X70管线钢头坯质量的研究

Study on quality of first slab for X70 pipeline steel

针对某钢厂生产的X70管线钢,采用综合分析的方法,对头坯中的T.O、N、显微夹杂物、大型夹杂物以及皮下气泡进行了研究。研究结果表明:头坯中w(T.O)、w(N)稳定但较高,显微夹杂物数量平均为2.28个/mm2,大型夹杂物平均约含2.0 mg/10 kg,50%的显微夹杂物尺寸小于3μm。但钢中含有较多Al2O3与MnS复合夹杂,夹杂物变性效果较差,皮下气泡率较高,需进一步提高铸坯质量。

Aiming at slab of X70 pipeline steel,total oxygen content,nitrogen content,micro inclusions,large inclusions and skin pinhole in the first slab were studied by comprehensive analyses.The results showed that total oxygen content and nitrogen content were higher but steady,50% of micro inclusions was below 3μm in size and the content was 2.28 per mm2,the content of large inclusions was 2.0mg per 10kg.It is showed that the cleanliness of steel is high enough but there are a large amount of Al2O3 and MnS compound inclusions,which affects the modification and results in the high rate of skin pinhole.Therefore,further improvement of slab quality is needed.