Zhou, S; Turnbull, A (2003) Effect of oxygen and chloride on pitting and stress corrosion cracking of steam turbine disc steel. NPL Report. MATC(A)133

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Abstract

Long term exposure tests, up to 1 year, have been carried out on a 3% NiCrMoV steam turbine disc steel in the form of cylindrical tensile test specimens self-loaded to 90% of s 0.2 and exposed to three environmental conditions, viz. deaerated pure water, aerated pure water, and aerated water containing 1.5 ppm of chloride ion. The distribution of pit depths was analysed and where appropriate the length of initiated cracks. Pitting occurred in all environments but the density and depth of pits in the chloride-containing medium was markedly greater. The aerated pure water gave rise to a somewhat higher density of pits than the deaerated pure water but the maximum depths did not vary so much. Stress corrosion cracking was observed in the chloride-containing water but only above a critical pit depth of between 60 µm and 70 µm. In contrast, no cracking was observed for the aerated or deaerated pure water despite pit depths up to 200 µm.

Item Type:	Report/Guide (NPL Report)
NPL Report No.:	MATC(A)133
Subjects:	Advanced Materials Advanced Materials > Corrosion
Last Modified:	02 Feb 2018 13:16
URI:	http://eprintspublications.npl.co.uk/id/eprint/2701

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