8620系齿轮钢300 mm x360 mm连铸坯宏观偏析改善的工艺实践

8620齿轮钢(/%:0. 18～0.22C,0. 17～0.26Si,0.70～0.90Mn,≤0.025P,0. 15～0.23S, 0.40～0.60Cr,0.40～0.70Ni,0.15～0.25Mo)300 mm×360 mm坯连铸的中间包钢水过热度为20～30℃,拉速为0.5～0. 6 m/min,通过钻孔分析、射钉试验、原位分析和铸坯低倍组织分析,研究了电磁搅拌参数M-EMS(100～200) A,(2.0～2.2)Hz,F-EMS(150～200)A,8 Hz]和二冷水参数(一段28 L/min,二段38～45.6L/min,三段19.2～24L/min)对连铸坯C、S偏析的影响。通过采用优化工艺参数-二冷一段28 L/min,二段45. 6 L/min,三段19. 2 L/min和电磁搅拌M-EMS 150 A,2. 2 Hz,F-EMS 200 A,8 Hz,8620系齿轮钢连铸坯偏析指数0. 98～1.05的比例由原30%提高至92.8%。

Process Practice on Improvement of 300 mm x 360 mm Casting Bloom Macro-Segregation of 8620 Series Gear Steel

The superheating extent of liquid of 8620 gear steel (/% : 0. 18 ?0. 22C, 0. 17 ~ 0. 26Si, 0. 70 ~ 0.90Mn, ≤ 0.025P, 0.15 ~0.23S, 0.40 ~ 0.60Cr, 0.40 ~0.70Ni, 0.15 ?0.25Mo) for casting 300 mm x 360 mm bloom is 20 ~30 ℃ and the casting speed is 0. 5 ~0. 6 m/min, and by bloom drilling analysis, pin-shooting test, original position analysis and bloom macrostructure analysis the effect of electromagnetic stirring parameters M-EMS (100 - 200) A, (2.0 ~ 2.2) Hz, F-EMS ( 150 ~ 200) A, 8 Hz] and secondary cooling water parameters (Ⅰ- zone 28 L/min, Ⅱ - zone 38 ~45.6 L/min and Ⅲ- zone 19. 2 ~24 L/min) on C and S segregation in bloom has been studied. With using optimized process parameters- secondary cooling water Ⅰ- zone 28 L/min, Ⅱ - zone 45.6 L/min and Ⅲ- zone 19.2 L/min, and electromagnetic stirring M-EMS 150 A, 2. 2 Hz, F-EMS 200 A, 8 Hz, the ratio casting bloom of 8620 series gear steel with segregation index 0.98 ~ 1.05 increases to 92.8% from original 30%.