Influence of process parameters in powder bed fusion of 316L steel: a residual stress study

To maintain the structural integrity in additively manufactured samples, it is important to study the induced residual stresses which are widely ignored. Powder bed fusion (PBF) is a type of additive manufacturing process in which the metal powder is added to a substrate, step by step. Scanning parameters including layer thickness, overlap percentage, the angle between layers and scanning strategy that can be controlled in this process lead to different mechanical properties, microstructures, and residual stresses. This study compares the effects of layer thickness, overlap percentage, and the angle between layers on residual stresses. For this purpose, several specimens with different process parameters were made from 316L steel powder, using PBF, and the residual stresses were measured by incremental centre hole drilling method. Furthermore, residual stresses induced in powder bed fusion technique were also assessed numerically. It was observed that the overlap percentage showed more impact among other parameters. It was also addressed that manufacturing parameters should be carefully selected to minimize the magnitude of residual stresses as they can affect the residual stresses field simultaneously. Experimental and finite element results showed a good agreement.