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

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

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

Pyrometry And Pyrometers
A knowledge of the fundamental principles of pyrometry, or th...

Alloying Elements
Commercial steels of even the simplest types are therefore p...

Restoring Overheated Steel
The effect of heat treatment on overheated steel is shown gra...

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

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

Carburizing Low-carbon Sleeves
Low-carbon sleeves are carburized and pushed on malleable-ir...

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

Standard Analysis
The selection of a standard analysis by the manufacturer is t...

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

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

A Satisfactory Luting Mixture
A mixture of fireclay and sand will be found very satisfactor...

Refining The Grain
This is remedied by reheating the piece to a temperature slig...

Heat Treatment Of Gear Blanks
This section is based on a paper read before the American Gea...

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

The Leeds And Northrup Potentiometer System
The potentiometer pyrometer system is both flexible and subst...

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

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



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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