HOT-ROLLED STEEL STRIP FOR PRODUCTION OF FLEXIBLE PIPES FOR COIL TUBING AND METHOD FOR PRODUCTION THEREOF Russian patent published in 2025 - IPC C22C38/40 B21B1/22 B21B1/46 B21B3/02 

FIELD: performing operations.

SUBSTANCE: invention relates to production of hot-rolled steel strip. Cast iron is desulphurised till sulphur content in it is not more than 0.003%. Steel is melted in steel melting unit. Iron fraction is set as not less than 70% of metal charge weight, tapping of melting metal to steel ladle is performed during not less than 3.0 minutes. During out-of-furnace treatment steel is blown with neutral gas for at least 30 minutes with total consumption of at least 0.5 m³/ton of steel. Steel is poured to continuously cast billets with content of chemical components given in claim. Workpieces hot rolling is performed, during which beginning of hot finish rolling is set in temperature range 950-1100 °C, end of hot finish rolling is set in temperature range of 820-960 °C. Then, strip is cooled at rate of 5-25 °C/s to coiling temperature 510-650 °C.

EFFECT: obtaining a steel strip with tensile strength of not less than 550 MPa, yield strength of not less than 480 MPa, relative elongation of not less than 17%, hardness HRB of not more than 99, impact work KV at minus 60 °C not less than 17 J.

5 cl, 3 tbl