Mechanical Behavior and Microstructural Evolution in 316L Stainless Steel Processed by Laser Powder bed Fusion under Different Annealing Conditions

This study investigates the influence of annealing temperature on the microstructure and mechanical properties of 316L stainless steel manufactured using laser powder bed fusion technology. Higher annealing temperatures reduced porosity in both horizontally and vertically printed samples. Horizontal samples exhibited vertically aligned melting pools, while vertical samples showed scale-like pool structures. Annealing at 950°C dissolved melting pool boundaries and created continuous grain structures, with vertical samples demonstrating faster grain growth. Horizontal samples showed higher initial hardness, but lower ductility than vertical samples. The annealing process improved elongation in all samples, while microstructural analysis revealed that horizontal samples had extensive twinning and dislocation activity.