PIPELINE STEEL WITH BOTH HIC RESISTANCE AND HIGH DEFORMATION RESISTANCE AND METHOD FOR ITS MANUFACTURING Russian patent published in 2023 - IPC C22C38/58 C21D8/02 

FIELD: metallurgy.

SUBSTANCE: pipeline steel used for the transportation of oil and natural gas. Pipeline steel has the following composition: C: 0.015–0.039%, Si: 0.15–0.35%, Mn: 1.6–1.9%, S: ≤ 0.002%, P: ≤ 0.012%, Al: 0.02–0.045%, Cr: 0.15–0.35%, 0.05≤ Nb + V + Ti≤ 0.1%, Nb, V and Ti are not equal to 0, Ni: 0.15–0.50%, Cu: 0.01–0.25%, Ca: ≤ 0.002%, N: ≤ 0.0046%, Mo: 0.01–0.20%, the rest is Fe and unavoidable impurities. The transverse yield strength is Rt0.5 490-550 MPa, the transverse tensile strength Rm ≥ 710 MPa, transverse ratio of yield strength to tensile strength Rt0.5/Rm ≤ 0.78, Charpy impact strength at -20°C greater than or equal to 350 J, drop shear area at -20°C is SA% ≥ 90%, longitudinal yield strength 460-530 MPa, longitudinal tensile strength greater than or equal to 690 MPa, longitudinal uniform elongation Uel ≥ 11%, the longitudinal ratio of yield strength to tensile strength is less than or equal to 0.77, and the longitudinal stress ratio is Rt1.5/Rt0.5≥1.18, Rt2.0/Rt1.0≥1.

EFFECT: high resistance of pipeline steel to hydrogen cracking and deformation resistance.

4 cl, 2 dwg, 1 tbl