The Research On Controlled Cooling Technology For Bearing Steel After Hot Rolling

As the economy develops in china, market needs for high carbon chromium bearing steel, represented by GCr15, increases rapidly, and the quality of the bearing steel products has been demanded higher especially in controlling the grade of net carbide. 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. So in this paper, according to the manufacturing conditions in blooming plant of Baoshan Iron &Steel Co., Ltd. Special Steel Branch, the present work is based on the manufacturing technique research of bar features with controlled cooling, The controlled cooling after hot-rolled of GCr15 bar was studied through experimental analysis and theoretical analysis. The mainly research contents and results of the present work are included as the following:(1) Based on the MMS-200 thermal simulation machine, completed thermal simulation experiments at final-pass temperatures of 980℃, and with different cooling rate after deformation. In combination with micro structure examination, the technique could be used to optimize cooling rate of GCr15 bearing steel after hot rolling so as to provide theoretical foundation and improve the quality.(2) The fast cooling temperature field was simulated by using of ANSYS software. The results were a good agreement with the real temperatures. By the simulation of the ribbed bars temperature in the center, in the half-center of radius and in the surface, it can be known that with the water unit now can control temperature to reduce network grade of carbide in large-cross-section bearing steel.(3) With Visual Basic and the secondary development tool APDL of ANSYS, developed the user-friendly numeric analysis system of GCrl5 temperature field in controlled cooling. Strengthen ANSYS process ability. The friendly, convenient and flexible human-computer interface is developed by Visual Basic foreground and the complicated and indigestible ANSYS command stream is encapsulated in background, and thus the system can improve the efficiency of GCr15 temperature field analysis greatly.(4) Combining simulation and experiment with practice, the optimization analysis thatΦ40～Φ60mm bearing steel cooling and rolling process is done, which will offer basic for the spot.