Effect of Hydrostatic Pressure on the Corrosion Behavior of a Low Alloy Steel

Abstract

The effect of hydrostatic pressure (HP) on the corrosion behavior of low alloy steel in 3.5% NaCl was studied in a pressure vessel using gravimetric, electrochemical and imaging techniques. The results indicate that HP influences the corrosion behavior of steel to different extents all through the immersion period: in the initial immersion (first 5 days), the corrosion rate at 35 atm is obviously higher than that at 1 atm; which is followed by a period of no obvious difference between the two pressures; and after 15 days, the corrosion rate at 35 atm is only slightly higher than that at 1 atm. Generally, it stimulates the corrosion process, especially during the initial immersion. Further study reveals that the increased corrosion rate at high HP during the initial immersion could be related to the enhanced Cl− adsorption. After the formation of integrated rust layer, HP affects the chemical and physical properties of rust layer. Consequently, it is more conducive for the transport of Cl− at high HP, which further gives rise to the accelerated corrosion. This study aims to be conducive to the fundamental understanding of the corrosion behavior of steel in deep ocean environments.