Microstructure and nanoindentation studies of M23C6 carbides in Fe-18Cr-8Ni steel after long-term ageing at high temperature. Issue 4 (2nd October 2022)

• Record Type: Journal Article
• Authors: Ben Lenda, O.; Saad, E.; Tara, A.; Jbara, O.
• Is Part Of: Advances in materials and processing technologies. Volume 8:Issue 4(2022)
• Page Start: 3859
• Page End: 3874
• Publication Date: 2022-10-02
• Subjects: Fe-18Cr-8Ni steel -- ageing -- nanoindentation -- microstructure -- M23C6 carbides -- precipitation -- coarsening; Materials -- Periodicals; Manufacturing processes -- Periodicals; 620.1105
• DOI: 10.1080/2374068X.2022.2036443
• Languages: English
• ISSNs: 2374-068X

Abstract

ABSTRACT: Understanding the M23 C6 carbides precipitation sequence aims to determine a correct heat treatment design in order to optimise the mechanical properties of the Fe-18Cr-8Ni steel. In this paper, the ageing influence at 800°C on the mechanical properties and microstructure of this steel has been studied. The aged material was examined with nanoindentation, macrohardness, scanning electron microscopy, light microscopy, and X-ray diffraction techniques. The hardness test results showed a continuous softening of the Fe-18Cr-8Ni steel when increasing the treatment time up to 6000 minutes. The nanoindentation tests revealed a decrease in the nanohardness of the austenite and M23 C6 carbides as the ageing time increased. Before the ageing process, the solution treatment produced completely austenitic steel. After 30 and 60 minutes of ageing, the M23 C6 carbides were located at the grain boundaries. The precipitation of the M23 C6 carbides within the grains was observed from 300 to 6000 minutes of ageing. The coarsening of the M23 C6 carbides occurred at high holding times.