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Metallurgical and Materials Transactions A

, Volume 29, Issue 2, pp 577–586 | Cite as

Role of microstructural degradation in the heat-affected zone of 2.25Cr-1Mo steel weldments on subscale features during steam oxidation and their role in weld failures

  • R. K. Singh Raman
Article

Abstract

Microstructural degradations in the base metal adjacent to the weld pool, i.e., the heat-affected zone (HAZ), caused during welding of 2.25Cr-1Mo steel, were characterized by electron and optical microscopy of different regions of the weldments. In order to study the influence of the microstructural degradations on scaling kinetics in steam and the resulting subscale features, samples of the base metal, the HAZ, and weld metal specimens were extracted from the weldment and oxidized in an environment of 35 pct steam+nitrogen at 873 K for 10 hours. Oxide scales formed in the three regions and the underlying subscales were characterized using scanning electron microscopy (SEM) and electron probe microanalysis (EPMA). Influence of the “free” chromium content in the three weldment regions on protective scale formation and on the subscale features has been investigated. As the principal achievement, this study has clearly shown the occurrence of oxidation-induced void formation in the subscale zone and grain boundary cavitation in the neighboring area during steam oxidation of the HAZ. This article also discusses the possible role of oxidation-induced void formation and grain boundary cavitation in the inferior service life of welds in 2.25Cr-1Mo steel components.

Keywords

Material Transaction Base Metal Weld Metal Oxide Scale Alloy Matrix 
These keywords were added by machine and not by the authors. This process is experimental and the keywords may be updated as the learning algorithm improves.

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Copyright information

© ASM International & TMS-The Minerals, Metals and Materials Society 1998

Authors and Affiliations

  • R. K. Singh Raman
    • 1
  1. 1.the Department of Communication and Electronic EngineeringRoyal Melbourne Institute of Technology (RMIT)MelbourneAustralia

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