Abstract: By metallographic microscope, electron microscope etc. analyzing, it is obtained that surface serious decarburization of the C70S6 steel surface seriously causes the connecting rod expansion-broken bits dropping out, and internal quality defects. By optimizing the content of Al, V, and P, the ferrite constituent in steel decreases from orignial 5. 5% 〜8. 6% to 2. 7% 〜4. 8% ,and by using measures including continuous casting superheat reduced from≤35 ℃. to 30 ℃，casting speed reduced from 0. 80 ~0. 90 m/min to 0. 65 ~ 0. 75 m/min, electromagnetic stirring current at the end increased from 200 A to 300 A； coating the cast billet before rolling, air-fuel ratio in the high temperature section of the heating furnace reduced from 0. 7 ~ 0. 8 to 0. 5 ~ 0. 6, heating temperature increased to 1 200 ~ 1 250 °C ； and increasing cooling rate after rolling, the segregation of C in the center of the C70S6 steel is reduced to 0. 99 ~ 1. 04, the depth of the surface decarburization layer is ≤ 0.50% d, the grain size rating is 5. 5 ~ 6. 0, and the ferrite content is ≤5.0% , successfully solved the problem of bits dropping in batches of connecting rods.

摘要： 采用金相显微镜、电子显微镜等分析得出,C70S6钢表面严重脱碳以及内部质量缺陷均会造成连杆胀断掉屑,通过优化Al、V、P含量,钢中铁素体含量由原5.5%～8.6%降至2.7%～4.8%;连铸过热度由≤35℃降至≤30℃,拉速由0.80～0.90 m/min降至0.65～0.75 m/min,末端电磁搅拌电流由200 A提高至300 A;轧制前铸坯涂涂料,加热炉加热时高温段空燃比由0.7～0.8降至0.5～0.6,加热温度提高至1 200～1 250℃;并采用提高轧后冷速等措施后,C70S6钢中心C偏析降为0.99～1.04,表面脱碳层深度≤0.50%d,晶粒度5.5～6.0级,铁素体含量≤5.0%,成功解决了连杆批量掉屑质量问题。