Heavy plate production: demand on hydrogen control

Hydrogen in steels causes various types of cracking, which occur when the a mount of hydrogen in a steel reaches a critical level. This phenomenon resu lts from excessive internal hydrogen pressure, and is associated with the f ormation of cracks at material imperfections, for example non-metallic incl usions. Consequently, cracking can be prevented either by avoiding an exces sive amount of hydrogen or by increasing the critical level for cracking. T hese 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 produce d on the metal surface by a corrosion reaction, for example in a wet H2S en vironment. 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.