A crack-free and high-strength Al-Cu-Mg-Mn-Zr alloy fabricated by laser powder bed fusion

Abstract

Laser Powder Bed Fusion (LPBF) is considered as one of the most current additive manufacturing technologies that could prepare customized and complex parts. There have been challenges for LPBF-fabricating 2xxx (Al–Cu) alloy because that own alloy elements cause large solidification ranges and hot cracking is susceptible to generate during solidification. In this study, a crack-free and high-strength Al–Cu–Mg–Mn–Zr alloy was designed and manufactured by LPBF. The results showed that the laser energy density has an important effect on microstructure and density, and it was sufficient to melt the alloy powder and deliver high-quality builds at 333 J/mm3. The microhardness, tensile strength, and yield strength of the LPBF-fabricated Al–Cu–Mg–Mn–Zr alloy increased with increasing laser energy density. In addition, the tensile fracture surfaces exhibited mixed brittle and ductile fracture features at low energy density values (231–358J/mm3). The ductile fracture was observed at higher energy density values (>463J/mm3). When the laser density was set at 500 J/mm3, the LPBF-fabricated alloy exhibited high relative density (99.88%) and the most optimal mechanical properties, with microhardness of 141.5 Hv, tensile strength of 343.9 MPa, yield strength of 311.0 MPa, and elongation of 6.1%. After solution treatment at 560 °C for 2 h and water quenching, the Al–Cu–Mg–Mn–Zr alloy exhibits the excellent mechanical properties with ultimate tensile strength of 483.6 MPa, yield strength of 365.5 MPa, and elongation of 13.4%.