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Steel Making

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

The Packing Department
In Fig. 56 is shown the packing pots where the work is packe...

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

Vanadium
Vanadium has a very marked effect upon alloy steels rich in c...

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

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

Hardening
Steel is hardened by quenching from above the upper critical....

Highly Stressed Parts
The highly stressed parts on the Liberty engine consisted of ...

Hardening Carbon Steel For Tools
For years the toolmaker had full sway in regard to make of st...

Quenching
It is considered good practice to quench alloy steels from th...

Effect Of A Small Amount Of Copper In Medium-carbon Steel
This shows the result of tests by C. R. Hayward and A. B. Joh...

Short Method Of Treatment
In the new method, the packed pots are run into the case-har...

The Penetration Of Carbon
Carburized mild steel is used to a great extent in the manufa...

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

The Quenching Tank
The quenching tank is an important feature of apparatus in c...

Complete Calibration Of Pyrometers
For the complete calibration of a thermo-couple of unknown e...

Robert Mushet
Robert (Forester) Mushet (1811-1891), born in the Forest of D...

The Electric Process
The fourth method of manufacturing steel is by the electric f...

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

Protective Screens For Furnaces
Workmen needlessly exposed to the flames, heat and glare from...



Carburizing Material






Category: CASE-HARDENING OR SURFACE-CARBURIZING

The simplest carburizing substance is charcoal. It is also the
slowest, but is often used mixed with something that will evolve
large volumes of carbon monoxide or hydrocarbon gas on being heated.
A great variety of materials is used, a few of them being charcoal
(both wood and bone), charred leather, crushed bone, horn, mixtures
of charcoal and barium carbonate, coke and heavy oils, coke treated
with alkaline carbonates, peat, charcoal mixed with common salt,
saltpeter, resin, flour, potassium bichromate, vegetable fibre,
limestone, various seed husks, etc. In general, it is well to avoid
complex mixtures.

H. L. Heathcote, on analyzing seventeen different carburizers, found
that they contained the following ingredients:

Per cent
Moisture 2.68 to 26.17
Oil 0.17 to 20.76
Carbon (organic) 6.70 to 54.19
Calcium phosphate 0.32 to 74.75
Calcium carbonate 1.20 to 11.57
Barium carbonate nil to 42.00
Zinc oxide nil to 14.50
Silica nil to 8.14
Sulphates (SO3) trace to 3.45
Sodium chloride nil to 7.88
Sodium carbonate nil to 40.00
Sulphides (S) nil to 2.80

Carburizing mixtures, though bought by weight, are used by volume,
and the weight per cubic foot is a big factor in making a selection.
A good mixture should be porous, so that the evolved gases, which
should be generated at the proper temperature, may move freely
around the steel objects being carburized; should be a good conductor
of heat; should possess minimum shrinkage when used; and should
be capable of being tamped down.

Many secret mixtures are sold, falsely claimed to be able to
convert inferior metal into crucible tool steel grade. They are
generally nothing more than mixtures of carbonaceous and cyanogen
compounds possessing the well-known carburizing properties of those
substances.





Next: Quenching

Previous: Rate Of Absorption



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