Effects of Al-Si coating and Zn coating on the hydrogen uptake and embrittlement of ultra-high strength press-hardened steel

SURFACE & COATINGS TECHNOLOGY

卷:374

Article

Jo, Kyoung Rae¹  Cho, Lawrence^1,2  Sulistiyo, Dimas H.¹  Seo, Eun Jung^1,3  Kim, Seong Woo⁴  De Cooman, Bruno C.¹ 

[1] Pohang Univ Sci & Technol, Grad Inst Ferrous Technol, Pohang 37673, South Korea

[2] NIST, Boulder, CO 80305 USA

[3] Colorado Sch Mines, Adv Steel Proc & Prod Res Ctr, Golden, CO 80401 USA

[4] POSCO, Tech Res Labs, Gwangyang 57807, South Korea

关键词: Zn coating;    Al-Si coating;    Press-hardened steel;    Martensite;    Hydrogen embrittlement;    Hot press forming;   

DOI  :  10.1016/j.surfcoat.2019.06.047

来源: Elsevier

【 摘 要 】

Press-hardened steel (PHS), used for automotive safety-related structure parts, is sensitive to hydrogen embrittlement due to its martensitic microstructure. Hydrogen is introduced in PHS during the hot press forming (HPF) process, by an atmospheric corrosion process. In this study, the hydrogen embrittlement behavior of uncoated, aluminized, and galvanized PHSs was investigated. The Al-10%Si coating promoted the absorption of diffusible hydrogen at elevated temperature during the HPF while the reacted coating layer prevented the absorbed hydrogen from out-diffusing through the reacted coating surface layer at room temperature. Therefore, the aluminized PHS showed a greater sensitivity to both the hydrogen uptake and the resultant embrittlement, as compared to the uncoated and galvanized PHSs. Use of galvanized PHS for HPF application reduces the risk of hydrogen embrittlement, since the Zn coating effectively prevents the hydrogen uptake. The greater embrittlement resistance of the galvanized PHS is possibly due to the inhibition of the hydrogen generation reaction by the surface ZnO oxide layer and the low rate of hydrogen transport through the liquid Zn phase.

【 授权许可】

Free