Predictive modeling of solidification during laser additive manufacturing of nickel superalloys: recent developments, future directions

Abstract

Additive manufacturing (AM) processes produce parts with improved physical,\nchemical, and mechanical properties compared to conventional manufacturing\nprocesses. In AM processes, intricate part geometries are produced from\nmulticomponent alloy powder, in a layer-by-layer fashion with multipass laser\nmelting, solidification, and solid-state phase transformations, in a shorter\nmanufacturing time, with minimal surface finishing, and at a reasonable cost.\nHowever, there is an increasing need for post-processing of the manufactured\nparts via, for example, stress relieving heat treatment and hot isostatic\npressing to achieve homogeneous microstructure and properties at all times.\nSolidification in an AM process controls the size, shape, and distribution of\nthe grains, the growth morphology, the elemental segregation and precipitation,\nthe subsequent solid-state phase changes, and ultimately the material\nproperties. The critical issues in this process are linked with multiphysics\n(such as fluid flow and diffusion of heat and mass) and multiscale (lengths,\ntimes and temperature ranges) challenges that arise due to localized rapid\nheating and cooling during AM processing. The alloy\nchemistry-process-microstructure-property-performance correlation in this\nprocess will be increasingly better understood through multiscale modeling and\nsimulation.\n