Employment of the Element in Metallurgy.
—It has been already mentioned that titanium itself is quite unsuitable for direct incorporation with steel. Besides the relatively low specific gravity (5·2), which would render mixing very difficult, the very high melting-point (given by Weiss and Kayser[614] as 2350°) would prevent uniform dissemination. The element is therefore generally used in the form of a ferro-titanium of low titanium content, 10-15 per cent. being the proportion usually employed. The addition should be made at the end of the Bessemer process, and after the addition of the required quantities of manganese and silicon alloys; the calculated quantity of ferro-titanium is added as the steel runs from the converter into the ladle. A suitable proportion is said to be one-half per cent. of alloy, so that the actual proportion of titanium to steel is somewhere about 1·5-1·8 lb. per ton. Six or eight minutes should be allowed after the addition, for the titaniferous slag to come to the surface.
[614] Zeitsch. anorg. Chem. 1910, 65, 345.
Although low percentage ferro-titanium is usually employed, it has been stated that high-percentage alloys, and even the element itself, are immediately taken up by steel if aluminium be added at the same time. Thus Venator[615] states that if titanium and aluminium be added together to the bath, both elements are immediately taken up, the reaction being very rapid and complete; the effects produced by the titanium are in no way influenced by the presence of the aluminium. Goldschmidt[616] proposes the use of ferro-titanium containing 24-25 per cent. of the element, with 3 per cent. of aluminium; this dissolves very readily, is very effective, and moreover, can be very easily prepared by the alumino-thermic reaction.
[615] Stahl Eisen, 1910, 30, 650.
[616] D. R. P. 235461, June, 1911.
In some cases, where it is desired to treat a steel both with silicon and with titanium, ferro-alloys containing both of these elements may be employed. By reduction of ilmenite or rutile with carbon in an electric furnace, in presence of silica, Becket[617] obtains alloys of high titanium and silicon content, which are said to dissolve very easily in molten steels and to produce improved effects. The Titanium Alloy Manufacturing Company have also patented[618] the preparation of titanium-silicon alloys, with or without addition of iron or copper, by the reduction of a mixture of rutile and quartz.
[617] U. S. P. 940665 and 941553 of November, 1909.
[618] F. 407858, January, 1910.
Recently the use of ferro-titanium in the manufacture of pig iron has attracted attention. For this purpose, alloys of very low titanium-content (0·1-1·0 per cent.) are employed. Addition of very small amounts of such alloys to the molten metal before casting is said to have a marked cleansing effect,[619] resulting in much better and stronger castings.