The effect of build orientations on mechanical and thermal properties on CuCrZr alloys fabricated by laser powder bed fusion

Abstract

Laser powder bed fusion (LPBF) is a kind of popular additive manufacturing process to fabricate sophisticated components in recent years. However, it is still challenging to fabricate copper alloys due to excellent thermal properties and high reflective to laser beams during LPBF process. As such, green laser beam has been employed in present work to fabricate copper-chromium-zirconium (CuCrZr) alloys in present work. To enhance performance, post-heat-treatment was employed on the alloys. The mechanical properties in present work are superior to most of LPBF-built CuCrZr alloys using conventional infrared laser. So far, most of studies about additive manufactured (AM-ed) CuCrZr alloys only focus properties of alloys perpendicular to build directions. Hence, the mechanical properties and thermal properties of LPBF-built alloys along different build orientations were investigated. The slender columnar grains were observed. Nevertheless, heat-treated samples along transverse directions own better mechanical properties (yield strength (YS): 505 MPa, ultimate tensile strength (UTS): 585 MPa, Elongation (EL): 14.4%) and better thermal properties (307 W/mK). While the heat-treated samples along build directions own lower strength (YS: 472 MPa, UTS: 495 MPa) with better ductility (EL: 17.8%) and poor thermal conductivity (255 W/mK). The mechanical and thermal anisotropy attributes the stronger {110} grain orientation and lower fraction of low angle grain boundaries (LAGBs) along build directions due to the columnar structure with fine equiaxed grains.