Comparison of the results obtained from studies of the effect of boron microadditives on the structure and properties of liquid melts and of the alloys crystallizing out of such melts indicates that the reactions between boron and other highly active surfactants such as oxygen’ sulfur’ phosphorus’ nitrogen’ and carbon must be taken into account when determining the optimum amount of boron to be added. Thus’ in order for boron to have a greater effect on steel structurization and properties’ the most active surfactants — oxygen and sulfur — must be removed before the boron is added to the liquid metal.