镧对16Mn钢中夹杂物和组织的影响

Effect of lanthanum on inclusions and microstructure of 16Mn steel

在高温钼丝炉内向16Mn钢中加入不同含量镧进行脱氧。利用SEM、EDS和OM测试并研究La含量对钢中夹杂物的成分、大小分布及试验钢组织的影响,并探讨了钢中含镧夹杂物诱发晶内针状铁素体形核机制。结果表明,随钢中镧含量增加,夹杂物依次转变为LaAlO3、La2O2S和La2S3。试样经镧处理后,钢液在1600℃时保温180 s,夹杂物最为细小且弥散。钢中晶内铁素体含量随镧含量增加先增大后减小,最佳镧含量约为0.014%(质量分数)。钢中含镧夹杂物周围形成贫Mn区,促进晶内针状铁素体形核。

Deoxidation experiments of 16Mn steel were carried out by adding different content of lanthanum in a high temperature molybdenum wire furnace.The component,size and distribution of inclusions in the steel and the change of microstructure were studied by SEM,EDS and OM.Meanwhile,the nucleation mechanism of intragranular acicular ferrite which was induced by the lanthanum-containing inclusions was also explored.The results show that the inclusions are in turn transformed with increasing La as follows,LaAlO3,La2O2S and La2S3.The inclusion in the steel treated by La exhibits the finest distribution after holding for 180 s at 1600 ℃.The percentage of intragranular ferrite increases and then decreases with increasing of La and the optimum content of La is about 0.014%( mass fraction).The Mn depleted zone around the inclusions is obtained which is effective to the nucleation of intragranular acicular ferrite( IGF).