大断面轴承钢棒材超快速冷却工业化试验

Industrial experiment of ultra-fast cooling for large-section bearing steel bar

针对国内某钢厂大断面轴承钢棒材连铸连轧后(棒材直径≥60 mm)先共析碳化物网状等级超标问题,通过对前期的研究工作进行归纳总结,在保证连铸连轧的基础上设置新型水冷系统并进行超快速冷却工业化试验,检验冷却到室温后棒材微观组织性能和先共析碳化物网状等级。试验结果表明:通过高温终轧后设定合理的超快速冷却工艺参数可以显著提高棒材表层以及芯部的冷却速率,抑制强碳化物形成元素的晶界处偏析。超快冷后棒材的室温微观组织均为片层珠光体。晶界处先共析碳化物的网状析出得到消除,仅在棒材芯部有少量碳化物呈弥散分布,碳化物网状等级符合行业标准。

Against to the problem of network carbide precipitation level beyond standard for large-section bearing steel bar which diameter greater than or equal to 60 mm after continuous casting and rolling, the ultra-fast cooling （UFC） industrial experiment was done by installing the new ultra-fast cooling devices. Microstructures and car bide network level of the bars were detected after cooling to room temperature. The experimental results show that cooling speeds of the surface and core of the bar increase significantly by setting reasonable ultra-fast cooling pa- rameters, so the segregation of carbide forming elements gathering in the grain boundary is suppressed. The sec- tion microstructure of the bar after UFC is larnellar pearlite at room temperature. Network carbide precipitating a- long grain boundary is eliminated and only a little of dispersion carbide distribute in the core of the bar. As a re- sult, the grade of network carbide reaches the professional standard.