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Protectors For Thermo-couples
Thermo-couples must be protected from the danger of mechanica...

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

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

Hardening High-speed Steels
We will now take up the matter of hardening high-speed steels...

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

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

Leeds And Northrup Optical Pyrometer
The principles of this very popular method of measuring tempe...

Hardening Carbon Steel For Tools
For years the toolmaker had full sway in regard to make of st...

Cutting-off Steel From Bar
To cut a piece from an annealed bar, cut off with a hack saw,...

The Thermo-couple
With the application of the thermo-couple, the measurement of...

Lathe And Planer Tools
TO FORGE.--Gently warm the steel to remove any chill is parti...

Affinity Of Nickel Steel For Carbon
The carbon- and nickel-steel gears are carburized separately...

Effect Of A Small Amount Of Copper In Medium-carbon Steel
This shows the result of tests by C. R. Hayward and A. B. Joh...

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

High Speed Steel
For centuries the secret art of making tool steel was handed ...

Effects Of Proper Annealing
Proper annealing of low-carbon steels causes a complete solu...

Chromium
Chromium when alloyed with steel, has the characteristic func...

The Packing Department
In Fig. 56 is shown the packing pots where the work is packe...

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

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



Hardening High-speed Steels






Category: HIGH-SPEED STEEL

We will now take up the matter of hardening high-speed steels. The
most ordinary tools used are for lathes and planers. The forging
should be done at carbon-steel heat. Rough-grind while still hot
and preheat to about carbon-steel hardening heat, then heat quickly
in high-speed furnace to white heat, and quench in oil. If a very
hard substance is to be cut, the point of tool may be quenched in
kerosene or water and when nearly black, finish cooling in oil.
Tempering must be done to suit the material to be cut. For cutting
cast iron, brass castings, or hard steel, tempering should be done
merely to take strains out of steel.

On ordinary machinery steel or nickel steel the temper can be drawn
to a dark blue or up to 900 deg.F. If the tool is of a special form
or character, the risk of melting or scaling the point cannot be
taken. In these cases the tool should be packed, but if there is
no packing equipment, a tool can be heated to as high heat as is
safe without risk to cutting edges, and cyanide or prussiate of
potash can be sprinkled over the face and then quenched in oil.

Some very adverse criticism may be heard on this point, but experience
has proved that such tools will stand up very nicely and be perfectly
free from scales or pipes. Where packing cannot be done, milling
cutters, and tools to be hardened all over, can be placed in muffled
furnace, brought to 2,220 deg. and quenched in oil. All such tools,
however, must be preheated slowly to 1,400 to 1,500 deg. then placed in
a high-speed furnace and brought up quickly. Do not soak high-speed
steel at high heats. Quench in oil.

We must bear in mind that the heating furnace is likely to expand
tools, therefore provision must be made to leave extra stock to
take care of such expansion. Tools with shanks such as counter
bores, taps, reamers, drills, etc., should be heated no further
than they are wanted hard, and quench in oil. If a forge is not
at hand and heating must be done, use a muffle furnace and cover
small shanks with a paste from fire clay or ground asbestos. Hollow
mills, spring threading dies, and large cutting tools with small
shanks should have the holes thoroughly packed or covered with
asbestos cement as far as they are wanted soft.





Next: Cutting-off Steel From Bar

Previous: Quality And Structure



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