新型铝合金MIG焊接头微观组织与力学性能  

Microstructure and mechanical properties of new aluminum alloy MIG welded joint

作　　者：金聪聪 黄立兵 黄文彬 王大力 马月婷 李鹏[1] 董红刚[1] JIN Congcong;HUANG Libing;HUANG Wenbin;WANG Dali;MA Yueting;LI Peng;DONG Honggang(School of Materials Science and Engineering,Dalian University of Technology,Dalian,116024,China;The 4th Military Representative Office of the Air Force Armament Department in Shenyang,Shenyang,110023,China)

机构地区：[1]大连理工大学,材料科学与工程学院,大连116024 [2]空军装备部驻沈阳地区第四军事代表室,沈阳110023

出　　处：《焊接学报》2024年第7期74-82,共9页Transactions of The China Welding Institution

摘　　要：随着船舶轻量化和快速化的发展,以铝代钢成为未来船舶制造的必然趋势.对一种10 mm厚新型铝合金进行单面MIG焊工艺试验,研究两层三道焊和三层四道焊对接头综合性能的影响规律.结果表明,焊缝上表面和下表面宏观形貌均较好,都有α-Al、Al6(Fe,Mn)和Mg2Si相;在靠近熔合线的热影响区中有尺寸较大的等轴晶生成,焊缝边缘沿垂直于熔合线方向生成柱状晶,焊缝中心为树枝晶,且每层焊缝晶粒尺寸不同,前层焊缝晶粒尺寸小于后层焊缝晶粒尺寸;Fe和Mn元素在热影响区发生偏聚,形成Al6(Fe,Mn)相,Mg元素倾向于沿焊缝晶界或分布在焊缝组织中以平衡相的形式析出.1号接头平均抗拉强度为294 MPa,达到母材抗拉强度的78.4%,断后伸长率为6.56%,2号接头平均抗拉强度为350 MPa,达到母材抗拉强度的93.3%,断后伸长率为12.3%;接头硬度整体表现为焊缝区最低,热影响区次之,母材最高,同时多层多道焊的每层焊缝硬度与焊接顺序有关,第一层焊缝硬度最大.With the development of light weight and fast speed of ships,replacing steel with aluminum has become an inevitable trend of future shipbuilding.A new 10 mm thick aluminum alloy was tested by single-side MIG welding technology,and the effects of two layers and three-pass welding/three layers and four-pass welding on the comprehensive properties of the joint were studied.The results show that the surface and bottom surface of the weld seams have better macroscopic morphology and there areα-Al,Al6(Fe,Mn)and Mg2Si phase.In the heat-affected zone near the fusion line,large equiaxed crystals are formed,and columnar crystals are formed along the direction perpendicular to the fusion line at the edge of the weld.The center of the weld zone is characterized by dendrites,and the grain size of each layer is different,the grain size of the front layer is smaller than that of the back layer.The Fe and Mn elements are segregated in the heat affected zone to form the Al6(Fe,Mn)phase,and Mg tends to precipitate along the weld grain boundary or distributed in the weld microstructure in the form a balanced phase.The average tensile strength of No.1 joint is 294 MPa,reaching 78.4%of the tensile strength of the base material,its elongation is 6.56%;the average tensile strength of No.2 joint is 350 MPa,reaching 93.3%of the tensile strength of the base material,its elongation is 12.3%.The weld zone has the lowest hardness for the joint overall performance,followed by the heat affected zone and the highest in the base metal.For multilayer and multipass welding,the hardness of each layer is related to the welding sequence,and the hardness of the first layer is the highest.

关 键 词：熔化极气体保护焊 多层多道焊 韧性断裂 硬度 

分 类 号：TG442[金属学及工艺—焊接]