METHOD OF PRODUCING HOT-ROLLED COIL OF LOW-ALLOY STEEL Russian patent published in 2019 - IPC C21D8/02 C22C38/00 

FIELD: metallurgy.

SUBSTANCE: method involves melting and continuous pouring of steel, heating and hot rolling of workpiece, accelerated cooling of rolled strip and its further coiling. At that steel is cast containing wt%: carbon 0.20÷0.27; manganese 0.80÷1.40; silicon 0.20÷0.30; chromium not more than 0.30; nickel not more than 0.30; copper not more than 0.30; titanium not more than 0.040; aluminum 0.015÷0.060; nitrogen not more than 0.012; sulfur not more than 0.010; phosphorus not more than 0.015; calcium not more than 0.020; molybdenum not more than 0.040; iron and impurities – balance. Contents in melted steel of carbon, manganese, sulfur and phosphorus corresponds to ratio (24.63⋅C+1.22⋅Mn+15⋅S+2.35⋅P)≤8.46, in which each symbol of a chemical element denotes content of said element in steel in wt%. Billet is heated in heating furnace at temperature of 850÷1050 °C, time of billet in heating furnace t in min corresponds to ratio t=(k₁⋅C)±10, where k₁ – empirical coefficient making k₁=100÷200, C – content of carbon in steel in wt%. During accelerated cooling of rolled strip at least in five points along the length of discharge roll table to its top surface water is additionally supplied through nozzles, wherein said nozzles are installed such that the angle formed by axis of nozzle channel and horizontal plane is not straight, wherein flow rate of water supplied in said manner corresponds to range of 10÷15 m³/hour per 1 m² surface of strip.

EFFECT: reduced segregation and structural inhomogeneity of rolled stock, achievement of required level of its mechanical properties with increase of uniformity of their distribution.

7 cl, 2 tbl