Creep rupture ductility of ferritic creep resistant steels. (2nd November 2022)

• Record Type: Journal Article
• Authors: Kimura, K.; Sawada, K.
• Is Part Of: Materials at high temperatures. Volume 39:Number 6(2022)
• Page Start: 538
• Page End: 548
• Publication Date: 2022-11-02
• Subjects: Creep rupture ductility -- ferritic creep-resistant steel -- 0.2% offset yield stress -- yield ratio -- creep rupture strength -- creep strength enhanced ferritic steels -- 2.25Cr-1Mo steel; Materials at high temperatures -- Periodicals; High temperatures -- Periodicals; 620.1121705
• DOI: 10.1080/09603409.2022.2058230
• Languages: English
• ISSNs: 0960-3409

Abstract

ABSTRACT: The creep rupture ductility of not only creep strength enhanced ferritic steels but also conventional 2.25Cr-1Mo steels was investigated, focusing on the remarkable decrease in ductility in the long term. The decrease was well described as a function of yield ratio of applied stress and appeared at about 50% of the 0.2% offset yield stress at the creep test temperature with decrease in the yield ratio. A trade-off relation between creep rupture strength and creep rupture ductility was found for Grade T/P23 steels. The similar trade-off relation between creep strength and ductility was observed also for conventional 2.25Cr-1Mo steels. A remarkable drop in creep rupture ductility of quenched and tempered 2.25Cr-1Mo steels was found in conjunction with a large drop in creep rupture strength. This remarkable drop was considered to be caused by microstructural changes due to the inhomogeneous progress of recovery of tempered martensitic microstructure. A modified heat treatment process with intermediate tempering on partially quenched dual phase microstructure was found to have a beneficial effect on creep rupture ductility for Grade P92 steel. This was considered to be the result of the reduction in residual stress introduced by martensitic phase transformation accompanied with shape change and volume expansion.