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Steel Making

Connecting Rods
The material used for all connecting rods on the Liberty engi...

Knowing What Takes Place
How are we to know if we have given a piece of steel the ver...

Preventing Decarbonization Of Tool Steel
It is especially important to prevent decarbonization in such...

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

Properties Of Alloy Steels
The following table shows the percentages of carbon, manganes...

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

Pickling The Forgings
The forgings were then pickled in a hot solution of either ni...

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

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

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

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

Case-hardening Treatments For Various Steels
Plain water, salt water and linseed oil are the three most co...

Making Steel Balls
Steel balls are made from rods or coils according to size, st...

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

Mushet And Bessemer
That Mushet was "used" by Ebbw Vale against Bessemer is, perh...

Quenching The Work
In some operations case-hardened work is quenched from the bo...

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

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

Introduction Of Carbon
The matter to which these notes are primarily directed is the...

Quenching
It is considered good practice to quench alloy steels from th...



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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