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Steel Worked In Austenitic State
As a general rule steel should be worked when it is in the a...

Tool Or Crucible Steel
Crucible steel can be annealed either in muffled furnace or b...

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

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

Heating
Although it is possible to work steels cold, to an extent de...

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

Cyanide Bath For Tool Steels
All high-carbon tool steels are heated in a cyanide bath. Wi...

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

Critical Points
One of the most important means of investigating the properti...

Separating The Work From The Compound
During the pulling of the heat, the pots are dumped upon a ca...

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

Flange Shields For Furnaces
Such portable flame shields as the one illustrated in Fig. 1...

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

Quality And Structure
The quality of high-speed steel is dependent to a very great ...

High-carbon Machinery Steel
The carbon content of this steel is above 30 points and is ha...

Heat Treatment Of Punches And Dies Shears Taps Etc
HEATING.--The degree to which tools of the above classes shou...

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

Heat-treating Equipment And Methods For Mass Production
The heat-treating department of the Brown-Lipe-Chapin Company...

Compensating Leads
By the use of compensating leads, formed of the same materia...

Hints For Tool Steel Users
Do not hesitate to ask for information from the maker as to t...



Quenching






Category: CASE-HARDENING OR SURFACE-CARBURIZING

It is considered good practice to quench alloy steels from the pot,
especially if the case is of any appreciable depth. The texture
of carbon steel will be weakened by the prolonged high heat of
carburizing, so that if we need a tough core, we must reheat it
above its critical range, which is about 1,600 deg.F. for soft steel,
but lower for manganese and nickel steels. Quenching is done in
either water, oil, or air, depending upon the results desired.
The steel is then very carefully reheated to refine the case, the
temperature varying from 1,350 to 1,450 deg.F., depending on whether
the material is an alloy or a simple steel, and quenched in either
water or oil.



There are many possibilities yet to be developed with the carburizing
of alloy steels, which can produce a very tough, tenacious austenitic
case which becomes hard on cooling in air, and still retains a
soft, pearlitic core. An austenitic case is not necessarily file
hard, but has a very great resistance to abrasive wear.

The more carbon a steel has to begin with the more slowly will it
absorb carbon and the lower the temperature required. Low-carbon
steel of from 15 to 20 points is generally used and the carbon
brought up to 80 or 85 points. Tool steels may be carbonized as
high as 250 points.

In addition to the carburizing materials given, a mixture of 40
per cent of barium carbonate and 60 per cent charcoal gives much
faster penetration than charcoal, bone or leather. The penetration
of this mixture on ordinary low-carbon steel is shown in Fig. 32,
over a range of from 2 to 12 hr.





Next: Effect Of Different Carburizing Material

Previous: Carburizing Material



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