METHOD FOR PRODUCING HOT-ROLLED SHEETS OF LOW-ALLOY STEEL Russian patent published in 2017 - IPC C21D8/02 C22C38/00 

FIELD: metallurgy.

SUBSTANCE: method includes production of continuously cast steel billet containing wt %: C 0.09-0.12, sum Si+Mn=2.00-2.60, sum of Cr+Ni+Cu=0.30-0.80, sum of V+Nb+Ti=0.010-0.050, nitrogen not more than 0.008, aluminium not more than 0.050, sulfur not more than 0.010, phosphorus not more than 0.018, iron and unavoidable impurities-the rest, wherein peritectic potential F should be less than -0.01% or more than 0.01%, austenization of continuously cast billet is carried out up to 1190-1215°C, finish rolling is started at temperature of 730 -770°C, then the sheets are cooled slowly to temperature below 100°C and subjected to heat treatment by placing thereof into furnace at temperature no more than 650°C, heating to A_c3+(10-50)°C and holding for 3-4 min/mm with provision of uniform ferrite-pearlite structure in the finished sheet with the size of the ferrite-pearlite structure with actual size of ferrite grain not more than 8 points.

EFFECT: producing hot-rolled sheet 48-100 mm thick of low-alloy steel to manufacture high-duty structures, providing mechanical properties not lower than 325 strength class and impact strength KCU at temperature up to minus 70 degrees, and 1 class guarantee of ultrasonic check.

4 cl, 3 tbl