5. Coating-substrate interactions

5.1 Fragilization

It can occur when the coating operation is accompanied by the release of significant amounts of hydrogen, and when the substrate metal has high mechanical properties (highly quenched steels, high-speed steels, steels with tensile strength R greater than 1,100 MPa).

Coatings likely to cause substrate embrittlement include cadmium, zinc, copper, silver, nickel and chromium. Without attempting to describe the mechanism of hydrogen embrittlement, it can be...