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Steel Making

Chromium
Chromium when alloyed with steel, has the characteristic func...

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

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

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

Carbon-steel Forgings
Low-stressed, carbon-steel forgings include such parts as car...

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

Chrome-nickel Steel
Forging heat of chrome-nickel steel depends very largely on ...

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

Heat-treating Department
The heat-treating department occupies an L-shaped building. ...

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

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

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

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

Steel Before The 1850's
In spite of a rapid increase in the use of machines and the ...

The Influence Of Size
The size of the piece influences the physical properties obta...

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

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

Crucible Steel
Crucible steel is still made by melting material in a clay or...

Process Of Carburizing
Carburizing imparts a shell of high-carbon content to a low-...

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



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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