Study on Hot Dip and Coating Structure of 55% Al-Zn Alloy Coated Steel

Hot dip galvanizing treatments of Galvalume were studied by using methods of Gleeble thermal simulation experiment and optical microscopy(OM), scanning electronic microscopy (SEM), X-ray energy dispersive analysis(EDAX), X-ray diffraction(XRD) and so on. Meanwhile, surface morphology, microstructure, phases and the respective compositions of Al-Zn alloy coating plate were investigated, the formation of hot dipped 55％Al-Zn alloy coating were analyzed. The results show that to get better coated surface, in-zinc pot temperature should be controlled in the range of 590~610°C, and height of air-knife nozzle should be kept in the range of 150~200mm. Surface layer of 55％Al-Zn alloy coating is covered by Al-Zn alloy, the intermediate alloy layer is consisted of binary and ternary compounds, such as θ phase (FeAl3), Al0.3Fe3Si0.7 and Al3.21Si0.47.