STEEL MATERIAL FOR HIGH-STRENGTH STEEL PIPE WITH LOW RATIO OF YIELD TO STRENGTH, HAVING EXCELLENT LOW TEMPERATURE IMPACT VISCOSITY, AND METHOD FOR ITS PRODUCTION Russian patent published in 2021 - IPC C22C38/58 C21D8/02 C21D7/13 

FIELD: metallurgy.

SUBSTANCE: invention relates to the field of metallurgy, namely to a steel material used for the manufacture of high-strength steel pipes. The material contains, in wt%: 0.03-0.065 C, 0.05-0.3 Si, 1.7-2.2 Mn, 0.01-0.04 Al, 0.005-0.025 Ti, 0.008 or less N, 0.08-0.12 Nb, 0.02 or less P, 0.002 or less S, 0.05-0.3 Cr, 0.4-0.9 Ni, 0.3-0.5 Mo, 0.05-0.3 Cu, 0.0005-0.006 Ca, 0.001-0.04 V, the rest is Fe and inevitable impurities. The number of inclusions of TiC, NbC and (Ti, Nb) C having an average diameter of 20 nm or less per unit of sectional area of the steel material is 6.5∙10⁹/мм² or more.

EFFECT: steel material has excellent low temperature toughness and low yield strength to tensile strength ratio.

17 cl, 5 tbl