Precipitation behavior of the sigma phase with Ni and Mn content variations in superaustenitic stainless steel weld metal

Journal Article · Mon Oct 15 04:00:00 EDT 2018 · Materials Characterization

DOI:https://doi.org/10.1016/J.MATCHAR.2018.07.006· OSTI ID:22805782

Lee, Changmin; Lee, Youngchai; Lee, Changhee ^[1]; Hong, Seunggab ^[2]

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1. Division of Materials Science and Engineering, Hanyang University, Seoul 133-791 (Korea, Republic of)
2. POSCO Technical Research Lab, Geodong-dong, Nam-gu, Pohang, Gyeongbuk 790-785 (Korea, Republic of)

Highlights: • Precipitation behaviors in the superaustenitic stainless steel welds were researched. • The fraction and size of the sigma phases decreased with addition of both Ni and Mn. • The Ni addition induced the increase of Mo content in a sigma phase. • The Mn prevented the Mo increase in the sigma, and consequently the Mo depletion. • Ni addition elevated the Mo activity, which induced clustering of Mo in the sigma. - Abstract: In this study, precipitation behavior of the sigma phase with variations of the Ni and Mn in superaustenitic stainless steel weld metal was evaluated focused on microstructure and thermodynamic analysis. Experiments were conducted with variation of Ni and Mn based on a 23Cr-17Ni-6Mo superaustenitic stainless steel weld. And GTAW welding was performed on the casted specimens for simulating the weld metal. The weld metal consisted of γ-dendrite and an amount of sigma phases at interdendritic boundaries. And the sigma phase fraction showed decreasing behavior inversely according to addition of the Ni and Mn in the weld metal. From the microstructural analysis, the Ni addition induced increase of Mo content in the sigma phase, which caused the Mo depletion zone around the sigma phase. Whereas, the Mn addition induced replacement of Mo in sigma phase by Mn, so that the Mo depletion zone was not formed. Also, from the Thermo-Calc analysis, it was revealed that Ni addition caused increase of Mo activity, which induced Mo clustering in the sigma phase, while the Mn addition showed opposite effect of the Mo activity.

• OSTI ID: 22805782
• Journal Information: Materials Characterization, Journal Name: Materials Characterization Vol. 144; ISSN 1044-5803; ISSN MACHEX
• Country of Publication: United States
• Language: English

Related Subjects

36 MATERIALS SCIENCE
CHROMIUM COMPOUNDS
DENDRITES
MANGANESE COMPOUNDS
MICROSTRUCTURE
NICKEL COMPOUNDS
PHASE STUDIES
PRECIPITATION
THERMODYNAMICS
WELDED JOINTS