METHOD FOR MANUFACTURE OF HOT ROLLED STRIPS FOR TUBE SKELP Russian patent published in 2003 - IPC

FIELD: manufacture of rolled products. SUBSTANCE: method involves heating metal; rolling for producing strip of thickness not in the excess of 3.9 mm, with rolling temperature, total relative reduction value and rolling speed being regulated depending upon carbon equivalent value C_e; rolling in finishing stands of rolling mill in temperature range of (t₁-t₂), where: t₁ = 638×(C0,04e

+0,6) C; t₂ = 0,9t₁ at t₁≤975^°C;t₂ = 0,91t₁+15^°C at t₁ = 980-995^°C and t₂ = 0,93t₁+15^°C at t₁≥1000^°C, with total relative reduction value being ε₁≥9,35/(C_e+0,03),%. When temperature is less than t₂, but higher than 700 C, rolling process is effected at total relative reduction value of ε₂≥80/ε^0,24,% for for C_e = 0,29-0,40;ε₂≥200/ε^0,6,% at rolling speed C_e = 0,41-0,46 and ε₂≥64,2/ε^0,3,% at inlet end of finishing stand. Method further involves cooling at regulated rates depending upon C_e>0,46 in two stages: at first stage in temperature range of (Tf-t), where Tf is temperature at final rolling step, C; V_r≥(0,65/C_e)+0,05,m/s at cooling rate of c_e for t = 586/(C_e+0,2)^0,1,^°C and W₁≥0,1065(T_k/100)^1,5,^°C for C_e≥0,33. Cooling at second stage is effected in temperature range of (t₁-t₂), where: t>t₁>t-(8-12^°C) and are effected at cooling rate of W₂≥0,058(T_k/100)^1,7,^°C for C_e<0,26 and W₂≥(T_k/100)/10C_e+0,1)+(T_k/800)+1,95^°C for C_e≥0,26. EFFECT: improved quality of ready rolled product with uniform mechanical properties along the entire strip length due to providing homogeneous finely dispersed steel structure. 2 cl