Loughborough University
Browse

File(s) under permanent embargo

Reason: Publisher requirement. Embargo date will be added after publication.

Evaluation of metallurgical risk factors in post-test, advanced 9%Cr creep strength enhanced ferritic (CSEF) steel

journal contribution
posted on 2024-02-05, 11:09 authored by Xiyu Zhang, Stuart RobertsonStuart Robertson, Simon HoggSimon Hogg, Mark JepsonMark Jepson

9wt.% Cr steels are widely used in the design and fabrication of thick section components in combined cycle or coalfired applications for working temperatures of 600~650°C. This family of materials possesses a martensitic microstructure stabilized by precipitates. The presence of nitrides, inclusions or evolution of second-phase particles may increase the metallurgical risk to creep. The chemical composition and microstructural evolution of 9wt.% Cr steels contribute to thermal stability and long-term performance. In some specialist alloys, Ta is added to the composition which causes the formation of fine MX precipitates which are only present at the nanometre scale in tempered martensite, which hinder the recovery of dislocations and the migration of laths to extend creep life. However, the presence of large Ta-containing particles or inclusions in the 9wt.% Cr steels may have a detrimental effect on its creep performance, as they may act as preferred sites for cavity nucleation. To fully appreciate the development of damage in these steels, it is necessary to link the pre- and post-test conditions, evaluate damage in the parent metal, develop procedures that provide consistency of results, and obtain statistically relevant data. The evolution of the Ta-containing phase has been tracked and quantified using a variety of correlative characterization approaches. Utilizing focused ion beam microscopy and two-dimensional electron-based microscopic characterisation, three-dimensional tomography has identified a strong relationship between creep cavities and Tacontaining phases from the early stages of creep.

Funding

EPRI, Electric Power Research Institute, Palo Alto, California, USA

Underpinning Multi-User Equipment

Engineering and Physical Sciences Research Council

Find out more...

History

School

  • Aeronautical, Automotive, Chemical and Materials Engineering

Department

  • Materials

Published in

Materials at High Temperatures

Publisher

Taylor & Francis

Version

  • AM (Accepted Manuscript)

Acceptance date

2023-09-10

ISSN

0960-3409

eISSN

1878-6413

Language

  • en

Depositor

Dr Mark Jepson. Deposit date: 13 September 2023

Usage metrics

    Loughborough Publications

    Exports

    RefWorks
    BibTeX
    Ref. manager
    Endnote
    DataCite
    NLM
    DC