Vanadium steels are still in their infancy. Therefore, the true value of this element in rapid steels must probably be held as not yet fully determined. With the single exception of carbon, no element has such a powerful effect upon steel as vanadium, for it is only necessary to use from 0.10 to 0.15% in order to obtain very noticeable results. In addition to acting as a very great strengthener of steel, especially against dynamic strains, vanadium also serves as a scavenger in getting rid of oxygen and possibly nitrogen. It is also said to decrease segregation, which we may readily believe, as most of the elements which quiet the steel have this effect.
"Vanadium Steels" demand a somewhat higher price than do those steels which do not contain this element in appreciable amounts. It is, of course, especially useful for all purposes where strength and lightness are desired, such as springs, axles, frames and other parts of railroad rolling stock, and automobiles.
COBALT.
The valuable effect of cobalt is claimed to be that it increases the red hardness of high speed tool steel, enabling the steel to cut at a higher speed. However, this element much resembles nickel, which has been largely condemned as not being a desirable ingredient for high speed tool steels, because it has the effect of making the edge of the finished tool soft or "leady".
URANIUM, TITANIUM AND ALUMINUM.
These elements are generally classed as scavengers, although recently important claims have been advanced for their effect upon the physical properties of steel. This is especially true for the first two. In present practice, however, they are used almost entirely as deoxidizers or cleansers, and are added to the metal for this purpose only.
IMPURITIES.
Phosphorus, Sulphur and Copper are the most noted impurities which occur in steel. The first two are practically always present in greater or smaller amounts as the case may be. The best processes of tool steel manufacture are capable of producing steels with no copper. While Aluminum is not generally classed as an impurity, it nevertheless sometimes shows up in the finished product when its presence is not desired, and therefore, might be considered an impurity.
Combinations of iron with some or all of the above elements in the form of slags and oxides are other well known impurities.
From the forgoing pages it must be evident that producing a steel with exactly the correct chemical content is only one step towards securing a satisfactory product. However, it might be well if we were to briefly sum up a few of the more important features of our discussion on this interesting subject.