日本金属学会誌

J. Japan Inst. Metals, Vol. 48, No. 3 (1984),
pp. 238-247

Effect of Heat Treatment Conditions on Stress Corrosion Cracking Resistance of Alloy X-750 in High Temperature Water

Toshio Yonezawa1, Kichiro Onimura1, Naruo Sakamoto1, Nobuya Sasaguri1, Hidenori Nakata2 and Hiroshi Susukida1

1Takasago Technical Institute, Mitsubishi Heavy Industries, Ltd., Takasago
2Kobe Shipyard & Engine Works, Mitsubishi Heavy Industries, Ltd., Kobe

Abstract:

In order to improve the resistance of the Alloy X-750 in high temperature and high purity water, the authors investigated the influence of heat treatment condition on the stress corrosion cracking resistance of the alloy.
This paper describes results of the stress corrosion cracking test and some discussion on the mechanism of the stress corrosion cracking of Alloy X-750 in deaerated high temperature water.
\noindent The following results were obtained.
(1)  The stress corrosion cracking resistance of Alloy X-750 in deaerated high temperature water remarkably depended upon the heat treatment condition. The materials solution heat treated and aged within temperature ranges from 1065 to 1100°C and from 704 to 732°C, respectively, have a good resistance to the stress corrosion cracking in deaerated high temperature water. Especially, water cooling after the solution heat treatment gives an excellent resistance to the stress corrosion cracking in deaerated high temperature water.
(2)  Any correlations were not observed between the stress corrosion cracking susceptibility of Alloy X-750 in deaerated high temperature water and grain boundary chromium depleted zones, precipitate free zones and the grain boundary segregation of impurity elements and so on. It appears that there are good correlations between the stress corrosion cracking resistance of the alloy in the environment and the kinds, morphology and coherency of precipitates along the grain boundaries.


(Received 1983/08/19)

Keywords:

stress corrosion cracking, nickel-base superalloy, high temperature water, grain boundary, heat treatment, microstructure, mechanism, coherency, chromium depleted zone, segregation


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