Multi-Phase-Field Modeling of Transformation Kinetics at Multiple Scales and Its Application to Welding of Steel

Abstract

Production processes of structural materials generally involve a variety of microstructural evolutions, spatiotemporal scales of which are different by several orders of magnitude. In this study, a multi-phase-field model for simulating transformation phenomena at multiple scales is developed by considering mesoscopic kinetics of interest based on diffuse interface description without curvature effect. In particular, the present model is developed for simulations of microstructural evolutions during welding of carbon steels. In this model, the motion of dendrite envelope is described to simulate solidification not at a dendritic scale but at a scale of grain structure. Moreover, the pinning effect is described based on a mean-field approximation, which allows for simulations of grain growth with existence of very fine particles. The present model is applied to two-dimensional simulations for welding processes of carbon steel. The microstructural evolution involving the melting, solidification, austenite grain growth and pinning effect due to very fine particles is demonstrated.

Materials Integration for Accelerating Research and Development of Structural Materials

“…One of the challenges is to apply multi-phase field modeling to simulate the phase transformation of steels in the welding process. 7) In order to evaluate thermodynamic and interfacial parameters that are necessary for the phase field simulation, the molecular dynamic simulation was conducted. 8) The target materials for which the microstructure is predicted by the phase-field method has been expanded to Nickel-based superalloys.…”

“…Most of them came from the above-mentioned projects, including performance predictions such as creep, 2) fatigue, 35) and Hydrogen embrittlement 6) and microstructure prediction. 7,8) Furthermore, another special issue was edited in November, 2020 in Materials Transactions (Vol. 61, No.…”

Development of Microstructure Simulation System in SIP-Materials Integration Projects

“…Figure 1 shows an example of a £-phase polycrystalline microstructure calculated based on the provided thermal history. 18) The top left corner is the point heat source location. The £-phase has formed columnar shape in the region that was a melt pool.…”

Phase Field Modeling of Ghost Diffusion in Sn-Ag-Cu Solder Joints

“…PFM has been utilized to study solid-state phase transformations, precipitate growth, grain growth, solidification and melting and as well phase transformations due to an external field (uniaxial stress, hydrostatic pressure etc.) [1], [2]. In addition, PFM facilitate in describing phase change mechanisms using a theoretical framework where, availability of experimental data can be challenging [3].…”