Efficient distortion predictions of high-performance steel alloy parts fabricated by pragmatic deposition strategies in laser melting deposition

For the prediction of residual distortions of high-performance steel alloy parts induced by laser melting deposition (LMD), two efficient simulation methods are developed, which are the improved thermal-mechanical coupled method and the multiscale method. In the improved thermal-mechanical coupled method, the detailed loading process of the moving laser heat source is omitted, and the deposited coarse blocks are used to divide the LMD parts, which can improve the efficiency of mechanism exploration for the LMD process. Based on the eight-layer line deposition model, the length range of the deposited coarse blocks that can improve the computational efficiency under the premise of accuracy is explored, which is 5–8 mm. The distortion of the substrate after printing two-layer multipath part by pragmatic deposition strategies is accurately predicted by this method, which is consistent with the experimental measurement. The deviation between the predicted maximum distortion and the actual value is only 0.8%. Furthermore, a multiscale method based on the inherent strain method is also adopted. The two simulation methods are used to predict the distortion of the substrate after depositing pragmatic square frame structure. The deviations of the maximum distortion predicted by the improved thermal-mechanical coupled method and the multiscale method are 5.2% and 4.3%, respectively. The time-consuming of the multiscale method is only 2.8% of the former. For the direct prediction of distortion results of large-sized LMD parts in engineering, the advantages of the multiscale method are significant.