Effect of O,S and Ce Contents on Ce2O3 and Ce2O2S Inclusions in U71MnG Steel
In our country,the large-scale production of rare earth steel has not been achieved mainly due to insufficient understanding of the interaction between rare earth and impurity elements such as O and S in steel.Considering the lack of quantitative analysis of the effect of Ce,O,and S contents on rare earth inclu-sions in steel,FactSage 7.1 software was used to investigate the interaction between different contents of O,S,and Ce in U71MnG steel,as well as their effects on the precipitation of Ce2O2S and Ce2O3 inclusions.Thermodynamic calculation results show that in the composition system of U71MnG steel,the precipitati-on of Ce2O3 increases at first and then decreases with the increasing Ce content,and reaches the peak at the ratio of mo/mce of approximately 1/7.4.The formation of Ce2O2S requires the joint action of O,S,and Ce,and the precipitation of Ce2O2S reaches the peak at the ratio of mo+s/mCe of approximately 1/3.7.SEM images of steel inclusions and statistical results of the number of inclusion particles show that the number of Ce2O3 and Ce2O2S inclusions in the test steel with a Ce content of 0.024％is higher than that in the test steel with a Ce content of 0.016％.And the laws of inclusion precipitation in steel are consistent with ther-modvnamicallv calculated results.
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