Effect of micro morphology in different zones on mechanical properties of 2060 Al-Li alloy laser welded joints

Abstract

Al-Li alloys have been applied in modern aerospace manufacturing fields due to their excellent properties. In this investigation, 2-mm-thick 2060 Al-Li alloy laser beam welding was carried out under different heat input by KUKA Robot. The macro profile and micro morphology characteristics of weld seam cross section were observed. For further investigating the effect of micro morphology in different zones on mechanical properties of welded joints, micro-hardness test and tensile test were carried out and the experimental results were analyzed. It was found that the micro-hardness distribution was corresponding to the grain morphology distribution. The average value of micro hardness in the weld seam center was the smallest because of the biggest grain size. During the tensile test process, there was no obvious necking phenomenon observed in the fracture section and the displacement of tensile specimen was extremely small. According to the analysis of fracture morphology, the bigger and deeper dimple in fracture contributed to better tensile performance. Besides, the strengthening phases were rich in Cu element that was considered as the result of elements redistribution during laser beam welding process.