Abstract: The production flowsheet of Ф6.5~20mm coil of cold-heading steel SWRCH35K is 120t LD-LF-180mmx180mm billet casting-rolling. The effect of composition, structure, surface quality of casting billet, inclusions in steel and rolling process on cold-heading properties of steel SWRCH35K (/%: 0.35~0.37C, 0.11~0.14Si, 0.71~0.72Mn, 0. 016~0.023P, 0.005~0.007S, 0.023 ~0.030Alt) has been analyzed to get the main reasons to cause coldheading cracks are cold-heading steel coil surface crack defects and near surface large scale inclusions. By using the measures including increasing amount of pre-deoxidizing aluminium pig in LD tapping from 120~150kg to 160~180kg, increasing LF end slag basicity from 3.0 to 3.5 and decreasing ( FeO+MnO) from ≤1.5% to ≤1.2% , decreasing supperheating extent of liquid from 20~40℃ to 20~35°C and increasing finish rolling temperature and finishing temperature respectively from 940°C and 860℃ to 950℃ and 880℃，the cold-heading cracking rate of steel decreases from 18.60% to 5.80%.

摘要： Ф6.5~20mm SWRCH35K冷镦钢盘条的生产流程为120t LD-LF-180mm×180mm方坯连铸-轧制。分析了SWRCH35K钢（/%:0.35~0.37C,0.11~0.14Si,0.71~0.72Mn,0.016~0.023P,0.005~0.007S,0.023~0.030Alt）的成分、组织、铸坯表面质量、钢中夹杂物、轧制工艺对该钢冷镦性能的影响,得出冷镦钢盘条裂纹等表面缺陷和近表面大型夹杂物是引起冷镦开裂的主要原因。通过LD出钢预脱氧铝块从120~150kg增加至160~180kg,LF终渣碱度从3.0提高至3.5,（FeO+MnO）从≤1.5%降至≤1.2%,过热度从20~40℃降至20~35℃,精轧温度和终轧温度分别从940℃和860℃提高至950℃和880℃等工艺措施,使该钢冷镦开裂率由18.60%降至5.80%。

关键词: 120tLD-LF-CC-轧制流程, SWRCH35K钢, 冷锹开裂, 分析, 工艺优化