HIGH-STRENGTH SHEET STEEL WITH COATING OBTAINED WITH HOT DIPPING, WHICH HAS HIGH IMPACT STRENGTH AT LOW TEMPERATURES, FOR BEING USED IN FORMING, AND MANUFACTURING METHOD THEREOF Russian patent published in 2011 - IPC C22C38/14 C21D8/02 C21D9/46 C23C2/08 

FIELD: metallurgy.

SUBSTANCE: high-strength cold-rolled sheet steel and its manufacturing method is proposed. Steel contains the following, wt %: C 0.0005 to 0.0050, Si: more than 0.3 to 1.0, Mn 0.70 to 2.0, P 0.05 and less, Ti 0.010 to 0.050, Nb 0.010 to 0.040, B 0.0005 to 0.0030, S 0.01 and less, Al 0.01 to 0.30, N 0.0010 to 0.01, Fe and inevitable impurities are the rest. At that, TB*=(0.11-[Ti])/(ln([B]×10000)) is 0.03 to 0.06 while meeting the ratio [P]≤10×[B]+0.03. Method involves continuous casting of molten steel so that slab is obtained, hot rolling of slab at 1050°C - 1245°C during 5 hours, with rolling end temperature of Ar₃ to 910°C and rolling of hot-rolled sheet at temperature of 750°C and less, cold rolling of hot-rolled sheet with cold rolling degree of 50% and more so that cold-rolled sheet of the specified thickness is obtained and rolling of the sheet, annealing of the roll from cold-rolled sheet at recrystallisation temperature and more and application of coating to the sheet surface by dipping the roll.

EFFECT: steel has strength of 380-540 MPa, high ductility, embrittlement resistance and impact strength of zone of seam weld of contact welding at low temperature.

20 cl, 5 dwg, 6 tbl, 38 ex