汽车半轴用超低氧非调质钢洁净度研究

Investigation of Cleanliness of Non-Quench-and-Tempered Steel With Ultra-Low Oxygen Content for Automobile Semi-Axis

对EAF-LF-VD-CC工艺生产汽车半轴用非调质钢试验过程中钢水及铸坯洁净度变化规律进行了研究。为了将铸坯w(T[O])控制在0.001 0%以下,LF精炼渣碱度应该控制在4.0或更高,渣中w(FetO)+w(MnO)控制在1%以下,精炼过程中应控制吹氩量,避免渣中w(FetO)+w(MnO)升高;VD精炼过程应增加软吹氩时间以促进夹杂物上浮,喂入Si-Ca后应及时加入CaO防止渣碱度偏低,渣中w(SiO2)应控制在10%或以下;中间包应做好保护浇注,适当降低连铸过程中的拉坯速度,减轻并防止中间包注流区和浇注区钢水卷渣。

Cleanliness of non-quench-and-tempered steel with ultra-low oxygen content for automobile semi-axis, produced by EAF-LF-VD-CC process was investigated. It was found that several measures should be taken to produce billets with a total oxygen content below 0. 0010%. Firstly, the basicity of LF slag-ω（CaO）/ω（SiOz ） ratio-must be controlled at 4.0 or higher. As well, （FetO＋MnO） content in LF slag should be kept below 1% by control of bottom-blown argon flow rate to avoid the pick-up of it. Secondly, calcium oxide should be added during vacuum degassing to maintain a high basicity slag, with SiO2 lower than 10%. The time of argon blowing during vacuum degassing should be increased to promote the removal of inclusions from molten steel. Thirdly, reoxidization of the molten steel should be prohibited in the tundish as well as proper casting speed should be used to alleviate or even eliminate the entrapping of tundish slag.