Study on the modification of inclusions by Ca treatment in GCr18Mo bearing steel
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The effect of Ca treatment on the modification of inclusions in Al-killed GCr18Mo bearing steel was studied and a thermodynamic and kinetic model was established. The experimental results showed that oxygen content in the steel could be reduced from 120 μg/g to the range 5.5–21.6 μg/g by Al-Ca complex deoxidization at 1 873 K. An appropriate increase in Ca/Al mass ratio is beneficial to reduce the total oxygen content in steel. When the content of dissolved aluminum was in the range of 0.03%–0.3%, with the increase of Ca/Al mass ratio from 0.8–1.6 to 2.4–3.2, the number of inclusions per unit area significantly reduced. In addition, the main types of inclusions were modified from large-sized Al2O3 clusters to plastic or semi-plastic liquid phase calcium aluminates. The experimental results matched well with the thermodynamic analysis.
KeywordsGCr18Mo bearing steel Ca treatment Inclusion modification Deoxidization Thermodynamics
This study was financially supported by the Shanghai University and the Joint Funds of the National Natural Science Foundation of China (Grant No. U1560202).
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