Controlled Cooling Of Big Section Bearing Steel Bar

During the process of controlled cooling of GCr15 bearing steel after rolling, the secondary carbide precipitation from grain boundary of austenite by the way of network carbide, which has a great influence to the using life of bearing. Therefore, it is an important problem for plant to settle about how to decrease the level of network carbide, improve the quality of bearing steel and decrease the cost. The paper performed study for big section bearing steel GCrl5 above φ42 of roughing mill plant of DTSTEEL.COM. The results indicated that:1.The CCT curves of GCr15 bearing steel were measured at the fishing rolling temperature of 8501 and 900℃ by Gleeble 3800.2.The thermal force test indicate that network carbide can be eliminated at the cooling speed is 5℃ per second at the final rolling temperature of 900℃, and network carbide can be eliminated at the cooling speed of 3℃ per second and final rolling temperature of 850℃.3. The simple water cooling facility is developed in the laboratory and the temperature fall curve of bearing steel with different ordinance at the different cooling rate is measured, the research shown that it has the obvious different between the big section bearing steel and the small section bearing steel.4. The optimization analysis of cooling process is done using the computational simulation associate with the various cooling process using in the field engineering. The conclusion which has the reference significance to field operating is put forward. The average cooling speed over 3℃per second for center will be entirety controlled and realized to inhibit the precipitation of network carbide by reasonable cooling intensity and cooling system for columned steel underφ60mm. But it should be difficult to operate in the field for columned steel aboveφ60mm.