Statistic analyses of industrial experimental datum were done to investigate the effect of pretreatment process, hot-dip process and posttreatment process on spangle size of hot-dip 55%Al-Zn alloy coated steel sheet. The results show that, with the decrease of concentration of degreasing solution, the decrease of RTF dew point temperature, the decrease of temperature at which strip entering into Al-Zn bath, and the increase of injection pressure of air knife, spangle size decreases; with the increase of hydrogen content in RTF, spangle size decreases firstly and then tends to be stable; with the increase of bath temperature, spangle size increases firstly and then decreases; The hot-dip time, the distance between air knife and steel strip, the height of air knife from Al-Zn bath, and the blowing rate of cooling fan have little effect on spangle size; the addition of mixed rare earth doesn’t affect spangle size, while the addition of titanium with trace amount leads to the decrease of spangle size.
Corrosion Behavior of 55%Al-Zn Alloy Coated Steel Sheet near its Shear Cut Edge in Salt Spray Test