To reduce the lanthanum loss in La-containing GH4169 during electroslag process, the thermodynamic of lanthanum oxidation was investigated based on slag-steel reaction experiments and thermodynamic calculation. The results show that lanthanum in the alloy can react with Al2O3 and TiO2 in the slag, resulting in the loss of lanthanum in the alloy. With the increase of Al2O3 content in the slag from 18.41 wt-% to 24.73 wt-%, the yield of lanthanum decreased from 12.1% to 7.9%. When the La2O3 content in the slag increased from 3.99 wt-% to 10.14 wt-%, the yield of lanthanum in the alloy increased from 7.9% to 18.7%. With the increase of CaF2, Al2O3 and TiO2 contents in the slag, the activity of La2O3 decreases, which is in favour of lanthanum loss in the alloy. The activity of La2O3 increases with the increase of CaO, La2O3 and MgO content in the slag, which would restrain the loss of lanthanum in the alloy during electroslag remelting process.
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