Work

Microstructural Degradation of Super304H after Long-Term Service Exposure

Year: 2025

Type: article

Abstract: Super304H is austenitic steel used predominantly for boiler and turbine components in thermal power plants due to the high strength, excellent creep and oxidation resistance in high-temperature steam environments. Microstructural degradation is inevitable upon long-term high-temperature exposure. Therefore, understanding the processes of degradation is critical for the determination of residual lifetime of the parts. In this study, the hardness, tensile strength and creep strength of a Super304H steel that was in service as a reheater for ~8 years at about 600°C was investigated with corresponding microstructural analysis. Grain growth is evident, but microhardness and tensile strength did not decrease, due to the precipitation of nanosized NbX and Cu-rich particles in grain interior. However, the creep rupture life of the aged S304H steel is ~90% lower at 650°C than that of the virgin S304H, due to the coarsening of σ phase and formation of M 23 C 6 on the grain boundary. Our measurements and analysis of the specimens in this study indicates the remaining service life longer than those in the NIMS database.

Source: Defect and diffusion forum/Diffusion and defect data, solid state data. Part A, Defect and diffusion forum

DOI: 10.4028/p-3forpv

Authors: Li Ming Xu, Yin Sheng He, Keesam Shin

Institutions: Ningbo University of Technology, NingboTech University, University of Science and Technology Beijing, Changwon National University

Language: English

Topic: High Temperature Alloys and Creep

Subfield: Mechanical Engineering

Field: Engineering

Domain: Physical Sciences

Open Access status: hybrid

OpenAlex ID: W4407796223

FWCI:

Cites: 26

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Related to: 10