稀土La及冷却速度对EH36船板钢晶内铁素体形成的影响

Effect of La and cooling rate on intragranular ferrite formation in EH36 shipbuilding steel

采用光学显微镜、带能谱的扫面电子显微镜等分析手段观察了稀土La和冷却速度对EH36船板钢晶内铁素体形成的影响。结果表明:添加0.015%La后,EH36船板钢中形成了大量细小、弥散分布的La_2O_2S夹杂物,尺寸约为2μm,错配度计算表明,La_2O_2S能够作为有效的晶内铁素体形核核心,显著促进晶内铁素体的形核,细化钢的显微组织。在试验3种冷速下(空冷、风冷、水冷),添加0.015%La的钢中,随着冷却速度的增大,晶内针状铁素体的含量不断增加;水冷条件下,晶内针状铁素体形核效果最好。

Effect of La and cooling rate on intragranular ferrite formation in EH36 shipbuilding steel were investigated by optical microscopy and scanning electron microscopy coupled to an energy dispersive X-ray spectrometer. The results show that a large number of finely dispersed La_2O_2 S inclusions form in the steel with addition of 0. 015% La,the size of which is approximately 2 μm. Based on the theory of lattice misfit,La_2O_2 S could serve as the effective core of intragranular ferrite,significantly improve the intragranular ferrite nucleation,and refine the microstructure of steel. Under three kinds of cooling rate（ air cooling,air-blown cooling,water cooling） in this experiment,with the increase of cooling rate,the amount of intragranular ferrite in the steel treated by 0. 015% La increases,moreover,the effect of water cooling is the best for intragranular ferrite formation.