Investigation of Corrosion and Hydrogen Entry Behavior under Atmospheric Environment by Real-time Monitoring Techniques

Abstract

To develop high strength steel sheets with high resistance to hydrogen embrittlement, it is necessary to clarify the mechanism of hydrogen entry into steel. Hydrogen entry is caused by the corrosion reaction under atmospheric environment. However, the relationship between hydrogen entry and corrosion behavior, and the influence of environmental factors on the hydrogen entry such as temperature, relative humidity （RH） and salt deposition is not fully understood. In this study, simultaneous monitoring of both hydrogen entry and corrosion rate was employed to investigate the influence of environmental factors on hydrogen entry and corrosion behavior. The monitoring was conducted under the atmospheric exposure test.

As a result, both the hydrogen entry and the corrosion rate increased with an increase of amount of salt deposition. In addition, the corrosion rate increased with an increase of RH, whereas the hydrogen had been permeated the most at the medium RH. The mechanism of the hydrogen entry at the medium RH range was assumed to be related to lowering pH in high [Cl－] environment.