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Steel Making

Steel is hardened by quenching from above the upper critical....

Carbon Tool Steel
Heat to a bright red, about 1,500 to 1,550 deg.F. Do not ham...

Optical System And Electrical Circuit Of The Leeds & Northrup Optical Pyrometer
For extremely high temperature, the optical pyrometer is lar...

Take Time For Hardening
Uneven heating and poor quenching has caused loss of many ve...

Tempering Colors On Carbon Steels
Opinions differ as to the temperature which is indicated by t...

Gas Consumption For Carburizing
Although the advantages offered by the gas-fired furnace for ...

The material used for all gears on the Liberty engine was sel...

S A E Heat Treatments
The Society of Automotive Engineers have adopted certain heat...

William Kelly's Air-boiling Process
An account of Bessemer's address to the British Association w...

Properties Of Steel
Steels are known by certain tests. Early tests were more or l...

Heat Treatment Of Punches And Dies Shears Taps Etc
HEATING.--The degree to which tools of the above classes shou...

Separating The Work From The Compound
During the pulling of the heat, the pots are dumped upon a ca...

Furnace Data
In order to give definite information concerning furnaces, fu...

The Forging Of Steel
So much depends upon the forging of steel that this operation...

Carbon In Tool Steel
Carbon tool steel, or tool steel as it is commonly called, us...

Non-shrinking Oil-hardening Steels
Certain steels have a very low rate of expansion and contract...

Fatigue Tests
It has been known for fifty years that a beam or rod would fa...

The Penetration Of Carbon
Carburized mild steel is used to a great extent in the manufa...

Annealing To Relieve Internal Stresses
Work quenched from a high temperature and not afterward tempe...

Short Method Of Treatment
In the new method, the packed pots are run into the case-har...

A Chromium-cobalt Steel


The Latrobe Steel Company make a high-speed steel without tungsten,
its red-hardness properties depending on chromium and cobalt instead
of tungsten. It is known as P. R. K-33 steel. It does not require
the high temperature of the tungsten steels, hardening at 1,830 to
1,850 deg.F. instead of 2,200 deg. or even higher, as with the tungsten.

This steel is forged at 1,900 to 2,000 deg.F. and must not be worked
at a lower temperature than 1,600 deg.F. It requires soaking in the
fire more than the tungsten steels. It can be normalized by heating
slowly and thoroughly to 1,475 deg.F., holding this for from 10 to 20
min. according to the size of the piece and cooling in the open
air, protected from drafts.

A peculiarity of this steel is that it becomes non-magnetic at or
above 1,960 deg.F. and the magnetic quality is not restored by cooling.
Normalizing as above, however, restores the magnetic qualities. This
enables the user to detect any tools which have been overheated,
with a horseshoe magnet.

It is sometimes advantageous to dip tools, before heating for hardening,
in ordinary fuel or quenching oil. The oil leaves a thin film of
carbon which tends to prevent decarbonization, giving a very hard

For other makes of high-speed steel used in lathe and planer tools
the makers recommend that the tools be cut from the bar with a
hack saw or else heated and cut with a chisel. The heating should
be very slow until the steel reaches a red after which it can be
heated more rapidly and should only be forged at a high heat. It
can be forged at very high heats but care should be taken not to
forge at a low heat. The heating should be uniform and penetrate
clear to the center of the bar before forging is begun. Reheat
as often as necessary to forge at the proper heat.

After forging cool in lime before attempting to harden. Do not
attempt to harden with the forging heat as was sometimes done with
the carbon tools.

For hardening forged tools, heat slowly up to a bright red and
then rapidly until the point of the tool is almost at a melting
heat. Cool in a blast of cold, dry air. For large sizes of steel,
cool in linseed oil or in fish oil as is most convenient. If the
tools are to be used for finishing cuts heat to a bright yellow
and quench in oil. Grind for use on a sand wheel or grindstone
in preference to an emery or an artificial abrasive wheel.

For hardening milling and similar cutters, preheat to a bright
red, place the cutter on a round bar of suitable size, and revolve
it quickly over a very hot fire. Heat as high as possible without
melting the points of the teeth and cool in a cold blast of dry
air or in fish oil.

Light fragile cutters, twist drills, taps and formed cutters may
be heated almost white and then dipped in fish oil for hardening.
Where possible it is better to give an even higher heat and cool
in the blast of cold, dry air as previously recommended.

Next: Suggestions For Handling High-speed Steels

Previous: Heat Treatment Of Punches And Dies Shears Taps Etc

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