的磁场参数和活性剂配比下,电弧挺度最大,电弧收缩明显,此时电弧的搅拌作用致使晶粒显著细化,且析出相Al_(12)Mg_(17)明显增多,这对改善焊接接头的力学性能具有积极作用.

Arc shape of magnetic field controlled A-TIG welding for AZ91 alloy and microstructure and properties of welded joint

In order to analyze the effect laws of magnetic field and active agent on the microstructure and mechanical properties of the welded seam of AZ91 magnesium alloy and explore the corresponding action mechanism, the longitudinal AC magnetic field was applied in the A-TIG welding process, the morphologies of arc motion were observed with the high-speed photography technology, and the hardness, microstructure and phase constitute of welded seam were analyzed. The results show that when the magnetic field current is 1.5 A, the magnetic field frequency is 50 Hz, the welding current is 80 A and the coating amount is 3 mg/cm², the hardness of welded seam reaches the highest value of 68.88 HV. Under the appropriate magnetic field parameters and active agent ratio, the arc stiffness is the largest and the arc shrinkage is obvious. At the moment, the grains get obviously refined with the arc stirring effect, and the amount of precipitated Al₁₂Mg₁₇ phase significantly increases, which shows the positive effect in improving the mechanical properties of welded joint.