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Steel Making

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

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

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

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

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

Carbon In Tool Steel
Carbon tool steel, or tool steel as it is commonly called, us...

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

Surface Carburizing
Carburizing, commonly called case-hardening, is the art of pr...

Blending The Compound
Essentially, this consists of the sturdy, power-driven separa...

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

Preparing Parts For Local Case-hardening
At the works of the Dayton Engineering Laboratories Company, ...

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

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

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

Temperature Recording And Regulation
Each furnace is equipped with pyrometers, but the reading an...

Hardening Operation
Hardening a gear is accomplished as follows: The gear is tak...

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

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

Take Time For Hardening
Uneven heating and poor quenching has caused loss of many ve...

Sulphur
SULPHUR is another element (symbol S) which is always found i...



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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