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

Mushet And Bessemer
That Mushet was "used" by Ebbw Vale against Bessemer is, perh...

Heat-treating Equipment And Methods For Mass Production
The heat-treating department of the Brown-Lipe-Chapin Company...

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

Correction By Zero Adjustment
Many pyrometers are supplied with a zero adjuster, by means ...

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

Cutting-off Steel From Bar
To cut a piece from an annealed bar, cut off with a hack saw,...

Carbon Tool Steel
Heat to a bright red, about 1,500 to 1,550 deg.F. Do not ham...

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

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

Tensile Properties
Strength of a metal is usually expressed in the number of pou...

Lathe And Planer Tools
FORGING.--Gently warm the steel to remove any chill, is parti...

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

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

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

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

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

Lathe And Planer Tools
TO FORGE.--Gently warm the steel to remove any chill is parti...

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

Affinity Of Nickel Steel For Carbon
The carbon- and nickel-steel gears are carburized separately...



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.





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Previous: Rate Of Absorption



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