Regular Article

Effect of CeO₂ addition in the slag on inclusions of FGH96 superalloy during electroslag remelting

Beijing Advanced Innovation Center for Materials Genome Engineering, Institute for Advanced Materials and Technology, University of Science and Technology Beijing, Beijing 100083, PR China

^* e-mails: zlin@ustb.edu.cn; quxh@ustb.edu.cn

Received: 7 January 2020
Accepted: 23 June 2020

Abstract

The FGH96 superalloy was electroslag remelted by utilizing CeO₂ containing slag. CeO₂/Al₂O₃ ratio and atmosphere are found to be the main factors that control the oxide inclusion contents during electroslag remelting (ESR). The reaction between CeO₂ in the molten slag and Al in the molten alloy leads to the increased dissolved Ce in the molten alloy, which is effective to remove oxide inclusions. Dissolved Ce reacts with MgO in the inclusions, leading to the transformation of Al₂O₃–MgO inclusion in the electrode to Al₂O₃–MgO–Ce₂O₃ and Al₂O₃–Ce₂O₃ inclusions in the ESR ingot. In case of low CeO₂/Al₂O₃ ratio of 0.263, oxygen content decreases to as low as 8 ppm after ESR under vacuum, and the number density of oxide inclusion decreased by an order of magnitude in comparison to the electrode. In case of high CeO₂/Al₂O₃ ratio of 5.0, oxygen content decreases further to 6 ppm no matter what the condition is.