Optimizing solidification dendrites and process parameters for laser powder bed fusion additive manufacturing of GH3536 superalloy by finite volume and phase-field method

Abstract

Investigating the surface morphology and microstructure of laser powder bed fusion (L-PBF) in solidification and optimizing process parameters is crucial for improving the accuracy and performance of cladding parts of GH3536 superalloy. In this study, a computational model incorporating Computational Fluid Dynamics (CFD) and Discrete Element Method (DEM) was utilized to simulate the mesoscale evolution of the molten pool in L-PBF for GH3536 superalloy. Furthermore, the growth of columnar dendrites along the fusion boundary under transient conditions was simulated utilizing a quantitative phase-field model. The impact of scanning speed and laser power on temperature distribution, molten pool size, surface morphology of cladding layer, and columnar dendrite spacing during solidification of single-track L-PBF were examined. The findings suggest that the molten pool undergoes a fast process characterized by significant temperature gradients. Increasing the laser power or reducing the scanning speed results in higher maximum molten pool temperature, as well as increased molten pool depth and width. Overlarge or undersized scanning speed and laser power can result in poor surface quality of the cladding layer. When the laser power was 120 W and the scan speed was 0.4 m/s, the cladding layer exhibited improved surface morphology, with finer columnar dendrites observed at the molten pool's base. This study delved into understanding the evolution characteristics of the molten pool and the growth process of columnar dendrites at the molten pool's base, providing valuable insights for determining appropriate experimental process parameters for L-PBF of GH3536 superalloy.