By vacuum induction melting 08Cr9CoMo steel using MgO crucible

the pure iron is derusted and baked with other alloys

the charging ingredients are 0. 06% C

1. 3% Co

9. 0% Cr

1. 5% Mo

0. 02% La-Ce

the balance is iron

turn on the power with vacuum ≤10 Pa

controlling the vacuum 25 ~30 Pa during the melting period

controlling the liquid temperature 1 600 °C and the vacuum 10 Pa during the refining period

and refining for 20 min

adding 0. 02% La-Ce before casting

the final analysis result is 0. 022% C and 0.002 8% 0. The carbon deoxidation capacity under vacuum is calculated by thermodynamics

and it is significantly enhanced as vacuum reduces

the relationship between oxygen supply of the MgO crucible and vacuum is analyzed by thermodynamic calculation

when the vacuum is lower than 25 Pa

the crucible decomposes and supplies oxygen more significantly

when the decomposition rate of the MgO crucible is equal to the carbon deoxidation rate

the molten steel reaches the minimum oxygen content.