AZ31镁合金与纯Cu超声波点焊接头组织与力学性能研究

Study on Microstructure and Mechanical Properties of Ultrasonic Spot Welded Joint between AZ31 Magnesium Alloy and Pure Cu

采用超声波点焊实现了AZ31镁合金与纯Cu的连接,并借助扫描电镜、能谱仪和拉剪试验对点焊接头的界面显微组织和力学性能进行了研究。结果表明,接头界面组织主要由Mg和Mg2Cu共晶组成。随着焊接输入能的增加,共晶组织的数量不断增多。接头强度先随着焊接输入能的增加而增大,焊接输入能为1500 J时达到峰值,进一步提高焊接输入能导致接头强度下降。在拉剪载荷作用下,焊接输入能为1500 J的点焊试样沿焊点界面发生脆性断裂,裂纹主要沿金属间化合物扩展。

The connection between AZ31 magnesium alloy and pure copper was realized by ultrasonic spot welding. The microstructure and mechanical properties of the spot welded joint were studied by SEM, EDS and tensile-shear test. The results show that the microstructure of the joint interface is mainly composed of Mg and Mg2Cu eutectic. With the increase of welding input energy, the number of eutectic structure increases. The strength of the joint increases with the increase of the input energy, it reaches the peak value when the input energy is 1500 J and the joint strength decrease with the further increase of welding input energy. Under the condition of tensile-shear load, the spot welded specimen under welding input energy of 1500 J occurs brittle fracture along the joint interface, and the cracks mainly extend along the intermetallic compound.