Part scale estimation of residual stress development in laser powder bed fusion additive manufacturing of Inconel 718

Abstract

Residual stress has been among the primary problems in the laser powder bed fusion (LPBF) additive manufacturing. Nevertheless, complex physics and multi-scale nature of the problem make an accurate prediction of residual stress at the part level a great challenge. Thus, the present study developed the finite element framework to predict the part scale residual stress development in the LPBF of Inconel 718. Two-scale models were used coherently. A mesoscale model calculated the stress formation in a deposited powder layer by considering the influence of process conditions and scan strategies. Subsequently, the inherent strain approach was used for the part level prediction. The inherent strain values were estimated according to numerical results from the mesoscale model. Numerical validation was made by comparing the transient development of residual stress with reported measurements from the neutron diffraction of over 200 data points. The proposed framework provided the prediction which matched excellently with experimental results. Ultimately, the present study established the proven framework which could be used for further investigation on part scale-related issues in the LPBF process.