VDA 238-200 (11/2020)

Components made of high-strength steel can show brittle failure due to the effect of hydrogen. This often occurs with a time delay and without warning.

In terms of metal physics, hydrogen-induced cracking or hydrogen embrittlement is defined as a material damage induced by atomic hydrogen present in or diffused into the metal lattice. This effect is known either as hydrogen-induced stress corrosion cracking (HISCC, german HISRK) or delayed hydrogen-induced cracking (or delayed fracture).

Material damage caused by hydrogen can only occur if the following boundary conditions are simultaneously fulfilled, see Figure 1:

•         A material with sufficient strength and critical microctructure,
•         a sufficient supply of diffusible hydrogen, e.g. from corrosion processes or acidic media, and
•         a critical stress state, e.g. high constant tensile stresses at the magnitude of the material yield stress.