Improvement of hydrogen embrittlement by void formation at coating layers of Sb-added Al-Si-coated hot-press-forming steels

Al-Si coating prevents the oxidation or decarburization of hot-press forming (HPF) steel. However, the high reactivity of Al with moisture promotes H uptake, and the coating hinders the out-diffusion of absorbed H atoms inside the steel, leading to hydrogen embrittlement (HE). This study added Sb to adjust Fe and Al/Si diffusivity, and forming H-trapping voids within the coating. Simultanesouly, these voids provided routes for the emission of H atoms, thereby improving the resistance to crack propagation during bending. The optimal design of the Al-Si coating by adjusting the Sb content and void fraction would enable extensive applications of HPF steel.

Automated summary

This study added Sb to modulate the diffusion rates of Fe and Al/Si, resulting in the formation of H-trapping voids within the coating. These voids provided pathways for the release of H atoms, improving the resistance to crack propagation during bending. The optimal design of the Al-Si coating by adjusting the Sb content and void fraction would enable extensive applications of HPF steel.