Effect of artificial ageing on microstructures and mechanical properties of selective laser melted AlMg4.5Sc0.55Mn0.5Zr0.2 alloy

Abstract

AlMg4.5Sc0.55Mn0.5Zr0.2 alloys were fabricated by selective laser melting.The effects of artificial ageing parameters on Vickers hardness of the alloy were investigated. The room temperature tensile properties and microstructures of as-built and optimized artificial ageing treated alloys were analyzed. Results indicate that the Vickers hardness of the alloy increases from 102HV to more than 140HV by artificial ageing treatment. As the rising of ageing temperature, ranging from 305℃ to 335℃, or prolongation of the ageing duration, from 1.5 h to 48 h, Vickers hardness presents increasing first, then decreasing and finally trends to be stable. The room temperature tensile properties of the alloys aged at 315℃ for 3 h or 12 h are almost equal, and there is no obvious anisotropy. The ultimate tensile strength and yield strength reach 470 MPa and 410 MPa respectively, with elongation of about 15.0%.The improvement of mechanical properties is due to the dispersion precipitation of nano-reinforced particles Al3(Sc, Zr), which possess a coherent interface with the matrix during artificial ageing.

Keywords

• selective laser melting
• almg4.5sc0.55mn0.5zr0.2 alloy
• artificial ageing
• microstructure
• mechanical property