Predicting solid-state phase transformations during metal additive manufacturing: A case study on electron-beam powder bed fusion of Inconel-738

• Published in: Additive manufacturing Vol. 76; p. 103771
• Main Authors: Adomako, Nana Kwabena, Haghdadi, Nima, Dingle, James F.L., Kozeschnik, Ernst, Liao, Xiaozhou, Ringer, Simon P., Primig, Sophie
• Format: Journal Article
• Language: English
• Published: Elsevier B.V 25-08-2023
• Subjects: Additive manufacturing; IN738; Simulation; Thermal cycles; γ′ phase; Thermal cycles; Additive manufacturing; Simulation; γ′ phase; IN738
• ISSN: 2214-8604; 2214-7810
• DOI: 10.1016/j.addma.2023.103771

Metal additive manufacturing (AM) has now become the perhaps most desirable technique for producing complex shaped engineering parts. However, to truly take advantage of its capabilities, advanced control of AM microstructures and properties is required, and this is often enabled via modeling. The current work presents a computational modeling approach to studying the solid-state phase transformation kinetics and the microstructural evolution during AM. Our approach combines thermal and thermo-kinetic modelling. A semi-analytical heat transfer model is employed to simulate the thermal history throughout AM builds. Thermal profiles of individual layers are then used as input for the MatCalc thermo-kinetic software. The microstructural evolution (e.g., fractions, morphology, and composition of individual phases) for any region of interest throughout the build is predicted by MatCalc. The simulation is applied to an IN738 part produced by electron beam powder bed fusion to provide insights into how γ′ precipitates evolve during thermal cycling. Our simulations show qualitative agreement with our experimental results in predicting the size distribution of γ′ along the build height, its multimodal size character, as well as the volume fraction of MC carbides. Our findings indicate that our method is suitable for a range of AM processes and alloys, to predict and engineer their microstructures and properties.
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•Combined modeling approach for site-specific solid state phase transformations.•Semi-analytical heat conduction model simulates thermal profile.•MatCalc thermo-kinetic software predicts solid-state phase transformations.•Application to IN738 electron beam powder bed fusion qualitatively matches experiments.•Microstructure-property predictions suitable for other processes & alloys.