A few secrets of the metallurgist simply told

by Gerald W. Hinkley

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.