Effects of the Combined Addition of Zn and Mg on Corrosion Behaviors of Electropainted AlSi-Based Metallic Coatings Used for Hot-Stamping Steel Sheets

Si On Kim; Won Seog Yang; Sung Jin Kim

doi:10.3390/ma13153379

Effects of the Combined Addition of Zn and Mg on Corrosion Behaviors of Electropainted AlSi-Based Metallic Coatings Used for Hot-Stamping Steel Sheets

Materials (Basel). 2020 Jul 30;13(15):3379. doi: 10.3390/ma13153379.

Authors

Si On Kim¹, Won Seog Yang², Sung Jin Kim¹

Affiliations

¹ Department of Advanced Materials Engineering, Sunchon National University, Jungang-ro, Suncheon, Jeonnam 57922, Korea.
² R&D Division, Hyundai Steel, 1480 Bukbusaneop-ro, Songak-eup, Dangjin, Chungnam 31719, Korea.

Abstract

The effects of the combined addition of Zn and Mg on the corrosion resistance of AlSi-based coating for automotive steel sheets were investigated using a variety of analytical and electrochemical techniques. The preferential dissolution of Mg and Zn from MgZn₂/Mg₂Si phases occurred on the AlSi-based coating that had been alloyed with a smaller portion of Zn and Mg, which contributed to the rapid surface coverage by corrosion products with a protective nature, reducing the corrosion current density. On the other hand, localized corrosion attacks caused by the selective dissolution of Mg were also observed in the AlSi-based coating with a smaller portion of Zn and Mg. Such alloying can also worsen its corrosion resistance when coated additionally with electrodeposited paint. The mechanistic reasons for these conflicting results are also discussed.

Keywords: AlSi-based coating; Mg; Zn; corrosion; electrodeposited paint; hot stamping steel.

Abstract

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