轴承钢中TiN夹杂物的控制研究

Control of titanium nitride in bearing steel

研究了轴承钢中TiN夹杂物的形成热力学,以及钢中Ti和N的控制理论,并在某钢厂进行了GCr15轴承钢的生产实验.结果表明,在凝固过程中钢中Ti或N的含量越高,TiN夹杂物开始析出温度就越高,析出物的尺寸就越大;使用低Ti合金原料能够有效降低钢中的Ti含量;采用低Ti铁水,初炼渣中的TiO2降到1.0%以下,能有效控制钢水中的Ti含量;采用低钛合成渣过程回钛量显著减少,钢中Ti含量由原来的37×10-6下降至30×10-6;优化改进精炼工艺和大包保护浇铸可以降低钢中N含量为33×10-6;降低凝固偏析,能降低TiN夹杂析出.

The formation thermodynamics of the existed TiN inclusion and the control theory of titanium and nitrogen in bearing steel were studied. Then based on the theoretic calculation results,the industrial trials of GCr15 bearing steel were carried out in a steel plant. The results showed that the higher the titanium or nitrogen content in steel is,the higher the precipitation temperature of TiN,and the bigger the size of precipitates;the use of low-Ti alloy materials can effectively reduce the Ti content;using low-Ti molten iron and reducing the TiO2 content to less than 1.0% in furnace slag can control the Ti content effectively. The use of low-titanium synthetic slag can make Ti content of the steel drop from the original 37×10-6 to 30×10-6. Optimized and improved refining processes protective casting process can reduce the N content of 33×10-6. With the degree of solidification segregation decreases,the precipitation of TiN inclusion is reduced.