6082铝合金中厚板高频脉冲MIG对接焊接头的组织和性能分析

Microstructure and Properties of High Frequency Pulse MIG Butt Joint for 6082 Aluminum Alloy Plate

采用高频脉冲MIG焊进行6082-T6铝合金15 mm中厚板对接焊,研究接头成形、微观组织和力学性能。接头条件为:坡口角度40°,焊接间隙1 mm,钝边0.5 mm,3层3道。结果表明:与常规脉冲MIG焊(深熔焊模式)相比,在相同的接头条件、焊接热输入降低约11%的状况下(常规脉冲MIG焊热输入为17.12 kJ/cm,高频脉冲MIG焊热输入为15.21 kJ/cm),高频脉冲MIG深熔焊的根部熔深增加约14%,两种焊接方法接头的组织类型相同,均为α-Al基体+化合物析出相,但常规脉冲MIG焊接头过热区的晶粒明显较为粗大;拉伸试样均断在热影响区处,断口呈典型的韧性断裂形貌,高频脉冲MIG接头的强度系数约为79%,较常规脉冲MIG焊接头的高出约4%;侧弯试样弯曲180°后,受拉面均无裂纹,焊接接头的塑性及熔合良好。对于6082-T6铝合金15 mm板厚的对接接头,高频脉冲MIG焊的焊接成形及接头的组织和性能优于常规脉冲MIG焊。

In this paper,the appearance of weld,microstructure and mechanical properties of the butt joint 6082-T6 alumi‐num alloy(medium plate thickness is 15 mm)were investigated by high-frequency pulse MIG deep penetration welding(welding heat input E=15.21 kJ/cm).The joint conditions:groove angle 40°,welding gap 1mm,thickness of root face 0.5 mm,3 layers and 3 runs.The research results showed that compared with conventional pulse MIG welding(deep penetration welding mode),under the same joint conditions,less welding heat input(for the conventional pulse MIG,E=17.12 kJ/cm,high-frequency pulse MIG deep penetration welding,E=15.21 kJ/cm,decreased by about 11%),the root penetration of highfrequency pulse MIG deep penetration welding is increased about 14%.The microstructure types of the joints of the two welding methods were the same,both of which areα-Al matrix+compound precipitated phase,but the grain size in over‐heated zone of conventional pulse MIG welding was significantly coarser;The tensile specimens were all fractured in the heat affected zone,with typical ductile fracture morphology.The strength coefficient of high-frequency pulse MIG joints is about 79%,which was about 4%higher than that of conventional pulse MIG welded joints;After the side bending samples were bent 180°,the tensile surface of SBB samples were all free of cracks,it showed that the plasticity of the welded joint is better,also the fusion of the welded joint.For the butt joint of 6082-T6 aluminum alloy medium plate(thickness 15mm),the appearance of weld,microstructure and properties of high-frequency pulse MIG welding were superior to conventional pulse MIG welding.