Experimental and numerical investigation of residual stress evolution under heat treatment in L-PBF 316L steel

Residual stress critically affects the performance and reliability of laser powder bed fusion (L-PBF) 316L stainless steel. While heat treatment (HT) is essential, existing constitutive models often fail to capture relaxation under variable temperature conditions and are limited to narrow ranges. This work quantifies the effects of HT temperature (650–900 °C), holding time and heating rate using X-ray diffraction and numerical simulations. Stress reduction is governed mainly by temperature; at 900 °C for 1 h, stresses fall below 50 MPa (>90% relief), while the influence of holding time diminishes at higher temperatures. A validated 650–900 °C model captures coupled temperature–time–rate effects and shows most stress is relieved during heating rather than soaking, enabling HT schedule optimization.