ZL109铝硅合金CO_2激光焊接头组织与性能

Microstructure and mechanical properties of CO_2 laser-welded joint of ZL109 aluminum silicon alloy

采用CO2激光器在无填充金属的条件下对ZL109铝硅合金进行焊接,研究了焊接接头的微观组织与力学性能.结果表明,焊缝组织由胞状枝晶和树枝晶组成,焊缝物相主要是α-Al,Si和Mg2Si.焊缝显微硬度高于热影响区和母材,当焊接速度为3.0m/min,其平均值为125HV0.05.热输入对接头力学性能有显著的影响,随着热输入的增大,接头抗拉强度和断后伸长率均先增加后降低,当热输入为44J/mm时,接头抗拉强度和断后伸长率值最高(121.2MPa,4.3%),断裂发生在热影响区,断口表面具有脆性断裂特征.

Laser beam welding of ZL109 aluminum silicon alloy was carried out by CO2 laser without any filler,and microstructure and mechanical properties of the joints were investigated. The results show that weld microstructure consists of cellular-dendrite and dendrite crystals,and its phase composition contains α-Al,Si and Mg2Si phases. The microhardness of weld is higher than that of both heat-affected zone and base metal,its average microhardness being 125 HV0.05 with the welding speed of 3.0 m/min. The heat input has a significant influence on mechanical properties of the joints. With the increase of heat input,both tensile strength and elongation of the joints increase firstly and then decrease gradually,the maximum tensile strength and elongation (121.2 MPa and 4.3%) being achieved at the heat input of 44 J/mm. The joint fracture occurs in heat-affected zone,and the fracture surface exhibits brittle fracture features.