AZ91D变形镁合金激光焊接头的微观组织与机械性能  

Microstructure and Mechanical Properties of Laser Welded AZ91D Wrought Magnesium Alloy

作　　者：丁文兵[1] 童彦刚[1] 邓德安[1] 朱飞 冉洋 

机构地区：[1]重庆大学材料科学与工程学院,重庆400045 [2]重庆市光学机械研究所,重庆401123

出　　处：《中国激光》2014年第2期220-225,共6页Chinese Journal of Lasers

基　　金：国际科技合作计划(2010DFR50010);重庆市国际科技合作计划(2011GZ0051)

摘　　要：对6.3mm厚AZ91D变形镁合金进行CO2激光对接焊试验,激光功率为3500 W,焊接速度为2.5m/min,离焦量为+2mm,氩气流量为10L/min,并采用光学显微镜(OM)、扫描电镜(SEM)和电子万能拉伸试验机考察接头的微观组织、拉伸性能和接头的断口形貌。结果表明:在此工艺参数下,接头焊缝成形良好;焊缝区由细小的α-Mg等轴晶基体组织和沿晶界分布的β-Mg17Al12组成,但存在微观气孔和微裂纹等缺陷;部分熔化区宽度很窄,为5080μm,靠近焊缝区一侧晶粒局部熔化,靠近母材一侧晶粒未熔化;接头抗拉强度(UTS)为232 MPa,延伸率约为6%,分别为母材的90%和25%;接头在焊缝区断裂,断口形貌表明为韧脆混合断裂。AZ91D wrought magnesium alloy plates, with thickness of 6.3 mm, are welded by a CO2 laser beam with a laser power of 3500 W, welding speed of 2.5 m/min, defocusing of ＋ 2 mm and a constant argon gas flow of 10 L/min. The microstructure, tensile properties and fracture morphology of the joint are investigated. The results show that a favorable weld can be obtained. The fusion zone consists of finer α-Mg equiaxed matrix andβ-Mg17 Al12 precipitates distributed along the grain boundaries with pores and microcracks frequently found. The width of the partly melted zone is very narrow, about 50 - 80 /μm, and the grains near the fusion zone are locally melted while those near the base metal are not. Tensile results indicate that the ultimate tensile strength （UTS） and elongation of the joint are respectively 232 MPa and 6 %, about 90 % and 25 % of that of the base metal. The final fracture of the joint occurs at the center of the fusion zone and the fracture morphology shows a combination of brittle and ducile features.

关 键 词：激光技术 材料 变形镁合金 激光焊接 微观组织 机械性能 

分 类 号：TG457.19[金属学及工艺—焊接]