The Corrosion Mechanism of Zn-5%Al-0.3%Mg Coating

Abstract

A new hot dip Zn-5%Al-0.3%Mg alloy coating was performed on cold rolled common steel. The hot-dip process was executed by self-made hot dip galvanising simulator (China patent, No.201010160353). The corrosion resistance of alloy-coated steels was detected by neutral salt spray test . SEM and EDS test results demonstrate that Mg is mainly distributed in the crystal boundary. XRD test results shows corrosion product of Zn-5%Al-0.3%Mg alloy coating is mainly Zn5(OH)8Cl2•H2O. The characteristic of Zn5 (OH)8Cl2•H2O is dense and insoluble, so it is protective. In order to study the anticorrosion mechanism, all the tests of the Zn-5%Al-0.3%Mg alloy were carried out with Zn-5%Al coating together.

The Effects of RE and Si on the Thickness and Cross Section Morphology of Zn-6Al-3Mg Alloy Coating

“…The hot dipping process was as follows: alkaline degreasing (NaOH, wt.15%) at 60 °C for 5 min with a soft brush → water flushing → acid pickling in HCl solution (18 vol. %) for 3 min to remove iron oxides → water flushing → electroplating [16] → dried at 120 °C for 20 min in the oven → hot dipping. The immersing time of steel plates in the zinc alloy bath and the temperature of the zinc alloy bath used in this study were 6s and 530 °C, respectively.…”

Deformation analysis of ZnMgAl coated steel sheet using digital image correlation (DIC) system

“…This however requires high cracking resistance both of the steel sheet and coating during the roll-forming process. Even a micro damage of the coating may lead to cracking in the most deformed areas and may be the cause of the deteriorations in the in-service corrosion resistance [5][6][7]. Thus, obtaining the information of the correlation between microstructure and mechanical properties during the roll forming of open-joint tube process is necessary.…”