高性能轴承钢真空自耗熔炼过程组织演变规律与控制研究

Evolution and Control of Bearing-Steel Microstructures in Vacuum Consumable Melting

通过Pro-CAST有限元软件模拟了高性能轴承钢真空自耗熔炼过程的温度场、熔池形貌和微观组织,研究了真空自耗铸锭组织演变规律,探究了温度场、熔池形貌对组织生长的影响。熔炼结束后,对真空自耗铸锭进行解剖酸洗以验证模拟结果。研究表明:模拟结果与实验结果吻合,铸锭组织形貌为贯穿铸锭中心的细长柱状晶,真空自耗铸锭的底部、边部和凝固末端有小面积等轴晶。柱状晶的生长带有明显的择优取向,底部柱状晶取向为垂直向上,中上部为斜向上。熔池深度越大,斜向上角度越小;熔池形貌对铸锭组织形貌影响显著,通过控制熔炼参数控制好熔池形貌能有效提高铸锭质量。

The evolution of the microstructures of the high performance bearing steel in vacuum consumable melting was mathematically modeled,theoretically analyzed in thermodynamics and crystal growth theories,numerically simulated in finite element method with software Pro-CAST,and experimentally evaluated. The influence of the melting conditions,including the temperature field and depth of cylindrical weld-pool,on the microstructures of the bearing steel ingot was investigated. The simulated results show that the vacuum consumable melting significantly improves the microstructures and textures of the ingot. For example,a narrow,long well-defined columnar crystal exists at the center along the axis of the ingot,whose preferential growth orientation depends on the pool＇s depth and vertical position,being vertically upward at the bottom but tilted a little in the upper half; and small equiaxedgrains were observed at the bottom,on the shank and at the top of the ingot. The simulated and experimental results were in good agreement.