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Steel Making

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

Carbon Steels For Different Tools
All users of tool steels should carefully study the different...

Manganese
Manganese adds considerably to the tensile strength of steel,...

Nickel
Nickel may be considered as the toughest among the non-rare a...

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

Steel Can Be Worked Cold
As noted above, steel can be worked cold, as in the case of ...

Carburizing By Gas
The process of carburizing by gas, briefly mentioned on page ...

Connecting Rods
The material used for all connecting rods on the Liberty engi...

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

Knowing What Takes Place
How are we to know if we have given a piece of steel the ver...

Care In Annealing
Not only will benefits in machining be found by careful anne...

Annealing
There is no mystery or secret about the proper annealing of d...

Cyanide Bath For Tool Steels
All high-carbon tool steels are heated in a cyanide bath. Wi...

Placing The Thermo-couples
The following illustrations from the Taylor Instrument Compan...

Fatigue Tests
It has been known for fifty years that a beam or rod would fa...

Steel For Chisels And Punches
The highest grades of carbon or tempering steels are to be re...

Preventing Carburizing By Copper-plating
Copper-plating has been found effective and must have a thick...

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

The Care Of Carburizing Compounds
Of all the opportunities for practicing economy in the heat-t...

Carburizing Material
The simplest carburizing substance is charcoal. It is also th...



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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