| 摘要 |
PURPOSE:To prevent propagation of crack by applying compressive residual stress to both surface and inside of roll, by adjusting the cooling temperature of hardening after rolling Cr-Mo-V steel into roll form. CONSTITUTION:Cr-Mo-V steel containing C by 0.4-0.6%, Cr by 2.5-5%, Mo by 0.5-1.5%, V by <0.5%, Si by <1.5%, and Mn by <1.5% is processed to obtain a roll for hot rolling. This roll is uniformly heated to hardening temperature of 1000 deg.C+ or -50 deg.C, and is colled at a relatively high cooling speed of 500-1000 deg.C/hour to about 500 deg.C lower than the temperature of causing perlite transformation. Holding this temperature for a while, the temperature in the center of the roll is made equal to that of the surface. Cooling slowly again at a rate of 10-20 deg.C/hour, the surface of the roll is transformed to bainite, and compressive residual stress is applied to the surface and inside of the roll by expanding them. |
