3D Multi-Track and Multi-Layer Epitaxy Grain Growth Simulations of Selective Laser Melting

Abstract

An integrated simulation framework consisting of the 3D finite element method and 3D cellular automaton method is presented for simulating the multi-track and multi-layer selective laser melting (SLM) process. The framework takes account of all the major multi-physics phenomena in the SLM process, including the initial grain structure, the growth kinetics, the laser scanning strategy, the laser–powder and laser–matter interactions, the melt flow, and the powder-to-liquid-to-solid transformations. The feasibility of the proposed framework is demonstrated by simulating the evolution of the epitaxy grain structure of Inconel 718 (IN718) during a 15-layer SLM process performed using a bi-directional 67° rotation scanning strategy and various SLM process parameters. The simulation results are found to be in good agreement with the experimental observations obtained in the present study and in the literature. In particular, a strong (001) texture is observed in the final component, which indicates that the grains with a preferred <001> orientation win the competitive epitaxy grain growth process. In addition, the size and shape of the IN718 grains are governed primarily by the cooling rate, where the cooling rate is determined in turn by the SLM parameters and the build height. Overall, the results show that the proposed framework provides an accurate approach for predicting the final microstructures of SLM components, and therefore, it can play an important role in optimizing the SLM processing parameters in such a way as to produce components with the desired mechanical properties.

Additive Manufacturing of CoCrFeMnNi High‐Entropy Alloy/AISI 316L Stainless Steel Bimetallic Structures

“…Further, columnar grains continue over several layers of the melt pool by epitaxial grain growth due to melting and re‐melting of the pre‐solidified layer of these materials. [ 39 ]…”

“…Further, columnar grains continue over several layers of the melt pool by epitaxial grain growth due to melting and re-melting of the pre-solidified layer of these materials. [39] Furthermore, observation of each grain in additively manufactured AISI 316L stainless steel and CoCrFeMnNi-HEA at higher magnification reveals dendritic cellular and columnar substructures (insets in Figure 3c,e, respectively). Dendritic cellular substructures are common in SLM processed AISI 316L stainless steel samples.…”

Epitaxial Growth and Stray Grain Control toward Single‐Crystal Metallic Materials by Additive Manufacturing: A Review

“…[125] Among them, CA has received increasing attention in the research community for predicting grain structure evolution. [126][127][128][129][130] A 2D CA model is employed in combining with finite-difference method to predict grain structure evolution in SLM process of 316L stainless steel. [131] In both simulation and experimental observations, growing grains tilt about the vertical axis, and serrated GBs are observed.…”

Effect of Scanning Strategy on the Manufacturing Quality and Performance of Printed 316L Stainless Steel Using SLM Process

“…Selective laser melting (SLM) is a widely used additive manufacturing technique for metals. This method uses a laser spot with a small spot diameter, which has the characteristics of high manufacturing accuracy and high density and can achieve a one-time net shape [ 3 , 4 ].…”