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Investigation of microstructural evolution and creep rupture behaviour of 9% Cr MarBN steel welds

journal contribution
posted on 08.06.2020, 08:18 by X Xu, A Benaarbia, D Allen, Mark Jepson, W Sun
The weldments made from the 9-12% Cr tempered martensitic steel are associated with a complex microstructure arising from complicated thermal histories of the fusion and heat affected zones. The complicated microstructural and micro-mechanical states in these critical regions provide a challenge for the determination of creep failure mechanisms. Based on detailed metallographic examination, the microstructural distribution in the heat affected zone of the welds constructed using a recently developed 9% Cr MarBN steel, IBN-1, has been identified and classified into Equiaxed Zone (EZ), Duplex Zone (DZ) and Over-tempered Zone (OZ). Cross-weld testing performed at 650°C has revealed a significant reduction in creep life as compared to bulk material. Creep rupture has been shown to occur in the parent metal region with a ductile manner at a high stress, whereas creep rupture initiates in the DZ region in an intergranular manner at a low stress. Detailed metallographic investigation has further revealed a higher damage susceptibility in the regions along the pre-existing Prior Austenite Grain Boundaries (PAGBs). The diffusional reaustenitisation of local microstructure along the PAGBs leads to a lower strength of matrix in combination with a lack of intergranular precipitates as compared to the surrounding microstructure formed after displacive reaustenitisation

Funding

(EPSRC) Advanced Industrial Manufacture of Next-Generation MARBN Steel for Cleaner Fossil Plant : EP/N509942/1

History

School

  • Aeronautical, Automotive, Chemical and Materials Engineering

Department

  • Materials

Published in

Materials Science and Engineering: A

Volume

791

Publisher

Elsevier BV

Version

AM (Accepted Manuscript)

Rights holder

© Elsevier

Publisher statement

This paper was accepted for publication in the journal Materials Science and Engineering: A and the definitive published version is available at https://doi.org/10.1016/j.msea.2020.139546

Acceptance date

09/05/2020

Publication date

2020-05-18

Copyright date

2020

ISSN

0921-5093

Language

en

Depositor

Dr Mark Jepson . Deposit date: 5 June 2020

Article number

139546

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