Numerical investigation of titanium anode evapor ation loss during Ar-H2 arc melting-refining

High-purity titanium is widely used in aerospace, electronic information, and advanced functional materials. During arc melting and refining, however, titanium evaporation causes metal burn-off, reduces material yield, and affects refining efficiency. Hydrogen addition can significantly modify arc heat transfer and plasma transport, yet its influence on titanium evaporation remains insufficiently understood. In this study, a two-dimensional axisymmetric numerical model was developed to investigate arc heat transfer and titanium anode evaporation under different current intensities and Ar–H2 atmospheres. The electromagnetic, flow, and thermal fields were solved simultaneously to determine the arc temperature, plasma flow, and anode heat input, while an apparent heat capacity method together with a surface recession model was employed to simulate transient melting, crater evolution, and evaporation loss of the titanium anode. The results show that increasing current intensity enlarges the high-temperature region, strengthens the axial plasma jet, and enhances heat and momentum transport toward the anode. Hydrogen addition modifies the thermophysical properties of the plasma, promotes arc constriction and enthalpy transport, and concentrates heat input near the arc attachment region, resulting in deeper evaporation craters and higher titanium evaporation loss rates. The predicted evaporation losses under Ar, Ar–10%H2, and Ar–20%H2 atmospheres agree well with experimental measurements, with an average relative error of approximately 5%. The proposed model clarifies the relationship between arc heat transfer and titanium evaporation and provides a quantitative basis for understanding hydrogen-enhanced burn-off and optimizing arc melting-refining processes.