中文摘要：

为开发高级别管线钢精炼技术，用真空感应炉在800Pa的Ar气氛中熔化3．3kg工业纯铁，用合金元素把其成分调整成0．05C-0．3Si-2．0Mn（质量分数／％，下同）的管线钢后，加入Ce元素于1873K下精炼，制备了4种不同Ce含量的钢样。用检测结果，研究分析了0．05C-0．3Si-2．0Mn-xCe系钢液的洁净度和夹杂物变性行为及其作用机理。结果表明：[Ce]在0．0052％-0．0374％时，[0]，[S]随Ece]含量的增加而显著降低，分别达到0．0008％，0．0010％；钢材的屈强比、伸长率和冲击功等也随[Ce]含量的增加呈先增加后减小的趋势，其峰值分别达到92．9％，24．3％，276J。其原因是[Ce]把13μm带棱角的SiO2-MnS夹杂物、原长条状、大体积的MnS夹杂物转变为1μm左右、甚至纳米级球形稀土硫氧夹杂物。

英文摘要：

In order to develop high-level pipeline steel refining technology, the industrial pure iron and some elements were melted by vacuum induction furnace at 800Pa in Ar atmosphere, and refining by adding Ce element at 1873K, the 0.05 C-0.3 Si-2.0Mn（mass fraction/%） of four different Ce contents were obtained. The cleanliness of 0.05C-0.3Si-2.0Mn-xCe series liquid steel, modification behavior of inclusion and its mechanism were analyzed and discussed. The results indicated that when [Ce] con- tent was 0. 0052%-0. 0374%, with Ce content increasing, [O] and IS] reduced remarkably, reaching to 0. 0008% and 0. 0010% respectively. With Ce content increasing,the yield ratio, elongation and im- pact energy of steel first increase then decrease, reaching to 92.9%, 24.3%, 276J respectively. The reason is that the angular inclusions of SiO2-MnS, strip shape and large volume inclusion of MnS were changed into about μm, even nanometer scale spherical-shape inclusion of rare earth sulfur oxide.