Enhancing the properties of 2219 aluminum alloy deposited by resistance seam additive manufacturing through rolling and heat treatment: Microstructure evolution and strengthening mechanism

Abstract

Resistance seam additive manufacturing (RSAM) is a novel technology that deposits metal powder layer by layer through pressure and resistance heat to achieve bulk materials. In this study, 2219 aluminum alloy blocks were prepared using this technology, and subsequently subjected to rolling treatment and solution and aging (T6) heat treatment. The results indicated that, the rolling treatment reduced the porosity, increased the dislocation density of the sample, and enhanced the solid solubility of Cu element in the matrix. T6 heat treatment caused the dissolution of the α+θ eutectic into the matrix and then θ phase and θ′ phase were re-precipitated. Especially after the Rolling + T6 hybrid process, a uniform distribution of nanoscale needle-like θ′ phases was precipitated in the sample. The fine and densely dispersed θ′ phases not only effectively pinned dislocations but also cooperated with the matrix deformation, and under their precipitation strengthening effect, the material achieved excellent mechanical properties, with yield strength, ultimate tensile strength, and elongation increasing from 105 MPa, 126.4 MPa, and 6.9 % to 334.6 MPa, 506.6 MPa, and 16.1 %, respectively. This study provides a new pathway for the additive manufacturing of high-strength aluminum alloys.