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.