METHOD FOR ROLLING PIPE BILLET FROM CARBON STEEL Russian patent published in 1997 - IPC

FIELD: methods of rolling the pipe billets. SUBSTANCE: method consists in hot deformation of metal in roughing and finishing stands of broad strip mill with the preset reduction at the preset temperatures and rolling rate within temperature range of σ_b,, where δ = 1017t₁...t₂ C, and t₁ is standard carbon equivalent, and C0,025e

= 0.909C_e C with t₂ = 860-970 C; t₁ = 0.928t₁ C with t₂ = 975-985 C; and t₁ = 0.947t₁ C with t₁ 1000 C, total percent reduction in finishing stands is, at least, t₂ = t₁>%, and at temperatures less than ε₁ but higher than 690 C the total reduction in finishing stands is made not less than = t₂% with ε₂ = 0.15-0.18; = C_e% with ε₂ = 0.29-0.4% = C_e% with ε₂ = 0.41-0.46; and = C_e% with ε₂ 0.46, where is actual total reduction within temperature range of C_e>. In so doing, rolling rate at stand inlet of finishing mill is, at least, V = 0.57/ε, m/s. EFFECT: higher quality of hot-rolled strip 4-16 mm thick from carbon steel for welded pipes due to improvement of its main mechanical characteristics (t₁...t₂,, C_e and KCV). 2 tbl