Effect of CeO<sub>2</sub> addition in the slag on inclusions of FGH96 superalloy during electroslag remelting
Xiaoyong Gao, Lin Zhang, Xuanhui Qu, Yifeng Luan, Xiaowei Chen
Abstract
The FGH96 superalloy was electroslag remelted by utilizing CeO 2 containing slag. CeO 2 /Al 2 O 3 ratio and atmosphere are found to be the main factors that control the oxide inclusion contents during electroslag remelting (ESR). The reaction between CeO 2 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 Al 2 O 3 –MgO inclusion in the electrode to Al 2 O 3 –MgO–Ce 2 O 3 and Al 2 O 3 –Ce 2 O 3 inclusions in the ESR ingot. In case of low CeO 2 /Al 2 O 3 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 CeO 2 /Al 2 O 3 ratio of 5.0, oxygen content decreases further to 6 ppm no matter what the condition is.