3D Modeling of the Solidification Structure Evolution of Superalloys in Powder Bed Fusion Additive Manufacturing Processes

Laurentiu Nastac

doi:10.3390/met11121995

Abstract

Recently, a few computational methodologies and algorithms have been developed to simulate the microstructure evolution in powder bed fusion (PBF) additive manufacturing (AM) processes. However, none of these have attempted to simulate the grain structure evolution in multitrack, multilayer AM components in a fully 3D transient mode and for the entire AM geometry. In this work, a multiscale model, which consists of coupling a transient, discrete-source 3D AM process model with a 3D stochastic solidification structure model, was applied to quickly, efficiently, and accurately predict the grain structure evolution of IN625 alloys during Laser Powder Bed Fusion (LPBF). The capabilities of this model include studying the effects of process parameters and part geometry on solidification conditions and their impact on the grain structure formation within multicomponent alloy parts processed via AM. Validation was accomplished based on single-layer LPBF IN625 benchmark experiments, previously performed and analyzed at the National Institute of Standards and Technology (NIST), USA. This modeling approach can also be used to quantitatively predict the solidification structure of Ti-6Al-4V alloys in electron beam AM processes.

Highlights

Shalchi Amirkhiz andThe main aim of this study is to validate a multiscale mesoscopic modeling approach to predict the microstructure evolution of alloys during powder bed fusion processes (e.g., Electron Beam Additive Manufacturing (EBAM) and selective laser melting (SLM)processes [1,2])
The isopleth section of the Ni-Cr-Nb-Fe-Mo phase diagram with 21 wt. % Cr, 5 wt. % Fe, 9 wt. % Mo, and 0.8 wt. % Co is shown in Figure 1 in [18]
The coupled multiscale model was successfully validated against the benchmark experiments performed by National Institute of Standards and Technology (NIST), Figure 4. 3D grain structure simulation results (2D and 3D plots)

Summary

Introduction

Shalchi Amirkhiz andThe main aim of this study is to validate a multiscale mesoscopic modeling approach to predict the microstructure evolution of alloys during powder bed fusion processes (e.g., Electron Beam Additive Manufacturing (EBAM) and selective laser melting (SLM)processes [1,2]). The main aim of this study is to validate a multiscale mesoscopic modeling approach to predict the microstructure evolution of alloys during powder bed fusion processes (e.g., Electron Beam Additive Manufacturing (EBAM) and selective laser melting (SLM). Laser Powder Bed Fusion (LPBF) products, including the rapid solidification microstructure of IN718, is presented in [3]. It is well-known [3,4] that solidification maps can serve as a guide for estimating microstructures with respect to temperature gradient (G) and solidification rate (R) parameters. An accurate predictive microstructure model would be an extremely useful tool for assisting in AM product quality control. Due to the complexity of the AM process, solidification maps are not accurate enough to predict the formation of microstructures.

Objectives

Results

Conclusion