Creep resistance of Fe–Ni–Cr heat resistant alloys for reformer tube applications. Issue 16 (2nd November 2019)

• Record Type: Journal Article
• Authors: Tancret, F.; Laigo, J.; Furtado, J.
• Is Part Of: Materials science and technology. Volume 35:Issue 16(2019)
• Page Start: 1924
• Page End: 1931
• Publication Date: 2019-11-02
• Subjects: Stainless steel -- Fe–Ni–Cr alloy -- Cr7C3 -- Cr23C6 -- NbC -- HP alloys -- refractory steel -- precipitate -- precipitation; Materials science -- Periodicals; Microstructure -- Periodicals; Metallurgy -- Periodicals; 620.1105
• DOI: 10.1080/02670836.2019.1648371
• Languages: English
• ISSNs: 0267-0836

Abstract

Abstract : Relations between microstructure, phase transformations and creep resistance of austenitic Fe–Ni–Cr alloys are investigated. As-cast alloys with different silicon contents and an ex-service tube are submitted to laboratory agings to trigger specific phase transformations, and subsequently creep-tested at 950°C under stresses of 24–48 MPa. As-cast microstructures contain interdendritic chromium-rich M7 C3 carbides with niobium-rich MC carbides. After aging at 950°C, primary M7 C3 carbides transform into chromium-rich M23 C6 carbides, associated to a loss in creep strength. The G phase present in the ex-service alloy is reversed into MC carbides by a heat treatment at 1100°C, associated to a slight decrease in creep resistance. Besides, the addition of silicon is highly detrimental to creep strength. Results can be used for alloy design.