THERMODYNAMIC CONDITIONS FOR THE NUCLEATION OF BORON COMPOUNDS DURING THE COOLING OF STEEL

The higher the value of the product of boron and oxygen concentrations, or of boron and nitrogen concentrations, than the value corresponding to the balance for the given temperature, is the thermo-dynamic criterion for the nucleation of a new phase (B2O3 or BN). It follows from the calculations that the theoretical temperature of the beginning of B2O3 nucleation is higher than the temperature of the beginning of BN nitride nucleation. During the solidification and cooling down of steel the boron oxide will be formed preferentially before the boron nitride.