Abstract: The production process of tested bearing steel GCrl5 is 100t BOF- LF-RH-250mm x280mm bloom casting-φ70mm bar rolling. The effect of bloom casting rate 0.52〜0.58 m/min of bearing steel GCrl5 with casting parameters of mold cooling water rate 2530 L/min, liquid superheating extent 33~37℃ , secondary cooling water ratio 0.12 L/kg, M-EMS 530 A/2.5 Hz and F-EMS 400 A/3.0 Hz on bearing steel carbon segregation, shell thickness and end solidification position, and banded structure of Φ70 mm rolled bar has been studied by using the analysis and test methods including bloom cross section carbon segregation examination, nail shot test and optical microscope test Results show that with increasing casting rate the macro carbon segregation of bloom first decreases then increases, the end solidification position moves forward and the length of liquid core becomes longer, to control casting rate 0.55 m/min is available to decrease the bloom macro carbon segregation and the rating of banded structure of rolled products after spheroidizing annealing.

Key words: Fluctuation of Casting Rate, Casting Bloom, Bearing Steel GCr15, Internal Quality

摘要： 试验用GCr15轴承钢的生产工艺为100t BOF-LF-RH-250mm×280mm连铸坯-Φ70 mm轧材。用碳截面偏析检验、射钉试验及高倍检验等分析检测方法,研究了结晶器冷却水2530 L/min,钢水过热度33~37℃,二冷比水量0.12 L/kg,M-EMS 530 A/2.5 Hz,F-EMS 400 A/3.0 Hz参数下,GCr15轴承钢连铸坯拉速0.52~0.58m/min对连铸坯轴承钢碳偏析、坯壳厚度及末端凝固位置和Φ70mm轧材带状的影响。结果表明,随着连铸拉速的提升,铸坯的宏观碳偏析先呈现下降后呈现上升趋势,凝固末端位置后移,液相穴长度变长,拉速控制在0.55m/min,有利于降低铸坯的宏观碳偏析和轧材球化退火后的带状组织级别。

关键词: 拉速波动, 连铸方坯, GCr15轴承钢, 内部质量