HOT-ROLLED SHEET OF LOW-ALLOY STEEL WITH THICKNESS FROM 15 TO 165 mm AND METHOD OF ITS PRODUCTION Russian patent published in 2017 - IPC C22C38/58 C22C38/50 C21D8/02 

FIELD: metallurgy.

SUBSTANCE: invention relates to production of hot-rolled sheets of low alloy steel with a thickness from 15 to 165 mm, for example, production of shut-off fittings of oil and gas pipelines, as well as structures operating at low temperatures up to -60°C. The steel has the following chemical composition, wt %: carbon 0.07-0.13, silicon 0.40-0.75, manganese 1.40-1.80, aluminium not more than 0.06, sulfur not more than 0.01, phosphorus not more than 0.018, total content of chromium, nickel and copper not more than 0.60, titanium not more than 0.03, vanadium not more than 0.08, niobium not more than 0.05, molybdenum not more than 0.05, nitrogen not more than 0.008, the rest is iron and impurities. The metallographic structure of the sheet includes from 10% to 15% of pearlite, the rest is ferrite. The points of non-metallic inclusions are not more than 2.5 by average, not more than 3 by maximum, the points of grain is not more than 8, the banding is not more than 2 points, and carbon equivalent Ceq is not more than 0.43%.

EFFECT: sheets to be manufactured have yield strength at least 265 MPa, ultimate strength at least 430 MPa, and KCV impact strength at minus 60 degrees.

4 cl, 2 tbl