HOT-ROLLED STEEL SHEET FOR COILED TUBING Russian patent published in 2020 - IPC C22C38/58 C22C38/50 B21C37/08 C21D9/08 C21D9/46 C21D9/50 

FIELD: metallurgy.

SUBSTANCE: invention relates to metallurgy, particularly, to hot-rolled steel sheet used for production of continuous flexible pipes (coiled tubing). Hot-rolled sheet has composition containing, wt.%: C more than 0.10 to 0.16; Si 0.1–0.5; Mn 1.6–2.5; P 0.02 or less; S 0.005 or less; Al 0.01–0.07; Cr more than 0.5 to 1.5; Cu 0.1–0.5; Ni 0.1–0.3; Mo 0.1–0.3; Nb 0.01–0.05; V 0.01–0.10; Ti from 0.005 to 0.05; N 0.005 or less; rest are Fe and unavoidable impurities. Sheet has microstructure containing 3–20 vol% martensite, 10 vol% or less residual austenite, rest is bainite.

EFFECT: produced hot-rolled sheets have yield point of 600 MPa or more, ultimate tensile strength of 950 MPa or more, uniform relative elongation of 7 % or more and manufacturability required for profiling, without need to perform hardening of solid pipe and repeated heating-tempering after electric welding and heat treatment of solid pipes.

1 cl, 2 tbl