7N01铝合金脉冲MIG焊接头组织与力学性能分析

Analysis of microstructure and mechanical properties of 7N01 aluminum alloy welding joints by pulsed MIG welding

采用脉冲MIG焊接方法分四层焊接12 mm厚7N01铝合金板材,研究了焊接接头的显微组织与力学性能。显微组织结果表明,从盖面层依次到打底层焊道受热循环次数逐渐增加,焊缝组织晶粒越来越粗大,并有明显的交界线;部分熔化区越来越宽,晶粒重熔也逐渐严重。力学性能结果表明,焊缝区硬度明显低于母材硬度,焊接接头的抗拉强度达到312 MPa,断后延伸率9.7%,断裂位置均位于焊缝;焊缝区低温冲击韧性32.5 J/cm2,热影响区低温冲击韧性37.2 J/cm2。试验表明,7N01铝合金采用脉冲MIG焊接方法焊接性能良好。

12 mm thick 7N01 aluminum alloy plates were welded by pulse MIG welding with four layers. Microstructure and mechanical properties of welding joint were studied.Microstructure results showed that from the cosmetic weld to the bottom weld,the thermal cycles gradually increased,and the weld microstructure grain got more and more bulky with obvious boundary;part of the fusion zone was more and more wide,and grain remelting was gradually serious.Mechanical results showed that the hardness of the weld zone was significantly lower than the parent metal＇s;tensile strength of welding joint was 312 MPa,break elongation ratio was 9.7%,fracture location was located in the weld.Low temperature impact toughness of weld zone was 32.5 J/cm2,low temperature impact toughness of heat affected zone was 37.2 J/cm2.Test showed that 7N01 aluminum alloy welding performed well by using pulsed MIG welding methods.