Ceramic insert enabled build plate thermal isolation for enhanced microstructure and residual stress mitigation in laser-based powder bed fusion of metals

Mitigating thermally induced residual stresses remains a critical challenge in components made by laser-based powder bed fusion of metals (PBF-LB/M). This study proposes a novel passive thermal isolation strategy utilizing a ceramic base plate to control thermal gradients during fabrication, which in turn reduces residual stress and simultaneously inducing distinct microstructural differences in PBF-LB/M processed stainless steel 316 L alloys. A combined approach using finite element method (FEM) simulations, neutron diffraction, microstructure analysis, and mechanical testing, was employed to systematically evaluate the thermal, structural, and mechanical responses. The ceramic base plate elevates the temperatures of the part during fabrication while reducing thermal gradients, and effect that corresponded with neutron diffraction measurements showing reduced tensile and compressive residual stresses across the build. Importantly, distinct microstructure differences were identified, characterized by grain coarsening, reduced local misorientation, a lower twin fractions, and diminished defects. Collectively, these features promoted greater microstructural uniformity and effectively suppressed thermal induced plasticity. The enhanced microstructural homogeneity across different locations also contributed to more uniform mechanical properties throughout the specimen. Unlike conventional strategies requiring additional energy input or system modifications, the proposed approach offers a scalable, energy-efficient, and easily implementable solution that does not interfere with existing machine control systems. It can be integrated with other stress-relief methods such as preheating, and/or other active systems to provide synergistic effects. Moreover, the reduced thermal deformation enhances dimensional accuracy and manufacturing reliability, without compromising mechanical performance, addressing critical requirements in aerospace, biomedical, and energy applications.