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

Silicon
Silicon prevents, to a large extent, defects such as gas bubb...

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

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

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

A Satisfactory Luting Mixture
A mixture of fireclay and sand will be found very satisfactor...

Phosphorus
PHOSPHORUS is an element (symbol P) which enters the metal fr...

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

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

Quality And Structure
The quality of high-speed steel is dependent to a very great ...

The Modern Hardening Room
A hardening room of today means a very different place from ...

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

Temperature Recording And Regulation
Each furnace is equipped with pyrometers, but the reading an...

Introduction Of Carbon
The matter to which these notes are primarily directed is the...

Bessemer Process
The bessemer process consists of charging molten pig iron int...

The Effect Of Tempering On Water-quenched Gages
The following information has been supplied by Automatic and ...

Pyrometers
Armor plate makers sometimes use the copper ball or Siemens' ...

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

Making Steel Balls
Steel balls are made from rods or coils according to size, st...

The Penetration Of Carbon
Carburized mild steel is used to a great extent in the manufa...



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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