METHOD OF PRODUCING COLD-ROLLED HOT-DIP-GALVANISED ROLL WITH POLYURETHANE COATING Russian patent published in 2018 - IPC C21D8/04 C23C28/00 

FIELD: metallurgy.

SUBSTANCE: invention relates to ferrous metallurgy. To increase the strength of rolled products with a polyurethane coating during a bending test from 3T to less than 1T, the method includes hot rolling a steel strip of low-carbon, microalloyed steel, wt%: carbon not more than 0.005, silicon no more than 0.04, manganese 0.08–0.15, sulphur no more than 0.010, phosphorus not more than 0.015, chromium not more than 0.04, nickel not more than 0.04, copper not more than 0.04, aluminium not more than 0.070, nitrogen not more than 0.005, titanium not more than 0.100, molybdenum not more than 0.008, niobium not more than 0.005, vanadium not more than 0.008, iron and unavoidable impurities – the balance, coiling into a roll, etching, cold rolling, degreasing, continuous annealing, application of a zinc coating weighing not more than 300 g/m², cooling, pinch rolling, coiling into a roll and applying a polyurethane coating in the polymer coating line, wherein the temperature at the end of hot rolling and coiling is set to 840–900 °C and 660–720 °C, respectively, continuous annealing of the cold-rolled strip is carried out at a temperature of 700–850 °C, pinch rolling is carried out with a reduction of 0.75–1.2 %, the total thickness of the polyurethane coating is 40–50 mcm. In addition, pinch rolling of the galvanized strip is carried out on rolls with roughness Ra 2.2–2.6 mcm, and after pinch rolling, the strip is straightened further.

EFFECT: higher strength of rolled products with polyurethane coating.

3 cl, 2 tbl