Turnbull, A; Mingard, K P; Lord, J D; Roebuck, B; Tice, D R*; Mottershead, K J*; Fairweather, N D*; Bradbury, A K* (2011) Sensitivity of stress corrosion cracking of stainless steel to surface machining and grinding procedure. Corros. Sci., 53 (10). pp. 3398-3415.

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Abstract

An investigation has been undertaken to establish the effect of surface preparation method on the susceptibility of a 304H stainless steel to stress corrosion cracking under simulated atmospheric corrosion conditions. MgCl2 was deposited onto four-point bend specimens, which were then placed in a chamber with a relative humidity of 45% and temperature of 60 °C. These test conditions were designed to reflect external exposure of stainless steel components in a nuclear reactor situated in a coastal region but with the severity of the exposure conditions enhanced to allow discrimination of the effect of surface preparation in a short timescale (up to 1500 h). Four surface preparation methods were evaluated: transverse grinding, longitudinal grinding, transverse dressing and transverse milling. For each case, surface topography, near-surface microhardness mapping, residual stress and electron back-scattered diffraction measurements were undertaken. Stress corrosion cracks were observed for the ground and milled specimens but not for the dressed specimens, with cracks originating predominantly at corrosion pits with only a few exceptions. The density of cracks increased in the order: transverse ground, milled and longitudinal ground, with the cracks notably much smaller in length for the transverse ground. The propensity for cracking could be linked to the high residual stress and assoicated nanocrystalline microstructure. There was surprisingly less sensitivity to surface defects induced in the machining, though this may have been a consequence of environment severity enabling ease of pit development in a random fashion.

Item Type:	Article
Keywords:	stainless steel, stress corrosion cracking, surface finish
Subjects:	Advanced Materials Advanced Materials > Corrosion
Identification number/DOI:	10.1016/j.corsci.2011.06.020
Last Modified:	02 Feb 2018 13:14
URI:	http://eprintspublications.npl.co.uk/id/eprint/5242

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