Effective Platform Heating for Laser Powder Bed Fusion of an Al-Mn-Sc-Based Alloy

Platform heating is one of the effective strategies used in laser powder bed fusion (LPBF) to
avoid cracking during manufacturing, especially when building relatively large-size components,
as it removes significant process-induced residual strains. In this work, we propose a novel and
simple method to spare the elaborate post-processing heat treatment typically needed for LPBF Al-Sc
alloys without compromising the mechanical properties. We systematically investigated the effects
of LPBF platform heating at 200 ◦C on the residual stress relief, microstructure, and mechanical
performance of a high-strength Al-Mn-Sc alloy. The results reveal that LPBF platform heating at
200 ◦C is sufficient to largely relieve the process-induced residual stresses compared to parts built on
an unheated 35 ◦C platform. Meanwhile, the platform heating triggered the dynamic precipitation
of uniformly dispersed (1.5–2 nm) Sc-rich nano-clusters. Their formation in a high number density
(1.75 × 1024 m−3) resulted in a ~20% improvement in tensile yield strength (522 MPa) compared to
the build on the unheated platform, without sacrificing the ductility (up to 18%). ... mehrThe improved
mechanical properties imply that platform heating at 200 ◦C can strengthen the LPBF-synthesised
Sc-containing Al alloys via in situ aging, which is further justified by an in situ measurement study
revealing that the developing temperatures in the LPBF part are within the aging temperature range
of Al-Sc alloys. Without any post-LPBF treatments, these mechanical properties have proven better
than those of most Al-Sc alloys through long-time post-LPBF heat treatment.