5059铝镁合金TIG焊接接头组织性能研究

Study on Microftructure and Properties of 5059 Al-Mg Alloy TIG Welded Joint

通过开展5059铝镁合金4 mm自动TIG焊对比试验,当热输入为13.8 kJ/cm时,焊缝组织为尺寸较大的等轴晶组织,晶内呈树支状生长,平均晶粒度约为2.56级,焊缝区域能谱(EDS)发现第二相含有7.78%Mg、9.20%Mn,接头的抗拉强度低于330 MPa。当降低热输入为12.5 kJ/cm时,通过调整焊接压力架工装的工作状态,保证焊接试板有效压紧,提高焊缝冷却速度,焊缝组织为尺寸较小的等轴晶组织,呈条状规则排列,平均晶粒度约为4.91级,焊缝区域能谱(EDS)发现第二相含有11.10%Mg、8.86%Mn,接头中形成含有Mg、Mn的金属化合物强化相,弥散地分布在铝基体中,且Mg、Mn元素含量较高,焊缝区显微硬度可达到基材显微硬度的90%以上,接头的抗拉强度满足规定值(大于330 MPa)。

Through the comparison test of 5059 Al-Mg alloy 4 mm automatic TIG welding,it is concluded that when the heat input is 13.8 kJ/cm,the weld microstructure is a large equiaxed crystal structure with dendritic growth within the crystal,and the average grain size is about 2.56.The second phase contains 7.78%Mg and 9.20%Mn,according to the energy spectrum(EDS)in the weld zone.The tensile strength of the joint is less than 330 MPa.When the heat input is reduced to 12.5 kJ/cm,by adjusting the working state of the welding pressure frame tool,the welding test plate can be effectively pressed and the weld cooling rate can be improved.The weld microstructure is small equiaxed crystal structure,which is arranged in a regular strip,and the average grain size is about 4.91.It was found that the second phase contained 11.10%Mg and 8.86%Mn,and the joint formed a metal compound strengthening phase containing Mg and Mn,dispersed in the aluminum matrix,and the content of Mg and Mn was high.The microhardness of the weld zone could reach more than 90%of the microhardness of the substrate,and the tensile strength of the joint could meet 330 MPa.