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Steel Making

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

William Kelly's Air-boiling Process
An account of Bessemer's address to the British Association w...

Optical System And Electrical Circuit Of The Leeds & Northrup Optical Pyrometer
For extremely high temperature, the optical pyrometer is lar...

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

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

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

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

Oil-hardening Steel
Heat slowly and uniformly to 1,450 deg.F. and forge thorough...

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

Fatigue Tests
It has been known for fifty years that a beam or rod would fa...

Pyrometers For Molten Metal
Pyrometers for molten metal are connected to portable thermoc...

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

Classifications Of Steel
Among makers and sellers, carbon tool-steels are classed by g...

Temperatures To Use
As soon as the temperature of the steel reaches 100 deg.C. (...

Correction By Zero Adjustment
Many pyrometers are supplied with a zero adjuster, by means ...

Armor plate makers sometimes use the copper ball or Siemens' ...

Tempering Round Dies
A number of circular dies of carbon tool steel for use in too...

Annealing Work
With the exception of several of the higher types of alloy s...

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

Hardening High-speed Steel
In forging use coke for fuel in the forge. Heat steel slowly ...

Annealing Of High-speed Steel


For annealing high-speed steel, some makers recommend using ground
mica, charcoal, lime, fine dry ashes or lake sand as a packing
in the annealing boxes. Mixtures of one part charcoal, one part
lime and three parts of sand are also suggested, or two parts of
ashes may be substituted for the one part of lime.

To bring about the softest structure or machine ability of high-speed
steel, it should be packed in charcoal in boxes or pipes, carefully
sealed at all points, so that no gases will escape or air be admitted.
It should be heated slowly to not less than 1,450 deg.F. and the steel
must not be removed from its packing until it is cool. Slow heating
means that the high heat must have penetrated to the very core of
the steel.

When the steel is heated clear through it has been in the furnace
long enough. If the steel can remain in the furnace and cool down
with it, there will be no danger of air blasts or sudden or uneven
cooling. If not, remove the box and cover quickly with dry ashes,
sand or lime until it becomes cold.

Too high a heat or maintaining the heat for too long a period,
produces a harsh, coarse grain and greatly increases the liability
to crack in hardening. It also reduces the strength and toughness
of the steel.

Steel which is to be used for making tools with teeth, such as
taps, reamers and milling cutters, should not be annealed too much.
When the steel is too soft it is more apt to tear in cutting and
makes it more difficult to cut a smooth thread or other surface.
Moderate annealing is found best for tools of this kind.

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