Corrosion resistance of different Al-Si coated hot-press-forming steels
[Introduction] The anticorrosion performance of hot-press-forming steel with Al-Si coating is greatlyaffected by the coating thickness. It is necessary to compare the corrosion resistance of three types of Al-Si coated hot-press-forming steel sheets used in automobiles i.e. the normal coating sheet with an Al-Si coating thickness of 20-33 μm, the thin coating sheet with an Al-Si coating thickness of 6-14 μm, and the tailor-rolled blank (TRB). [Method] The neutral salt spray (NSS) test of the steel sheets before and after hot-press forming was carried out. [Result] Before hot-press forming, red rust did not appear on normal coating sheet until 1109 hours of NSS test, but appeared after 283 hours on the thin coating sheet and after 618 hours on the thin area of TRB. After hot-press forming and electrocoating, the width of one-side corrosion expansion was 0 mm for the normal coating sheet, 4.0 mm for the thin coating sheet, and 0.5 mm at the 2.3 mm-thick area and 2.0 mm at the 2.0 mm-thick and 1.8 mm-thick areas for TRB. [Conclusion] The anticorrosion performance of the Al-Si coated steel sheets without hot-press forming is related to the total thickness of Al-Si coating. The thickness of diffusion layer between the coating and substrate has a significant impact on the corrosion of Al-Si coated steel sheet after hot-press forming and electrocoating. The corrosion resistance of TRB is better than that of the sheets with thin coatings, but worse than that of the ones with a normal coating thickness.
万方数据
维普
