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Influence of microstructure on cavitation in the heat affected zone of a Grade 92 steel weld during long-term high temperature creep

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journal contribution
posted on 19.10.2020, 13:14 authored by X Xu, JA Siefert, JD Parker, Rachel ThomsonRachel Thomson
The microstructure in the heat affected zone of the multi-pass welds constructed using the 9% Cr tempered martensitic steels is complex and susceptible to premature creep failure. In the present research, a systematic investigation has been conducted after long-term creep exposure in the heat affected zone of a multi-pass weld on the 9% Cr Grade 92 steel to identify the sub-optimal microstructures with a high susceptibility to creep cavitation. The characterisation techniques employed include hardness mapping and a range of electron-based microscopy methods. The results provide quantitative data for microstructure and creep cavities. In this case, preferential creep cavitation has been confirmed in the regions within the heat affected zone that possesses a microstructure with an inhomogeneous distribution of the M23C6 carbides and a refined martensitic grain structure. Creep cavities have been observed on the secondary phase particles including the Al2O3, the MnS and the BN phases. The observations from the current research confirm that creep cavitation preferentially occurs in the partially-transformed zones that were subjected to thermal cycles associated with peak temperatures between the Ac1 and the Ac3 transus temperatures during weld fabrication.

History

School

  • Aeronautical, Automotive, Chemical and Materials Engineering

Department

  • Materials

Published in

Materials Characterization

Volume

170

Publisher

Elsevier BV

Version

AM (Accepted Manuscript)

Rights holder

Elsevier Inc.

Publisher statement

This paper was accepted for publication in the journal Materials Characterization and the definitive published version is available at https://doi.org/10.1016/j.matchar.2020.110663.

Acceptance date

20/09/2020

Publication date

2020-09-24

Copyright date

2020

ISSN

1044-5803

Language

en

Depositor

Prof Rachel Thomson. Deposit date: 16 October 2020

Article number

110663