6082-T651铝合金板十字接头组织及力学性能

Microstructure and mechanical properties of 6082-T651 aluminum alloy cruciform welded joints

采用熔化极惰性气体保护焊进行了15 mm厚6082-T651铝合金板十字接头焊接。研究了焊接工艺参数对十字接头焊缝成形、拉伸性能和显微硬度的影响,并对接头不同区域的元素分布进行了测试分析。结果表明,随送丝速度和焊接电流增加,焊缝余高逐渐减小,熔深和熔宽逐渐增加;焊缝边缘为柱状晶组织,焊缝中心为枝晶和等轴晶混合组织,晶间液化组织从熔合线一直延伸到热影响区内部;Mg,Si,Fe和Mn等合金元素在焊缝中偏聚形成晶间析出相;十字接头抗拉强度最高达到239 MPa,断裂模式为韧性断裂;接头腹板和翼板侧硬度值呈对称分布,热影响区硬度值随焊接热输入增大而减小,并低于焊缝硬度。

Cruciform welded joints of 15 mm thick 6082-T651 aluminum alloy plates were obtained by metal inert gas welding.The influence of welding parameters on formation of weld,tensile properties and microhardness of cruciform welded joints was studied,and the element distribution in different zones of the joint was analyzed.The results showed that with the increase of wire feeding speed and welding current,the reinforcement of the weld decreased while the penetration and weld width increased.The edge of the weld was a columnar crystal microstructure,and the center of the weld was a mixed microstructure of dendrites and equiaxed crystals.The grain boundary liquation extended from fusion line to the inside of heat-affected zone.Alloy elements such as Mg,Si,Fe and Mn segregated in the weld to form intergranular precipitates.The tensile strength of cruciform welded joints was up to 239 MPa,and the fracture mode was ductile fracture.The microhardness of the joint symmetrically distributed on the web side and the wing side,and the microhardness of the heat-affected zone decreased with the increase of welding heat input,even lower than that of weld zone.