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Steel Making

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

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

Gears
The material used for all gears on the Liberty engine was sel...

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

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

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

Ebbw Vale And The Bessemer Process
After his British Association address in August 1856, Besseme...

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

Hardening High-speed Steels
We will now take up the matter of hardening high-speed steels...

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

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

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

S A E Heat Treatments
The Society of Automotive Engineers have adopted certain heat...

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

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

Corrosion
This steel like any other steel when distorted by cold worki...

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

High-chromium Or Rust-proof Steel
High-chromium, or what is called stainless steel containing f...

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

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



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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