Table of Contents
International Journal of Nuclear Energy
Volume 2014, Article ID 504927, 9 pages
http://dx.doi.org/10.1155/2014/504927
Research Article

Experimental and Theoretical Investigation of Three Alloy 690 Mockup Components: Base Metal and Welding Induced Changes

1Department of Solid Mechanics, KTH Royal Institute of Technology, 100 44 Stockholm, Sweden
2Department of Materials Science and Engineering, KTH Royal Institute of Technology, 100 44 Stockholm, Sweden
3Ringhals AB-Ringhalsverket, 432 85 Väröbacka, Sweden

Received 7 April 2014; Revised 19 June 2014; Accepted 21 June 2014; Published 3 August 2014

Academic Editor: Qunjia Peng

Copyright © 2014 Rickard R. Shen et al. This is an open access article distributed under the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.

Abstract

The stress corrosion cracking (SCC) resistance of cold deformed thermally treated (TT) Alloy 690 has been questioned in recent years. As a step towards understanding its relevancy for weld deformed Alloy 690 in operating plants, Alloy 690 base metal and heat affected zone (HAZ) microstructures of three mockup components have been studied. All mockups were manufactured using commercial heats and welding procedures in order to attain results relevant to the materials in the field. Thermodynamic calculations were performed to add confidence in phase identification as well as understanding of the evolution of the microstructure with temperature. Ti(C,N) banding was found in all materials. Bands with few large Ti(C,N) precipitates had negligible effect on the microstructure, whereas bands consisting of numerous small precipitates were associated with locally finer grains and coarser grain boundary carbides. The Ti(C,N) remained unaffected in the HAZ while the carbides were fully dissolved close to the fusion line. Cold deformed solution annealed Alloy 690 is believed to be a better representation of this region than cold deformed TT Alloy 690.