A mechanism for the microstructure formation in welds of laser welded aluminium-lithium alloy 2A97

As the third-generation aluminum-lithium alloy developed by China, 2A97 is widely used in the aerospace field. However, the weak fine equiaxed zone (FEQZ) of weld severely limits its application. In this study, the macro- and microscopic characteristics of weld and the formation mechanism of the microstructure were investigated under the condition of large heat input non-autogenous laser welding (NLW) with ER2319 and ER4047 filler metals. The results showed that, the porosity imperfection in 2A97-T3 via NLW could be modified by using ER2319. The addition of Zr in the equiaxed zone resulted in effective refinement of equiaxed dendrites. The distribution of FEQZ concentrated at the four corners of the weld which was affected by the flow of weld pool. Furthermore, the morphology and distribution of FEQZ were influenced significantly by welding parameters and filler metals.

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