THICK SHEET OF STRUCTURAL STEEL FOR MANUFACTURING DETAILS OF WELDED STRUCTURES AND METHOD FOR ITS PRODUCTION IN NORMALIZED CONDITION Russian patent published in 2017 - IPC C21D8/02 C22C38/58 B21B1/26 

FIELD: metallurgy.

SUBSTANCE: steel sheet thickness up to 50 mm contains, wt %: C 0.10-0.14, Si 0.16-0.30, Mn 1.35-1.60, Al 0.02-0.05, S not more than 0.005, P not more than 0.018, Ti 0.010 -0.025, Nb 0.025-0.040, V+Nb+Ti not more than 0.07, Cr+Ni+Cu not more than 0.3, N not more than 0.007, Fe and impurities the rest. At that Seq≤0.43% has ferrite and perlite microstructure, yield strength is at least 335 MPa, temporary resistance is at least 470 MPa, elongation is at least 22%, KV impact work at minus 50°C at least 34 J. When the sheet is produced, the continuously poured blank is heated to 1190-1210°C, conduct rough rolling at a starting temperature not lower than 950°C thickness of at least two thicknesses of the finished sheet, with relative reduction per pass of at least 10% for not less than 80% of the number of crimps in roughing, finishing rolling at a starting temperature based on Tst=(-1.05×h+860)±10°C, where h is the thickness of the sheet, mm, 1.05 is the empirical coefficient determined experimentally, °C/mm, and completed at a temperature of 820±10°C, after which the sheet is cooled in air.

EFFECT: ensuring weldability and increased impact performance at low temperatures.

2 cl, 3 tbl