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中亚天然气X70管线钢对钢材的强度、低温冲击韧性和落锤撕裂试验具有很高的要求，因此所冶炼的钢水必须同时具有很低的硫、磷、氮含量以及比较低的碳含量。为此，首钢首秦钢铁公司采用“铁水脱硫－顶底复吹转炉－LF炉－RH精炼－板坯连铸”流程，通过冶炼工艺的改进和完善成功地开发了X70管线钢，钢中硫、磷、氮等元素平均含量分别达到了如下水平：S：18ppm、P：70ppm、N：41ppm，同时钢中碳含量也稳定在了0.055%左右。本文对X70管线钢冶炼过程中上述元素的控制进行了讨论。

The pipeline steel grade X70 used for Mid-Asia gas transportation project has very stringent requirements on its strength, toughness at low temperature and Drop Weight Tear Test(DWTT) values. Therefore phosphorus, sulfur, nitrogen and hydrogen contents in steel should be controlled as low as possible. At the same time low carbon concentrations with narrow ranges is also desired. At Shougang Shouqin steel plant X70 pipeline steel grade was successfully produced with the “Hot metal Desulphurization-BOF-LF-RH-CC” routine. The Carbon in steel is stabilized around 0.055% and the average content of sulfur, phosphor and nitrogen are 18ppm, 70ppm and 41ppm respectively. In the present paper the metallurgical technology for content control of above mentioned elements is discussed.