中文摘要：

对不同氧含量的16Mn钢进行了La处理，观察实验钢中夹杂物和组织的变化。利用带有能谱仪的扫描电镜和光学显微镜研究了实验钢中夹杂物种类、大小分布及实验钢铸态的组织，同时对夹杂物诱导晶内铁素体形核机制进行了分析。结果表明：随着氧含量的增加，试样中夹杂物主要为LaAlO3和La2O2S复合夹杂及其各自单独夹杂物。在实验条件下，随着氧含量的增加，试样中晶内针状铁素体含量逐渐减少，有利于晶内针状铁素体生成的最佳氧含量约为45×10^-6错配度计算表明，所有的镧氧化物均有形核能力，而La2O2S夹杂形核能力比其他更好。

英文摘要：

The La treatment of 16Mn steel with different oxygen contents was carried out. The changes of inclusions and microstructure of the experimental steel were observed. The type, size and distribution of inclusions in the steel and its microstructure in casting for the experiment steel were studied by SEM-EDS and optical microscopy. Meanwhile, nucleation mechanism of inclusions inducing intragranular ferrite was analyzed. The results show that with the increase of oxygen contents, inclusions in the samples are mainly LaAlO3 and La2O2S composite inclusions and their respectively separate inclusions. Under the experimental condition, with the increase of the oxygen contents, in the sample intragranular ferrite content drops gradually and the optimal oxygen content to produce the intragranular ferrite is about 45 ×10-6. The mismatch degree calculation shows that all the oxides of lanthanum have the capability of nucleation, and La202S inclusions have better nuclear capability than others.