Microstructure and Mechanical Properties of Tungsten Inert Gas Weld Joints of Sprayed and Cast Aluminium–Lithium Alloy

Abstract

The weld joints of sprayed 2195-T6 and cast 2195-T8 aluminium–lithium alloy were created using tungsten inert gas with filler wire. The microstructures and mechanical properties of the weld joints were examined. The results of the microstructure analysis showed that the width of the equiaxed grain zone (EQZ) and the amount of the second phase θ’(Al2Cu) was greater in the weld joint of the cast 2195-T8 Al–Li alloy than that of the sprayed 2195-T6 Al–Li alloy. Tensile testing indicated that failures occurred in the EQZ and partially melted zone (PMZ) for both weld joints. The tensile strength and elongation of the weld joints of the sprayed 2195-T6 and cast 2195-T8 Al–Li alloys were about 68.2%, 89.7%, and 50.7% and 28.3% those of the base metal in the joint, respectively. The cast 2195-T8 Al–Li alloy joint had more pores and cracks, resulting in lower tensile strength and elongation than those in the sprayed alloy. Further, the tensile fracture surface morphology indicated that the fracture mode of the sprayed 2195-T6 Al–Li alloy was a mixed fracture mode dominated by plastic fracture and that of the cast 2195-T8 Al–Li alloy joints was a mixed fracture mode dominated by brittle fracture.