Effect of Build Plate Heating on Microstructure, Precipitation Behavior, and Fatigue Performance in LPBF-Processed AlMgSc alloy

The thermal history during the Laser Powder Bed Fusion (LPBF) process plays a critical role in determining the final microstructure and mechanical properties of printed components. One key parameter in this context is the build plate temperature, which significantly influences thermal gradients, solidification rates, and resulting residual stresses. A higher thermal gradient, typically observed during LPBF, often leads to the development of anisotropic grain structures, high residual stresses, and potential part distortion. In contrast, heated build plate helps reduce the thermal gradient, thereby alleviating residual stresses and minimizing deformations. Elevated average temperature promotes in-situ heat treatment effects, causing nucleation and growth of Al₃Sc precipitates, and encourages the transformation of a bi-modal grain structure into a more desirable, fully equiaxed grain morphology. In this study, a comparative analysis is carried out to systematically investigate the influence of build plate heating on the microstructure evolution, precipitation behavior, and fatigue properties of LPBF-manufactured AlMgSc alloy. Samples are fabricated under two distinct conditions: with and without build plate heating. The findings demonstrate that build plate heating significantly reduces thermal gradients, thereby lowering residual stresses and improving dimensional stability. The heated build plate also promotes the development of a fully equiaxed grain structure, enhancing mechanical isotropy. Furthermore, earlier and more uniform precipitation of Al₃Sc particles is observed, contributing to higher tensile strength and extended fatigue life. These results provide a valuable framework for optimizing thermal management strategies in LPBF processes and enhancing the performance of aluminum alloy components for demanding structural and aerospace applications.