Prediction of reversible α/γ phase transformation in multi-pass weld of Fe-Cr-Ni ternary alloy by phase-field method

Abstract

Duplex stainless steel (DSS) is vulnerable to changes in the α/γ phase fraction due to the dissolution and precipitation of various compounds during multi–pass welding. Thus, prediction of this dissolution and precipitation behavior is key for the development of effective manufacturing strategies. In this study, the kinetics of the dissolution and precipitation phenomena of the γ phase in Fe-Cr-Ni alloy were investigated using the kinetic constants derived by the phase–field method, and the α/γ phase fraction of the multi-pass welds was theoretically investigated. The kinetics of the dissolution and precipitation phenomena were evaluated theoretically and experimentally through optical and scanning electron microscopy. DSSs with different compositions were evaluated to achieve satisfactory correlation. The temperature dependences of the experimental and calculated values were found to be in good agreement, indicating that it is possible to theoretically predict the dissolution and precipitation phenomenon of the γ phase by using the phase-field method presented herein. With regard to the α/γ phase fraction, there was a remarkably high correlation between the results predicted using the kinetic constant of the experimental value and those predicted using the kinetic constant derived from the phase–field method. Therefore, the kinetics-based theoretical results of this study could serve as a resource for predicting the γ phase amount of multi–pass welds in DSSs.

Keywords

• Kinetics
• Modeling
• Simulation
• Phase transformation
• Prediction of γ phase
• Multi-pass weld