acture of
high-speed steel is essential to steel treaters. It is well for
the manufacturer to have steel treaters understand some of his
troubles and difficulties, so that they will better comprehend the
necessity of certain trade customs and practices, and, realizing
the manufacturer's desire to cooperate with them, will reciprocate.

The manufacturer of high-speed steel knows and appreciates the
troubles and difficulties that may sometimes arise in the heat-treating
of his product. His aim is to make a uniform steel that will best
meet the requirements of the average machine shop on general work,
and at the same time allow the widest variation in heat treatment
to give desired results.

High speed steel is one of the most complex alloys known. A
representative steel contains approximately 24 per cent of alloying
metals, namely, tungsten, chromium, vanadium, silicon, manganese,
and in addition there is often found cobalt, molybdenum, uranium,
nickel, tin, copper and arsenic.

STANDARD ANALYSIS

The selection of a standard analysis by the manufacturer is the
result of a series of compromises between various properties imparted
to the steel by the addition of different elements and there is a
wide range of chemical analyses of various brands. The steel, to
be within the range of generally accepted analysis, should contain
over 16 per cent and under 20 per cent tungsten; if of lower tungsten
content it should carry proportionately more chromium and vanadium.

The combined action of tungsten and chromium in steel gives to it the
remarkable property of maintaining its cutting edge at relatively high
temperature. This property is commonly spoken of as "red-hardness."
The percentages of tungsten and chromium present should bear a
definite relationship to each other. Chromium imparts to steel
a hardening property similar to that given by carbon, although
to a less degree. The hardness imparted to steel by chromium is
accompanied by brittleness. The chromium content should be between
3.5 and 5 per cent.

Vanadium was first introduced in high-speed steel as a "scavenger,"
thereby producing a more homogeneous product, of greater density
and physical strength. It soon became evident that vanadium used
in larger quantities than necessary as a scavenger imparted to
the steel a much greater cutting efficiency. Recently, no less an
authority than Prof. J. O. Arnold, of the University of Sheffield,
England, stated that "high-s