On the problem of boron deoxidation and its effect on microalloying

Object of research: boron-containing steels. Method of study: analysis of deoxidation thermodynamics in the Fe-B-O system. Purpose: The choice of the most reliable constant values of iron deoxidation with boron as well as on the basis of this, the development of the most effective technologies of microalloying with boron. In the work on the basis of theoretical and experimental data got by various au-thors, the iron deoxidation with boron over the range 0,001% to 0,01% is analyzed. It is shown that boron oxide В2О3 forms independently of the boron content in the Fe-B-O melt. It is shown that the data of thermodynamic calculations and experimental researches by different authors (irrespective of the method of their calculations) differ just slightly. At 1600°C, the value of the deoxidation constants according to the data got by various authors is relatively stable and is: K-1В-O = (0,36-0,46)•10-8. For practical calculations the work of I.S. Kulikova should be recommended. The effect of boron on the oxygen activity is relatively low. With boron content of less than 0,1% in case of В2О3, formation the interaction parameter will be = -(0,39-0,40). The effect of boron on its own activity is estimated by the coefficient = 0,065 + 0,01[В]. The microalloying with boron as well as its peculiarities have been studied. Boron influence on the operational properties of steel due to structural changes during crystallization and heat treat-ment have been studied The practice of microalloying with boron, technology of out-of-furnace treatment, including joint doping with strong deoxidizers aluminum and calcium, has been considered