STEEL WITH HIGH RUPTURE RESISTANCE AND PROCESS OF PRODUCTION THEREOF Russian patent published in 2003 - IPC

FIELD: steelmaking. SUBSTANCE: invention relates to production of steel for natural gas, crude oil, etc. transportation mains, which is characterized by high rupture resistance (about 900 MPa) and excellent impact elasticity throughout all its thickness, and also high level of properties in welded joints. Steal is preferably composed of, wt %: carbon 0.02-0.1, silicon no more than 0.6, manganese 0.2-1.7, nickel 0.2-1.2, niobium 0.01-0,1, titanium 0.005-0.03, aluminum no more than 0.1, nitrogen 0.001-0.006m copper 0-0.6, chromium 0-0.8, molybdenum 0-0.6, vanadium 0-0.1, boron 0-0.0025, and also calcium 0-0.006. Vs value determined from equation vs=C+(Mn.5)+5P-Ni/10-Mo/15+Cu/10 is within the range from 0.15 to 0.42. P and S, being among other impurities are contained in amounts not exceeding 0.015% and 0.003%, respectively. Size of carbide particles contained in steel does not exceed 5 mcm in longitudinal direction. EFFECT: improved performance characteristics. 18 cl, 9 tbl _