Effect of Heat Treatment on SS316L Manufactured by L-PBF with High VED

Abstract

This work evaluates the impact of heat treatment on SS316L manu-factured by laser powder bed fusion (L-PBF) under high volumetric energy density (VED ≈ 467 J/mm³) and low layer thickness. The as-built sample exhib-ited fine cellular/columnar microstructures with clear melt-pool boundaries, which remained largely unchanged after heat treatment at 650 °C but fully dis-solved and transformed into coarse equiaxed grains after solution treatment at 1120 °C. Density increased from 94.91% (AB) to 96.03% (HT-650) and 99.45% (HT-1120). XRD confirmed fully austenitic phases in the AB and HT-650 samples, while the HT-1120 sample showed peak redistribution and the ap-pearance of a ferrite (110) peak. Hardness remained nearly unchanged after the 650 °C treatment but decreased following the 1120 °C treatment due to grain coarsening. Overall, low-temperature heat treatment preserved the original mi-crostructure with minimal property changes, whereas high-temperature treat-ment promoted phase transitions, grain growth, reduced hardness, and improved densification.