Hydrogen embrittlement (HE) in advanced high-strength steels (AHSS) arises from the interaction of absorbed hydrogen with microstructural features, leading to premature cracking and failure under stress. The main mechanisms include:

In AHSS, the complex multiphase microstructure (martensite, retained austenite, ferrite, bainite) amplifies these effects, as hydrogen tends to concentrate in high-stress zones, accelerating crack growth and reducing ductility.

"In advanced high-strength steels, a combination of multiple mechanisms usually occurs simultaneously.

In martensitic steels → the decohesion mechanism and HELP are dominant.

In TRIP/TWIP steels → phase transformation and HELP mechanisms play a more significant role.

In multiphase steels (DP, CP) → hydrogen accumulation in soft and hard phases and microstructural heterogeneity can determine the fracture location."