| 摘要 |
PURPOSE:To produce a wire rod having high strength and toughness and having less fluctuations in mechanical properties, by cooling with water a medium or high carbon steel wire rod up to the temp. just above the Ms point after hot finish rolling, looping the wire rod and annealing the rod with blast cooling and heat retaining devices during conveying. CONSTITUTION:A medium or high carbon steel wire rod 4 of usually about 900- 1,000 deg.C right after the passage through final hot finishing rolls 2 is cooled forcibly down to the temp. range between the temp. at which martensite transformation initiates (Ms point) and the temp. (Ms+100 deg.C) to form mild supercooled austenite texture, in a water cooling device 6, whereafter the wire rod is developed like loops on a conveyor 10 by means of a loop layer 8. While the looped wire rod 4 is conveyed, the wire rod is cooled at >=20 deg.C/sec cooling rate with a blast cooling device 14A having a blower 12 to complete the martensite transformation, whereafter the wire rod is passed through a heat retaining device 16 so as to be tempered. The wire rod 4 provided with desired mechanical properties is passed through a blast cooling device 14B and is coiled with a coiler 18. |
