FIELD: metallurgy.
SUBSTANCE: method for obtaining steel plate with Sn-Zn system coating involves application of pre-coating from Fe-Ni alloy with nickel content of 10-80 wt %, iron - the rest, dipping of plate to molten metal bath in order to apply Sn-Zn system coating at the bath temperature of 240-300°C and dipping time of 2-15 seconds for the coating containing 1 to 8.8 wt % Zn to be formed on the plate, the rest is 91.2-99.0 wt % Sn and inevitable impurities, cooling of coating with speed of 10-30°C/sec, measurement by means of differential scanning calorimetry in order to obtain differential scanning calorimetric curve for steel plate equipped with Sn-Zn system coating, and estimation on the basis of differential scanning calorimetric curve of microstructure of the applied coating layer, which shall meet the following condition: (endothermic fusion heat value induced with primary crystals Sn)/ {endothermic fusion heat value induced with primary crystals Sn) + (endothermic fusion heat value induced with eutectic crystals Sn-Zn)} ≥ 0.3, at that, for the above microstructure, the endothermic peak temperature induced with fusion of primary crystals Sn is 200°C or more, and 230°C or less, and endothermic peak temperature induced with fusion of eutectic crystals Sn-Zn, is 198°C or more and less than 200°C.
EFFECT: steel plate with the obtained coating has high corrosion resistance, formability and weldability, long-term resistance to impact of contaminated petroleum, and can be used for fuel tanks.
4 cl, 2 dwg, 4 tbl, 4 ex
