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Suggestions For Handling High-speed Steels
The following suggestions for handling high-speed steels are ...

Hardening
The forgings can be hardened by cooling in still air or quen...

Ebbw Vale And The Bessemer Process
After his British Association address in August 1856, Besseme...

A Satisfactory Luting Mixture
A mixture of fireclay and sand will be found very satisfactor...

Piston Pin
The piston pin on an aviation engine must possess maximum res...

Quenching Tool Steel
To secure proper hardness, the cooling of quenching of steel ...

Phosphorus
Phosphorus is one of the impurities in steel, and it has been...

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

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

Heat Treatment Of Steel
Heat treatment consists in heating and cooling metal at defin...

Carbon Steels For Different Tools
All users of tool steels should carefully study the different...

Heat-treating Department
The heat-treating department occupies an L-shaped building. ...

Open Hearth Process
The open hearth furnace consists of a big brick room with a l...

Nickel
Nickel may be considered as the toughest among the non-rare a...

Drop Forging Dies
The kind of steel used in the die of course influences the he...

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

Annealing Alloy Steel
The term alloy steel, from the steel maker's point of view, r...

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

A Chromium-cobalt Steel
The Latrobe Steel Company make a high-speed steel without tun...

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



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.





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