Integrity Assessment of 10Cr Ferritic Steel/Alloy 617M Dissimilar Metal Weld Joint under Creep Condition

• Published in: Journal of materials engineering and performance 2023-10, Vol.32 (20), p.9295-9308
• Main Authors: Sakthivel, T., Dey, H. C., Parida, P. K., Reddy, G. V. Prasad, Vasudevan, M., Albert, Shaju K.
• Format: Article
• Language: English
• Subjects: Characterization and Evaluation of Materials; Chemistry and Materials Science; Corrosion and Coatings; Engineering Design; Materials Science; Quality Control; Reliability; Safety and Risk; Technical Article; Tribology
• ISSN: 1059-9495; 1544-1024
• DOI: 10.1007/s11665-023-07802-y

Integrity assessment of 10Cr ferritic steel/alloy 617M dissimilar metal weld joint (DMWJ) fabricated from hot-wire narrow-gap TIG (NG-TIG) welding process using alloy 617 filler wire (ERNiCrCoMo-1) was carried out under creep testing at 888 K. Microstructural constituents and hardness across the weld joint (10Cr steel-alloy 617 butter layer-alloy 617 weld metal-alloy 617 M) were found to vary significantly. Alloy 617 weld metal and butter layer have possessed higher hardness as compared to base metals of alloy 617M and 10Cr steel. However, lower hardness was observed in the alloy 617 butter layer, which is adjacent to 10Cr steel, and in the outer edge of HAZ in the 10Cr steel. The carbon migration was predominantly observed across the interface between 10Cr steel and alloy 617 butter layer. Creep tests performed on 10Cr steel and DMWJ at 888 K have revealed the lower creep strain accumulation in DMWJ than the 10Cr steel base metal. An early onset of tertiary creep deformation and consequent premature failure of DMWJ were noticed as compared to the 10Cr steel. Creep rupture strength of the DMWJ was about 31% lower than the 10Cr steel. Fracture in the weld joint has occurred at the interface between 10Cr steel and alloy 617 buttered layer with significant reduction in ductility. The formation of coarse M 23 C 6 precipitates and Laves phase (enriched by Mo and W), oxidation, heterogeneity in strength across the interface have facilitated the extensive cavitation at the interface, thereby leading to premature failure of the DMWJ. Weld strength reduction factor of about 0.69 at 888 K for 10 4  h has been obtained for the DMWJ.