SULPHUR.
Sulphur has just the opposite effect of Phosphorus, and makes the steel crack while it is being hot worked, although after the metal is cold it seems to have no particular effect upon the physical properties.
ELEMENTS WHICH HAVE BECOME ESPECIALLY ASSOCIATED WITH SPECIAL ALLOY STEELS.
Such elements are:—Chromium, Tungsten, Molybdenum, Vanadium, Cobalt, Uranium, Titanium, Aluminum, etc.