rong as a
0.45 carbon steel with 1.5 per cent nickel. The former steel is
much used for rifle barrels, and in the heat-treated condition will
give 80,000 to 90,000 lb. per square inch elastic limit, 115,000 to
125,000 lb. per square inch tensile strength, 23 per cent elongation,
and 55 per cent reduction in area.

Manganese when added to steel has the effect of lowering the critical
range; 1 per cent manganese will lower the upper critical point
60 deg.F. The action of manganese is very similar to that of nickel
in this respect, only twice as powerful. As an instance, 1 per
cent nickel would have the effect of lowering the upper critical
range from 25 to 30 deg.F.

Low-carbon pearlitic-manganese steel, heat-treated, will give dynamic
strength which cannot be equaled by low-priced and necessarily
low-content nickel steels. In many instances, it is preferable to use
high-grade manganese steel, rather than low-content nickel steel.

High-manganese steels or austenite manganese steels are used for a
variety of purposes where great resistance to abrasion is required,
the percentage of manganese being from 11 to 14 per cent, and carbon
1 to 1.5 per cent. This steel is practically valueless unless
heat-treated; that is, heated to about yellow red and quenched
in ice water. The structure is then austenite and the air-cooled
structure of this steel is martensite. Therefore this steel has to
be heated and very rapidly cooled to obtain the ductile austenite
structure.

Manganese between 2 and 7 per cent is a very brittle material when
the carbon is about 1 per cent or higher and is, therefore, quite
valueless. Below 2 per cent manganese steel low in carbon is very
ductile and tough steel.

The high-content manganese steels are known as the "Hadfield manganese
steels," having been developed by Sir Robert Hadfield. Small additions
of chrome up to 1 per cent increase the elastic limit of low-carbon
pearlitic-manganese steels without affecting the steel in its resistance
to shock, but materially decrease the percentage of elongation.

Vanadium added to low-carbon pearlitic manganese steel has a very
marked effect, increasing greatly the dynamic strength and changing
slightly the susceptibility of this steel to heat treatments, giving
a greater margin for the hardening temperature. Manganese steel
with added vanadium is most efficient when heat-treated.

TUNGSTEN

Tungsten, as an alloy in steel, has been known and used for a