7075-T6铝合金双面搅拌摩擦焊接头的组织与性能研究  

Study on microstructure and properties of double-sided friction stir welded joints of 7075-T6 aluminum alloy

作　　者：朱海[1] 王文龙 曾涛 樊稳 晏小龙 ZHU Hai;WANG Wenlong;ZENG Tao;FAN Wen;YAN Xiaolong(College of Mechanical and Electrical Engineering,Northeast Forestry University,Harbin 150040,China)

机构地区：[1]东北林业大学机电工程学院,黑龙江哈尔滨150040

出　　处：《兵器材料科学与工程》2024年第6期125-132,共8页Ordnance Material Science and Engineering

摘　　要：用2.5 mm针长搅拌工具对4 mm厚的7075-T6铝合金轧制薄板进行正、反面各一道次的双面搅拌摩擦焊(DSFSW)试验。研究不同焊接方向对焊接接头的显微组织、硬度、拉伸性能、断裂形貌及弯曲性能的影响。结果表明:焊接接头成形良好,焊核区为均匀细小的等轴晶组织,从焊接接头上表面至下表面焊核区晶粒尺寸先减后增,在焊核重叠区由于受到两次热力-耦合作用,重叠区晶粒较其他NZ更为细小,约为1.5μm。不同焊接方向的接头横截面硬度呈“W”型分布,焊接接头发生软化,硬度最低值出现在热机影响区与热影响区的交界处。因同向焊接接头的焊核区整体晶粒尺寸更细小,使其焊接接头的硬度更优异。拉伸试验中双面搅拌摩擦焊接头抗拉强度最高可达母材的90%。在相同热输入条件下,同向焊接头的抗拉强度明显优于异向焊接头,且断裂方式主要为韧性断裂。在弯曲试验中,双面搅拌摩擦焊接头在面弯与背弯试验时都能承受较大弯曲角度,使焊接接头具备更出色的塑性变形能力。A two-sided friction stir welding(DS-FSW)test was carried out on 7075-T6 aluminum alloy rolled sheet of 4 mm thickness with a 2.5 mm pin length stirring tool.The effects of different welding directions on microstructure,hardness,tensile properties,fracture morphology and bending properties of welded joints were studied.The results show that the welded joint is well formed,and the core zone is uniform and fine equiaaxial crystal structure.The grain size in the core zone decreases first and then increases from the upper surface to the lower surface of the welded joint.In the overlap zone of the welded core,the grain size is smaller than other NZ,about 1.5μm,due to two thermodynamic coupling effects.The cross section hardness of the joint in different welding directions show a"W"shape distribution,the welding joint softened,and the lowest hardness value appeares at the junction of the heat engine affected zone and the heat affected zone.Because the overall grain size of the joint core is smaller,the hardness of the joint is better.In tensile test,the tensile strength of the welded joint can reach 90%of the base material.Under the same heat input conditions,the tensile strength of the welded joint in the same direction is obviously better than that of the welded joint in the opposite direction,and the fracture mode is mainly ductile fracture.In the bending test,the double-sided friction stir welded joint can withstand larger bending angle in the surface bending and back bending test,so that the welded joint has better plastic deformation ability.

关 键 词：7075-T6铝合金 双面搅拌摩擦焊 接头组织 力学性能 

分 类 号：TG44[金属学及工艺—焊接]