Abstract: Oxidation-reduction process is an effective way to improve the galvanizability of Si and Mn added advanced high strength steel (AHSS). Due to the suppression of external oxidation by reduced iron, the wettability of molten zinc can be significantly improved, while the control of coating adhesion is still a challenge. An industrial galvanized 980 MPa AHSS having poor coating adhesion was tested by 0T bending and investigated by GDOES and SEM, cross-sectional specimen was prepared by FIB and examined by HR-TEM. It was found that the adhesion between the coating and the reduced iron was strong due to the formation of enough Fe-Al inhibition layer. However, the adhesion between the reduced iron and matrix was poor due to the formation of a continuous layer of external Si and Mn oxides at the interface of reduced iron and matrix. It is suggested to precisely control both the oxidation and reduction process to achieve a good coating adhesion.
Authors: Xinyan Jin, Jiajie Chen, Guangkui Hu, and Li Wang
Keywords: coating adhesion, oxidation-reduction, galvanized AHSS