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Steel Making

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

Application Of Liberty Engine Materials To The Automotive Industry
The success of the Liberty engine program was an engineer...

Placing The Thermo-couples
The following illustrations from the Taylor Instrument Compan...

Annealing In Bone
Steel and cast iron may both be annealed in granulated bone. ...

Typical Oil-fired Furnaces
Several types of standard oil-fired furnaces are shown herew...

Highly Stressed Parts
The highly stressed parts on the Liberty engine consisted of ...

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

Hardness Testing
The word hardness is used to express various properties of me...

Pyrometry And Pyrometers
A knowledge of the fundamental principles of pyrometry, or th...

Tool Or Crucible Steel
Crucible steel can be annealed either in muffled furnace or b...

Refining The Grain
This is remedied by reheating the piece to a temperature slig...

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

Testing And Inspection Of Heat Treatment
The hard parts of the gear must be so hard that a new mill f...

Steel For Chisels And Punches
The highest grades of carbon or tempering steels are to be re...

Effect Of Different Carburizing Material
[Illustrations: FIGS. 33 to 37.] Each of these different p...

Application To The Automotive Industry
The information given on the various parts of the Liberty eng...

Alloying Elements
Commercial steels of even the simplest types are therefore p...

Shrinking And Enlarging Work
Steel can be shrunk or enlarged by proper heating and cooling...

Temperature For Annealing
Theoretically, annealing should be accomplished at a tempera...

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



A Chromium-cobalt Steel






Category: HIGH-SPEED 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
surface.

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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