Environmentally assisted cracking crack initiation in nickel-based alloy dissimilar metal welds in doped and pure steam and pressurized water reactor water

Aki Toivonen; Hannu Hänninen; Tapio Saukkonen; Pertti Aaltonen

doi:10.5006/2339

Environmentally assisted cracking crack initiation in nickel-based alloy dissimilar metal welds in doped and pure steam and pressurized water reactor water

Aki Toivonen
, Hannu Hänninen
, Tapio Saukkonen
, Pertti Aaltonen

Aalto University
VTT (former employee or external)

Research output: Contribution to journal › Article › Scientific › peer-review

6 Citations (Scopus)

Abstract

Environmentally assisted cracking (EAC) susceptibilities of Alloys 600, 690, and their weld metals with and without weld defects were benchmarked in pure and doped hydrogenated steam at 400°C and pressurized water reactor (PWR) water at 360°C on four-point bend (0.35% to 1.1% strain) and U-bend specimens (5% strain). Contrary to the expectations, no EAC initiation from existing weld defects was observed. As expected, Alloy 600 and its weld metals were much more prone to EAC initiation than Alloy 690 and its weld metals. Oxide structures remain the same in doped and pure steam and PWR water, although the environment has an impact on the EAC initiation times and oxidation rates. Because of the similar oxide structures, the EAC mechanism is assumed to be the same in all studied environments.

Original language	English
Pages (from-to)	808-821
Journal	Corrosion
Volume	73
Issue number	7
DOIs	https://doi.org/10.5006/2339
Publication status	Published - 1 Jul 2017
MoE publication type	A1 Journal article-refereed

Funding

The three projects within which the experimental work was performed were funded by Tekes, Teollisuuden Voima Oyj (TVO), Fortum Power and Heat Oy, Vattenfall Aktiebolag, OKG Aktiebolag, Fennovoima Oy, VTT Technical Research Centre of Finland, and Aalto University School of Engineering, which is gratefully acknowledged. Additional acknowledgments belong to STUK - Radiation and Nuclear Safety Authority of Finland for participating to the projects as a monitoring party.

Keywords

dissimilar metal weld
environmentally assisted cracking
nickel alloys
steam
stress corrosion cracking

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10.5006/2339

Cite this

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abstract = "Environmentally assisted cracking (EAC) susceptibilities of Alloys 600, 690, and their weld metals with and without weld defects were benchmarked in pure and doped hydrogenated steam at 400°C and pressurized water reactor (PWR) water at 360°C on four-point bend (0.35\% to 1.1\% strain) and U-bend specimens (5\% strain). Contrary to the expectations, no EAC initiation from existing weld defects was observed. As expected, Alloy 600 and its weld metals were much more prone to EAC initiation than Alloy 690 and its weld metals. Oxide structures remain the same in doped and pure steam and PWR water, although the environment has an impact on the EAC initiation times and oxidation rates. Because of the similar oxide structures, the EAC mechanism is assumed to be the same in all studied environments.",

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AU - Toivonen, Aki

AU - Hänninen, Hannu

AU - Saukkonen, Tapio

AU - Aaltonen, Pertti

PY - 2017/7/1

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AB - Environmentally assisted cracking (EAC) susceptibilities of Alloys 600, 690, and their weld metals with and without weld defects were benchmarked in pure and doped hydrogenated steam at 400°C and pressurized water reactor (PWR) water at 360°C on four-point bend (0.35% to 1.1% strain) and U-bend specimens (5% strain). Contrary to the expectations, no EAC initiation from existing weld defects was observed. As expected, Alloy 600 and its weld metals were much more prone to EAC initiation than Alloy 690 and its weld metals. Oxide structures remain the same in doped and pure steam and PWR water, although the environment has an impact on the EAC initiation times and oxidation rates. Because of the similar oxide structures, the EAC mechanism is assumed to be the same in all studied environments.

KW - dissimilar metal weld

KW - environmentally assisted cracking

KW - nickel alloys

KW - steam

KW - stress corrosion cracking

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DO - 10.5006/2339

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Environmentally assisted cracking crack initiation in nickel-based alloy dissimilar metal welds in doped and pure steam and pressurized water reactor water

Abstract

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Keywords

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