Creep Microstructural Evolution of Type IV Cracking in Long-Serviced Dissimilar Steel Welded Joints

Zihao Shen; Fei Gao; Denghui Wang; Yuan Li; Zheng Zhang

doi:10.54097/p5av2j37

Authors

Zihao Shen
Fei Gao
Denghui Wang
Yuan Li
Zheng Zhang

DOI:

https://doi.org/10.54097/p5av2j37

Keywords:

Long-serviced Dissimilar Steel Welded, Heat Affected Zone, Type IV Crack, Grain Boundary Damage

Abstract

A high-temperature creep interruption test at 650°C and 70 MPa was conducted on a long-serviced T92-Super304H welded joint to study Type IV cracking and service-induced damage. The fine-grained heat-affected zone (FGHAZ) displayed lath degradation, precipitate coarsening, and grain boundary damage. During creep, recrystallization and grain recovery occurred in the FGHAZ on the T92 side. Dislocations aggregated around precipitates and at damaged grain boundaries, where Type IV cracks formed and propagated. This accumulation and boundary damage are main mechanisms of Type IV cracking.

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