Effects of cooling process on microstructure and #br# mechanical properties in a V-Ti bearing steel
LIU Xuhui1,2，LI Guanghui2，LIU Zhenyu1
(1. The State Key Laboratory of Rolling and Automation， Northeastern University， Shenyang 110819， Liaoning，
China；2. Technology Center， Hunan Valin Lianyuan Iron and Steel Co., Ltd.， Loudi 417000， Hunan， China)
Abstract：In order to obtain a larger increase in precipitation hardening，the effects of UFC final cooling temperature and second stage cooling rate on a VTi bearing steel were investigated using thermal simulation test. The results show that the microstructure and mechanical properties of the VTi bearing steel can be optimized significantly by controlling both UFC final cooling temperature and second stage cooling rate. The critical second stage cooling rates to obtain full ferrite microstructure have been estimated to be 1.0，1.0 and 0.2 ℃/s for the UFC final cooling temperatures of 750，700 and 650 ℃，respectively. At the second stage cooling rates of 0.2-1.0 ℃/s， the ferrite grain size can be refined from 10.5 to 8.4 μm by lowering UFC final cooling temperature from 750 to 650 ℃. For a higher second stage cooling rate of 5.0 ℃/s，the ferrite grain size can be refined from 10.5 to 5.1 μm. For the higher UFC final cooling temperatures of 750 and 700 ℃， the Vickers hardness can be enhanced by increasing second stage cooling rate，whereas for a lower UFC final cooling temperatures of 650 ℃，the Vickers hardness can be enhanced by lowering second stage cooling rate. Moreover，the Vickers hardness of the steel can reach 295HV.
刘旭辉，李光辉，刘振宇. 冷却路径对V-Ti微合金钢组织性能的影响[J]. 钢铁, 2019, 54(7): 77-82.
LIU Xuhui，LI Guanghui，LIU Zhenyu. Effects of cooling process on microstructure and #br# mechanical properties in a V-Ti bearing steel. Iron and Steel, 2019, 54(7): 77-82.
