1955 Volume 41 Issue 1 Pages 11-17
It has been early known that boron was reduced and alloyed with steel, when steel was melted under a covering borate-containing slag, and the steel was hardened. One of the authors has reported this facts. (cf. M. Hasegawa, "Effect of Special Elements on Iron & Steel, " 1950, Tokyo; M. Hasegawa, Tetsu-to-Hagane, Vol. 38, 1952, No. 7) Lately Speight also reported on the addition of boron to steel by the reduction of boron oxide, in detail.
Prior to this, as the authors have studied this problem, in this issue they report the preliminary experiments in laboratory and chiefly the results of industrial tests using 2-ton Heroult furnace.
The results of industrial application are as follows;
(1) The experiments were performed in 2-ton basic electric furnace and 15 specimens of low-chromium and low-manganese cast steel were made.
(2) 0-3kg of boric acid anhydrous (B2O3) was added in the final slag before tapPing, and it was reduced with less than 0.2% of aluminium and 0.15% of titanium. Then, after the killing for 5-15 min., the molten steel was tapped into ladle.
(3) In every case, the suitable amounts of boron could be alloyed in steel. The yield of boron changed with the melting conditions, of course, but in the stationary condition, 30-50% of boron was reduced approximately, in this experiments.
(4) The optimum amounts of B2O3 addition to promote the hardenability of steel were 0.05-0.02% in weight to steel.
(5) There was no difference between the steel made by this method and boron steel using boron-contaning ferro-alloys, in quality.
(6) The authors concluded that this method was not difficult, not expensive and suitable for making boron steel in practice.