Influence of thermal effects via powder bed fusion on the graded microstructure and mechanical properties of near- beta Ti-5Al-5Mo-5V-3Cr-1Zr alloy

Powder bed fusion (PBF) is a well-established method in the additive manufacturing (AM) industry. Despite its popularity, effectively managing the microstructure and mechanical properties of PBF-produced components remains a significant engineering challenge. This study aims to address this challenge by investigating the thermal accumulation effect of PBF substrate preheating on sample microstructure. The study demonstrates the graded microstructure resulting from "in-situ aging" at 630 degrees C at different deposition heights. The results reveal how heat accumulation and cooling rate contribute to the varying alpha(p) lamellae content and a phase selection across different regions. Notably, the bottom region, with an ap lamellae content of 53.5% and a beta r content of 46.5%, exhibits the highest of fracture toughness value of 87.5 MPa.m(1/2). The mechanical properties exhibit a clear grade distribution with increasing deposition height. In-situ manipulation of microstructure and mechanical properties provides theoretical and engineering guidance for future AM strategies.