关键词: 8620系齿轮钢, 轻压下, 点状裂纹法, 宏观偏析

Abstract: The thickness of the shell of the 300 mm × 340 mm continuous casting billet of 8620 series gear steel （/% 0.18 - 0.24C， 0.18 - 0.32Si， 0.65 - 1.0Mn， 0.45 - 0.55Cr， 0.50 - 0.80Ni， 0.15 - 0.25Mo， ≤ 0.025P， ≤0.020S） at the place of each tension leveler （point crack method） ， is calculated by using the point crack pressed on the solidifying front of the casting blank by tension leveler， and then the solid phase ratio of the center of the bloom is calculated by substituting the calibration model with the data， to design the pressure reduction . The total 4 tension levelers of 5 th，6 th，7 th and 8 th are used to press down， with pressure reduction 2 mm、3 mm、5 mm、4 mm respectively， and total pressure reduction is 14 mm.After experiment ， the carbon-sulfur analysis is carried out by drilling holes in the bloom and rolled material samples.The results show that， comparing to the cast billet without light pressure， the ratio of carbon segregation index 0.97-1.03 of gear steel 8620 CC bloom increases from original 83.5% to 94.2% ， and the ratio of carbon segregation index of rolled steel increases from original 91.5% to 98.8% ，in situ analysis density of macro structure test piece increase from 0.899 9 to 0.976 9， porocity decreases from 0.100 3 to 0.017 8， and the composition segregation and density of casting billet improve.

Key words: 8620 Series Gear Steel, Soft Reduction, Piont Crack Method, Macro-Segreation