Study on hydrogen embrittlement and reversibility of hot-stamped aluminized 22MnB5 steel

This study investigated the hydrogen embrittlement behavior of ultrahigh strength hot-stamped aluminized 22MnB5 steel. Hydrogen was introduced through electrochemical charging under different hydrogen conditions to assess their sensitivity to hydrogen-induced cracking. Then, the hydrogen-charged specimens were subjected to the slow strain-rate tensile tests. The fracture morphologies revealed that the charging current density altered the fracture mechanism translated from ductile (uncharged) to quasi-cleavage (0.001A-2h) and a mixture of intergranular and quasi-cleavage fracture (0.1A-2h). Furthermore, the reversibility of hydrogen embrittlement of aluminized specimen was investigated. At low-current density, the coatings were corroded by electrolyte, resulting in additional hydrogen which facilitated the formation of hydrogen-induced cracking and inhibited the restoring of mechanical properties. However, with high-current density, effective cathodic protection ensured the integrity of the surface coating, effectively prohibiting the hydrogen intrusion and promoting the reversibility of hydrogen embrittlement.