Microstructural evolution and its effect on mechanical properties of spray deposited 2195 alloy during porthole die extrusion process

Abstract

The extrusion process of spray deposited 2195 Al–Cu–Li alloy was carried out with a porthole die. The microstructural evolution in the extrusion, especially the welding process in the near-vacuum chamber was characterized. The effect of weld seam on the microstructures and properties of profiles was revealed. It was found that the materials close to bridge is refined obviously and forms a layer of fine grain, while a typical fibrous structure with incomplete recrystallized grains is formed in matrix area. The fine grain layer forms welding area. The welding area mainly contains shear type texture while matrix area mainly has rolling type texture during the welding process. The sufficient recrystallization in the welding area results in the low dislocation density and weakens the work-hardening effect, which further suppresses the precipitation of the strengthening phase Al2CuLi. The massive dislocations of matrix area promote the precipitation of Al2CuLi, which improves the hardness of matrix area. The “kissing-bond” micro-pores on the welding interface and the massive dense and fine secondary particles in the welding area reduce the tensile properties of the profile with weld seam.