Laser powder bed fusion of high strength aluminum

Abstract

Demands for high strength aluminum alloys processed by Laser Powder Bed Fusion (LPBF) are high and keep rising. However, expensive new alloy compositions or crack formation in existing alloys hinder its wide applicability. It is known from recent work that addition of grain refiners leads to a fine grain structure enabling crack-free, high strength aluminum LPBF parts. In this research, 1 wt% of Zr was added to Al7050. Furthermore, an excess of Zn was provided in the powder material to compensate for Zn losses during LPBF and to maintain the Mg:Zn ratio required for formation of strong and coherent MgZn2 precipitates. After a solution and aging heat treatment, the newly developed alloy has an ultimate tensile strength of 500 MPa and Vickers micro-hardness of 200Hv-0.5kg. Although the elongation at break of the resulting parts is limited, this research shows promising results for future alloy design of affordable high strength aluminum alloys to be processed by LPBF.