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MANGANESE is a metal much like iron. Its chemical symbol is M...

Hints For Tool Steel Users
Do not hesitate to ask for information from the maker as to t...

Air-hardening Steels
These steels are recommended for boring, turning and planing...

This steel like any other steel when distorted by cold worki...

Correction For Cold-junction Errors
The voltage generated by a thermo-couple of an electric pyrom...

Sulphur is another impurity and high sulphur is even a greate...

The Modern Hardening Room
A hardening room of today means a very different place from ...

Process Of Carburizing
Carburizing imparts a shell of high-carbon content to a low-...

Using Illuminating Gas
The choice of a carburizing furnace depends greatly on the fa...

Manganese adds considerably to the tensile strength of steel,...

Carbon-steel Forgings
Low-stressed, carbon-steel forgings include such parts as car...

A combination of the characteristics of nickel and the charac...

Bessemer Process
The bessemer process consists of charging molten pig iron int...

Compensating Leads
By the use of compensating leads, formed of the same materia...

Brown Automatic Signaling Pyrometer
In large heat-treating plants it has been customary to mainta...

Heat-treating Equipment And Methods For Mass Production
The heat-treating department of the Brown-Lipe-Chapin Company...

The Leeds And Northrup Potentiometer System
The potentiometer pyrometer system is both flexible and subst...

Plant For Forging Rifle Barrels
The forging of rifle barrels in large quantities and heat-tre...

The Pyrometer And Its Use
In the heat treatment of steel, it has become absolutely nece...

Uses Of The Various Tempers Of Carbon Tool Steel
DIE TEMPER.--No. 3: All kinds of dies for deep stamping, pres...



Chromium when alloyed with steel, has the characteristic function
of opposing the disintegration and reconstruction of cementite.
This is demonstrated by the changes in the critical ranges of this
alloy steel taking place slowly; in other words, it has a tendency
to raise the Ac range (decalescent points) and lower the Ar
range (recalescent points). Chromium steels are therefore capable
of great hardness, due to the rapid cooling being able to retard
the decomposition of the austenite.

The great hardness of chromium steels is also due to the formation
of double carbides of chromium and iron. This condition is not
removed when the steel is slightly tempered or drawn. This additional
hardness is also obtained without causing undue brittleness such as
would be obtained by any increase of carbon. The degree of hardness
of the lower-chrome steels is dependent upon the carbon content,
as chromium alone will not harden iron.

The toughness so noticeable in this steel is the result of the
fineness of structure; in this instance, the action is similar
to that of nickel, and the tensile strength and elastic limit is
therefore increased without any loss of ductility. We then have
the desirable condition of tough hardness, making chrome steels
extremely valuable for all purposes requiring great resistance
to wear, and in higher-chrome contents resistance to corrosion.
All chromium-alloy steels offer great resistance to corrosion and
erosion. In view of this, it is surprising that chromium steels
are not more largely used for structural steel work and for all
purposes where the steel has to withstand the corroding action
of air and liquids. Bridges, ships, steel building, etc., would
offer greater resistance to deterioration through rust if the
chromium-alloy steels were employed.

Prolonged heating and high temperatures have a very bad effect upon
chromium steels. In this respect they differ from nickel steels,
which are not so affected by prolonged heating, but chromium steels
will stand higher temperatures than nickel steels when the period
is short.

Chromium steels, due to their admirable property of increased hardness,
without the loss of ductility, make very excellent chisels and
impact tools of all types, although for die blocks they do not give
such good results as can be obtained from other alloy combinations.

For ball bearing steels, where intense hardness with great toughness
and ready recovery from temporary deflection is required, chromium
as an alloy offers the best solution.

Two per cent chromium steels; due to their very hard tough surface,
are largely used for armor-piercing projectiles, cold rolls, crushers,
drawing dies, etc.

The normal structure of chromium steels, with a very low carbon
content is roughly pearlitic up to 7 per cent, and martensitic
from 8 to 20 per cent; therefore, the greatest application is in
the pearlitic zone or the lower percentages.

Next: Nickel-chromium

Previous: Nickel

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