Modification Effect and Mechanism of La-Ce on Inclusions in GCr15 Bearing Steel
In order to investigate the effect of Rare Earth La-Ce on the modification of inclusions in GCr15 bearing steel,a high-temperature tube furnace with a nominal capacity of 1 kg was used to smelt 6 heats of GCr15 bearing steel ingots with different La-Ce contents.Characterization methods such as optical microscopy and scanning electron microscopy were used,and the transformation law of inclusions in GCr15 steel at different La-Ce contents was studied using FactSage ther-modynamic software.The results show that the typical inclusions in GCr15 bearing steel without adding La-Ce are Al2O3 and MnS,and the addition of La-Ce will modify it to more complex Rare Earth inclusions.With the increase of La-Ce con-tent,the transformation law of inclusions in steel at 1 600 ℃ is Al2O3 → REAlO3 → RE2O3 → RE2O2S →RE2O2S+RExSy(RE is La、Ce).With the increase of La-Ce content,the density of inclusions and the average aspect ratio in the steel both decrease first and then increase.When the La-Ce content is 96×10-6,Al2O3 and MnS were both transformed into spherical RE2O2S·RExSy composite rare earth inclusions.The number of inclusions in the steel was at a low level and the overall morphology of the inclusions was well controlled.