Abstract: The distribution of C,Si,Mn and Cr elements in cross sections of Φ450 mm continuous casting round billet and Φ130 mm round steel of high hardenability bearing steel GCr15SiMn was analyzed by original position statistic distribution analysis(OPA)and borehole chemical analysis.The contact fatigue life of the material was tested by the thrust plate con-  tact fatigue testing machine.The results show that the segregation tendency of C element in bearing steel GCr15SiMn continuous casting round billet is large,and it is easy to produce center positive segregation,while the segregation tendency of Cr,Si and Mn element is small.The central carbon segregation in casting bloom was improved by adopting stable low superheat casting and three-stage strong electromagnetic stirring.After(1240±20)℃×5 h high temperature diffusion and large deformation rolling with primary pass deformation ≥90 mm,the carbon segregation of φ130 mm round steel can be further improved. The rated contact fatigue life L₁₀ of the test steel under 5.3GPa high stress load reaches 3.58×10⁶  times,which is close to the level of ESR steel.

Key words: Round Billet Continuous Casting;High Hardenability Bearing Steel, GCr15SiMn;Composition Segregation, Contact Fatigue Life

摘要： 利用金属原位分析技术和钻孔化学分析方法对高淬透性轴承钢GCr15SiMn的Φ450 mm连铸圆坯和Φ130 mm圆钢的C、Si、Mn、Cr元素横截面的分布情况进行分析。采用推力片式接触疲劳试验机进行了材料的接触疲劳寿命测试。结果表明：GCr15SiMn连铸圆坯C元素的偏析倾向较大，易产生中心正偏析，而Cr、Si、Mn元素的偏析倾向较小。通过采取稳定低过热度浇铸、三段强电磁搅拌等措施，铸坯的中心碳偏析得以改善。采用(1240±20)℃×5 h高温扩散、初轧首道次变形量≥90 mm大变形轧制的Φ130 mm圆钢的碳偏析可以得到进一步的改善，试验钢在5.3GPa高应力负载下的接触疲劳额定寿命L₁₀达到3.58×10⁶次，接近电渣重熔钢的水平。

关键词: 圆坯连铸；高淬透性轴承钢；GCr15SiMn, 成分偏析；接触疲劳寿命