Microstructural Evaluation and Property Change of 5?Wt Pct Al-Zn Coating on Press Hardening Steel During Austenitization
Journal
Metallurgical and Materials Transactions A: Physical Metallurgy and Materials Science
Journal Volume
49
Journal Issue
8
Pages
3715-3728
Date Issued
2018
Author(s)
Abstract
Microstructural evolution of a 5 wt pct Al-Zn coating on press hardening steel was studied in comparison to hot-dip galvanized (GI) and galvannealed (GA) coatings. The results show that the presence of 5 wt pct Al effectively suppresses oxidation during austenitization; meanwhile, the presence of Fe resulting from galvannealing accelerates oxidation. Alloying with Al or Fe in the coating prior to austenitization reduces the susceptibility to liquid metal embrittlement (LME). The presence of Al in the as-coated Zn coating enhances the corrosion resistance in HCl solution and reduces the cathodic kinetics in NaCl solution. However, for sacrificial protection, the austenitized GI steel outperforms the other austenitized-coated steels. Nevertheless, the 5 wt pct Al-Zn coating exhibits better overall performance including high-temperature oxidation resistance, less LME susceptibility, and cathodic protection.
Type
journal article