Al-Cu-Li合金电子束填丝焊接头显微组织与力学性能

Microstructure and mechanical property of Al-Cu-Li alloy joint formed by electron beam welding with filler wire

采用ER4043焊丝作为填充材料,对厚度为2 mm的Al-Cu-Li合金进行电子束填丝焊,分析测试接头的显微组织与力学性能。在电子束焊过程中,Al-Si焊丝的添加可明显改善焊缝成形和接头质量。微观分析显示,接头焊缝区沿熔合线分布细小的等轴晶,熔合区主要由α(Al)基体相及T_(1)(Al_(2)CuLi),θ′(Al_(2)Cu),T(AlLiSi),β′(Al_(3)Zr),δ′(Al_(3)Li)等强化相组成。焊接时添加电子束扫描可细化焊缝晶粒,有利于提高接头的力学性能。力学性能测试表明,与母材相比,接头熔合区的显微硬度有所降低;焊接时添加方形波电子束扫描,获得接头的抗拉强度为374.7 MPa,达到母材抗拉强度的74.7%。接头拉伸断口表面分布有许多尺寸较大的等轴韧窝,呈韧-脆混合型断裂特征。

The ER4043 welding wire was used as filler metal,and the Al-Cu-Li alloy with the thickness of 2 mm was welded by electron beam welding with filler wire.The microstructure and mechanical property of welded joint were analyzed and measured.During the electron beam welding process,by the addition of Al-Si welding wire,the weld formation and joint quality were significantly improved.The microstructure analyses showed that there were fine equiaxed grains distributed along the bond line,and the fusion zone(FZ)of joint was mainly composed of α-Al matrix phase and some strengthening phases such as T_(1)(Al_(2)CuLi),θ′(Al_(2)Cu),T(AlLiSi),β′(Al_(3)Zr)andδ′(Al 3Li).During welding,the grains in weldment could be refined by the addition of electron beam scanning,which was advantageous to the mechanical property of welded joint.The mechanical property test showed that,compared with the base metal(BM),the microhardness in FZ was decreased to a certain extent.By the addition of square wave electron beam scanning during welding,the tensile strength of welded joint was 374.7 MPa,which was 74.7%of that of the base metal.There were many larger equiaxed dimples distributed on the tensile fracture surface of joint,which was characterized by the mixed mode of ductile-brittle fracture.