Effects of Rare Earth Element La on Inclusions and Tensile Strength of Clean Steel

In order to get hold of the effect of La on inclusions of the clean steel,SEM,EDS and ICP were used to study the shapes and sizes of inclusions and the tensile strength of the steel.The results show that with the increase of La content from 0 to 0.10% in the steel the La solution amount and its content in the inclusions increased from 0 to 0.022 6% and from 0 to 0.020 0%,respectively.The inclusions transformed obviously from silicate and aluminate into LaAlO3,LaS,La2O2S and LaxSy,and their shapes from irregular shape into regular sphericity.Their sizes were less than 3 μm.The content of La in inclusions hardness and tensile strength of the steel increased with the increase of La content.