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

Judging The Heat Of Steel
While the use of a pyrometer is of course the only way to hav...

The Effect Of Tempering On Water-quenched Gages
The following information has been supplied by Automatic and ...

Tungsten
Tungsten, as an alloy in steel, has been known and used for a...

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

An Automatic Temperature Control Pyrometer
Automatic temperature control instruments are similar to the ...

Nickel-chromium
A combination of the characteristics of nickel and the charac...

Heating Of Manganese Steel
Another form of heat-treating furnace is that which is used ...

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

Calibration Of Pyrometer With Common Salt
An easy and convenient method for standardization and one whi...

Annealing
ANNEALING can be done by heating to temperatures ranging from...

Tensile Properties
Strength of a metal is usually expressed in the number of pou...

Heat Treatment Of Lathe Planer And Similar Tools
FIRE.--For these tools a good fire is one made of hard foundr...

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

Liberty Motor Connecting Rods
The requirements for materials for the Liberty motor connecti...

Steel Before The 1850's
In spite of a rapid increase in the use of machines and the ...

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

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

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

Heat Treatment Of Milling Cutters Drills Reamers Etc
THE FIRE.--Gas and electric furnaces designed for high heats ...



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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