Phase field as a front propagation method for modeling grain growth in additive manufacturing

Abstract

A mesoscopic grain-envelope model applying a phase-field front-propagation method is developed to simulate grain growth under additive manufacturing process conditions. The envelope represents the outer surface of dendritic grains through a diffuse interface. While a modified heat-conduction model that incorporates moving heat sources and latent-heat release provides the evolution of local thermal field. Envelope propagation is determined from microscopic-solvability-based kinetic law. The model is validated through two- and three-dimensional simulations and subsequently applied to examine the influence of material and process parameters on microstructure evolution. The results demonstrate that the proposed mesoscopic model offers an efficient and predictive approach for modeling grain growth during multi-pass and multi-layer build-up in additive manufacturing.

Figures (6)

• Figure 1: Schematic illustration of a) Envelop around dendrite branches and b) Equivalent envelop surface, adapted from steinbach_three-dimensional_1999
• Figure 2: 2D simulated grain structure due to single track melting (a) Simulated grain structure along with the melt pool geometry. (b) Grain interfaces (c) Temperature distribution towards the end of melting
• Figure 3: 3D simulated grain structure due to single track melting (a) Initial microstructure (b) Intermediate stage of melting (c) Final stage of melting
• Figure 4: Difference in undercooled region as a result of substrate temperature a) 1100 K and b) 600 K for the material coefficient a= 2500
• Figure 5: Difference in undercooled region as a result of substrate temperature a) 1100 K and b) 600 K for the material coefficient a= 4500