0Cr13C不锈钢线材表面混晶缺陷及工艺改进

Mixed Crystal Surface Defect of Wire Rod of Stainless Steel 0Cr13C and Process Improvement

0Cr13C不锈钢Ф5.5~15mm线材的生产工艺为60 t中频感应炉-90 t AOD-LF-180 mm×180 mm坯连铸-连轧。通过光学和扫描电子显微镜对表面"裸晶"缺陷0Cr13C钢线材(/%:0.021C,0.32Si,0.35Mn,0.030P,0.004S,12.10Cr)的分析,得出该缺陷源于混晶:(a)连铸钢水过热度大,二冷水量小,造成连铸坯中铁素体枝晶间距较大,(b)加热炉温度过高,使钢中铁素体晶粒异常长大。通过将中间包钢水过热度从50℃降至30℃,拉速由1.2 m/min降至1.0m/min,电磁搅拌由150 A-3 Hz提高至280 A-6 Hz,二冷水量由0.19 L/kg增加至0.33 L/kg,以及将铸坯加热温度由1080~1130℃降至1020℃等工艺措施,避免了线材表面"裸晶"缺陷。

The production process of Ф5. 5~15 mm wire rod of stainless steel 0Cr13C is 60 t medium frequency induction furnace-90 t AOD-LF-180 mm x 180 mm billet casting-continuous rolling. The surface ＂exposed crystal＂ defect of wire rod of steel 0Cr13C（/% ： 0. 021 C, 0. 32 Si, 0. 35 Mn, 0. 030 P, 0. 004 S, 12. 10 Cr） is analyzed by optical and scanning electron microscope to get the defects take its source at mixed crystal due to（ a） large overheating extent of casting liquid and small secondary cooling water rate led to larger dendritic inter-planar spacing of ferrite in casting billet and（b）higher temperature in heating furnace led to abnormal growth of ferrite grains in steel. With the process measures including decreasing overheating extent of liquid in tundish to 30 ℃ from 50 ℃, decreasing casting speed of billet to 1. 0 m/min from original 1. 2 m/min, improving electromagnetic stirring to 280 A-6 Hz from original 150 A-3 Hz, increasing secondary water cooling rate to 0. 33 L/kg from 0. 19 L/kg and reducing casting billet heating temperature to 1 020℃ from original 1 080 ~1130 ℃, the surface ＂exposed crystal＂ defects of wire rod are avoided.