An assessment of the corrosion behaviour of high-grade alloys in seawater at elevated temperature and under a high velocity impinging flow

Abstract

Laboratory experiments were carried out to investigate the effect of elevated temperature (up to 60 °C) and a high velocity impinging flow on the corrosion behaviour of stainless steels and related Ni-base and Co-base alloys. DC-electrochemical techniques were employed in conjunction with microscopy to determine the extent and mechanisms of attack under the severe imposed conditions. Experiments demonstrated the clear effect of increased temperature in facilitating premature breakdown of passivity on all materials and the effect of the high velocity impinging flow was to further shift the passivity breakdown potential to more active values but not necessarily to result in greater depth of attack. In addition, the study has indicated that the relative resistances of the different materials to attack under static, ambient temperature conditions is altered significantly when they are subjected to elevated temperatures and/or high velocity seawater impingement.