Residual Stress Formation in Component Related Stress Relief Cracking Tests of a Welded Creep-Resistant Steel

Residual Stress Formation in Component Related Stress Relief Cracking Tests of a Welded Creep-Resistant Steel

M. Rhode, A. Kromm, D. Schroepfer, J. Steger, T. Kannengiesser

Abstract. Submerged arc welded (SAW) components of creep-resistant low-alloyed Cr-Mo-V steels are used for thick-walled heavy petrochemical reactors (wall-thickness up to 475 mm) as well as employed in construction of modern high-efficient fossil fired power plants. These large components are accompanied by significant restraints during welding fabrication, especially at positions of different thicknesses like welding of nozzles. As a result, residual stresses occur, playing a dominant role concerning so-called stress relief cracking (SRC) typically during post weld heat treatment (PWHT). Besides specific metallurgical factors (like secondary hardening due to re-precipitation), high tensile residual stresses are a considerable influence factor on SRC. For the assessment of SRC susceptibility of certain materials mostly mechanical tests are applied which are isolated from the welding process. Conclusions regarding the influence of mechanical factors are rare so far. The present research follows an approach to reproduce loads, which occur during welding of real thick-walled components scaled to laboratory conditions by using tests designed on different measures. A large-scale slit specimen giving a high restraint in 3 dimensions by high stiffness was compared to a medium-scale multi-pass welding U-profile specimen showing a high degree of restraint in longitudinal direction and a small-scale TIG-re-melted specimen. The small-scale specimens were additionally subjected to mechanical bending to induce loads that are found during fabrication on the real-scale in heavy components. Results show for all three cases comparable high tensile residual stresses up to yield strength with high gradients in the weld metal and the heat affected zone. Those high tensile stresses can be significant for cracking during further PWHT.

Keywords
Welding, Residual Stresses, Creep-Resistant Steel, Post Weld Heat Treatment, Stress Relief Cracking, 13CrMoV9-10

Published online 9/11/2018, 6 pages
Copyright © 2018 by the author(s)
Published under license by Materials Research Forum LLC., Millersville PA, USA

Citation: M. Rhode, A. Kromm, D. Schroepfer, J. Steger, T. Kannengiesser, ‘Residual Stress Formation in Component Related Stress Relief Cracking Tests of a Welded Creep-Resistant Steel’, Materials Research Proceedings, Vol. 6, pp 185-190, 2018

DOI: https://dx.doi.org/10.21741/9781945291890-29

The article was published as article 29 of the book Residual Stresses 2018

Content from this work may be used under the terms of the Creative Commons Attribution 3.0 licence. Any further distribution of this work must maintain attribution to the author(s) and the title of the work, journal citation and DOI.

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