Standard Analysis

: The Working Of Steel

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 ca
ry 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-speed steels containing vanadium have

a mean efficiency of 108.9, as against a mean efficiency of 61.9

obtained from those without vanadium content. A wide range of

vanadium content in steel, from 0.5 to 1.5 per cent, is permissible.

An ideal analysis for high-speed steel containing 18 per cent tungsten

is a chromium content of approximately 3.85 per cent; vanadium, 0.85

to 1.10 per cent, and carbon, between 0.62 and 0.77 per cent.