Effect of dew point on hot-dip galvanizing behavior of a high-manganese TWIP steel for automotive application

摘要

The effect of dew points(-50,-l0 and+10℃)on the galvanizing properties of a high-manganese twinning-inducedplasticity(TWIP)steel was studied.Scanning electron microscopy(SEM),glow discharge optical emission spectrometry(GDOES)and X-ray photoelectron spectroscopy(XPS)were used for microscopic observation and qualitative analysis of the interfacial layer between the steel surface and the zinc layer after hot-dip galvanizing.SEM analysis results show thatthree diffcrent morphologies of metallic oxides are formed on the interfacial layer under the different dew points.GDOES results show that Al is present in the molten zinc,reacting with Fe on the steel surface to form Fe2Al5,which can increasethe galvanizing properties.XPS results show that the valence states of Mn in the interfacial alloy layer are Mn'*and Mn*+,and the valence stales of Fe are Fe^0,Fe^2+and Fe^3+.The experimental results show that the hot-dip galvanizing performanceis the best at-10℃ and the formation of Mn and Fe intermetallic oxides has a bad effect on hot-dip galvanizing behaviorof the high-manganese TWIP steel.The types of the formed surface oxides(MnO,Mn3O4,Mn2O3,FeO3,and Fe2MnO4)onthe surface of the steel sheet are confirmed.It can obtain the best hot-dip galvanizing performance of the high-manganese TWIP steel by controlling the dew point from-10 to-5℃.