| 摘要 |
PURPOSE:To make the titled wire material excellent in descaling property and workability, by hot-rolling a low-carbon steel piece or its cast piece into a large- sized wire material in the temperature range where two phases of alpha and gamma coexist, cooling it with water, coiling it into a tight coil and then forcedly cooling it. CONSTITUTION:A carbon steel piece having C content below 0.20wt% or its cast piece is heated in a temperature range above A1 transformation point +100 deg.C but below A3 transformation point +150 deg.C and hot-rolled into a wire material having a diameter exceeding 13mm. in the temperature range where two phases of alpha and gamma (ferrite and autenite) coexist. The rolled wire material 2 being fed from the final finish-rolling mill 1 is passed through a cooling guide pipe 3 and a space between pinch rolls 4 and then introduced into a coiling rotary drum 5. On this occassion, the wire material 2 is cooled to 800 deg.C or lower by introducing cooling water into the guide pipe 3. The drum 5 is then carried by a conveyer 6 and concurrently cooled to 300 deg.C at a cooling speed of 0.65-1 deg.C/sec by a large amount of high-pressure cold air from cooling hood arrangements. |
