Heavy plate production: demand on hydrogen control

Hydrogen in steels causes various types of cracking, which occur when the amount of hydrogen in a steel reaches a critical level. This phenomenon results from excessive internal hydrogen pressure, and is associated with the formation of cracks at material imperfections, for example non-metallic inclusions. Consequently, cracking can be prevented either by avoiding an excessive amount of hydrogen or by increasing the critical level for cracking. These two cases are demonstrated from the points of view of steelmaking and plate production. In certain applications, the hydrogen content in a steel may be increased by the absorption and diffusion of atomic hydrogen produced on the metal surface by a corrosion reaction, for example in a wet H2S environment. This phenomenon can lead to hydrogen induced cracking (HIC). The damage mechanism as well as the main strategy to prevent hydrogen induced cracking is described in detail.