Role of cell structure in early-stage strengthening of L-PBF stainless steel 316L

This study investigates the influence of cell structure on the early-stage strengthening of stainless steel 316L produced by laser powder bed fusion. Two sets of samples were prepared: one as-printed, exhibiting a typical cell structure inside grains, and one subjected to a heat treatment, thus with cell-free grains. Tensile tests show about 150 MPa higher strength in the as-printed condition, corresponding to a 37% improvement as compared to the cell-free state. An analysis based on crystal plasticity simulations indicates that this corresponds to an increase in the critical resolved shear stress on the slip systems of 54 MPa. This value is consistent with the strengthening induced by the cell structure predicted by a simple dislocation forest hardening model, highlighting the significant effect of the cell structure on mechanical strength.