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Steel Making

Annealing
ANNEALING can be done by heating to temperatures ranging from...

Machineability
Reheating for machine ability was done at 100 deg. less than ...

Forging High-speed Steel
Heat very slowly and carefully to from 1,800 to 2,000 deg.F....

Using Illuminating Gas
The choice of a carburizing furnace depends greatly on the fa...

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

Placing Of Pyrometers
When installing a pyrometer, care should be taken that it re...

Plant For Forging Rifle Barrels
The forging of rifle barrels in large quantities and heat-tre...

Non-shrinking Oil-hardening Steels
Certain steels have a very low rate of expansion and contract...

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

Hardening High-speed Steel
In forging use coke for fuel in the forge. Heat steel slowly ...

Temperature For Annealing
Theoretically, annealing should be accomplished at a tempera...

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

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

Conclusions
Martien was probably never a serious contender for the honor ...

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

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

Heating Of Manganese Steel
Another form of heat-treating furnace is that which is used ...

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

Take Time For Hardening
Uneven heating and poor quenching has caused loss of many ve...

Blending The Compound
Essentially, this consists of the sturdy, power-driven separa...



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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