铝合金激光-TIG复合焊热输入对组织及性能的影响

Effect of heat input on microstructure and properties of aluminum alloy with laser-TIG hybrid welding

研究了激光-TIG复合焊在不同热输入下焊缝成形、接头拉伸性能、断口特征、接头硬度特征及接头金相特征。试验结果表明,在文中试验条件下:+7 mm离焦量的热输入是+5 mm离焦量的1.6倍,大热输入下,焊缝变得宽大;+7 mm离焦量下焊缝背面宽度是+5 mm离焦量的1.2倍,接头拉伸性能下降,+5 mm离焦量和+7 mm离焦量下抗拉强度分别为母材的88%和82%,断后伸长率分别为母材的96%和48%;大热输入下,断口处韧窝较为平浅,显微硬度降低;热输入较小时,无论是焊缝还是熔合区,第二相析出质点数量多而细小而且呈弥散分布;热输入较大时,焊缝及熔合区的第二相质点数量较少且尺寸较大,即焊缝及熔合区的第二相质点聚集长大。

Weld forming,tensile properties,fracture characteristics,hardness characteristics and microstructure characteristics of joints were studied under different heat inputs by laser-arc hybrid welding.The results showed that,under conditions of the experiment,the heat input of+7 mm defocus was 1.6 times as much as that of+5 mm defocus,and welds became wide under high heat input.The back width of welds under+7 mm defocus was 1.2 times that of welds under+5 mm defocus.Tensile properties of joints decreased,tensile strength of+5 mm defocus and+7 mm defocus was 88%and 82%of the base metal respectively,and elongation after fracture was 96%and 48%of the base metal respectively.Under high heat input,dimples at the fracture were relatively shallow and microhardness decreased.Precipitated particles in weld and fusion zone were more,fine and dispersed under lower heat input,while they were less and coarse under higher heat input,namely they gathered and grew up.