CASE-HARDENING OR SURFACE-CARBURIZING
Annealing Of Rifle Components At Springfield Armory
In general, all forgings of the components of the arms manufactured
at the Armory and all forgings for other ordnance establishments
are packed in charcoal, lime or suitable material and annealed
before being trans...
Carburizing, commonly called case-hardening, is the art of producing
a high-carbon surface, or case, upon a low carbon steel article.
Wrenches, locomotive link motions, gun mechanisms, balls and ball
Rate Of Absorption
According to Guillet, the absorption of carbon is favored by those
special elements which exist as double carbides in steel. For example,
manganese exists as manganese carbide in combination with the iron
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 o...
It is considered good practice to quench alloy steels from the pot,
especially if the case is of any appreciable depth. The texture
of carbon steel will be weakened by the prolonged high heat of
carburizing, so tha...
Effect Of Different Carburizing Material
[Illustrations: FIGS. 33 to 37.]
Each of these different packing materials has a different effect
upon the work in which it is heated. Charcoal by itself will give
a rather light case. Mixed with raw bone it will...
Quenching The Work
In some operations case-hardened work is quenched from the box by
dumping the whole contents into the quenching tank. It is common
practice to leave a sieve or wire basket to catch the work, allowing
The Quenching Tank
The quenching tank is an important feature of apparatus in
case-hardening--possibly more so than in ordinary tempering. One
reason for this is because of the large quantities of pieces usually
dumped into the tank ...
Refining The Grain
This is remedied by reheating the piece to a temperature slightly
above the critical temperature of the case, this temperature
corresponding ordinarily to that of steel having a carbon content
of 85 points, When th...
Case-hardening Treatments For Various Steels
Plain water, salt water and linseed oil are the three most common
quenching materials for case-hardening. Water is used for ordinary
work, salt water for work which must be extremely hard on the surface,
and oil fo...
Carburizing By Gas
The process of carburizing by gas, briefly mentioned on page 88,
consists of having a slowly revolving, properly heated, cylindrical
retort into which illuminating gas (a mixture of various hydrocarbons)
Preventing Carburizing By Copper-plating
Copper-plating has been found effective and must have a thickness
of 0.0005 in. Less than this does not give a continuous coating.
The plating bath used has a temperature of 170 deg.F. A voltage of
4.1 is to be mai...
Preparing Parts For Local Case-hardening
At the works of the Dayton Engineering Laboratories Company, Dayton,
Ohio, they have a large quantity of small shafts, Fig. 40, that
are to be case-hardened at A while the ends B and C are to
be left soft. Formerly...
The Penetration Of Carbon
Carburized mild steel is used to a great extent in the manufacture
of automobile and other parts which are likely to be subjected to
rough usage. The strength and ability to withstand hard knocks
depend to a very c...
Introduction Of Carbon
The matter to which these notes are primarily directed is the
introduction of carbon into the case of the article to be hardened.
In the first place the chances of success are increased by selecting
as few brands o...
Using Illuminating Gas
The choice of a carburizing furnace depends greatly on the facilities
available in the locality where the shop is situated and the nature
and quantity of the work to be done. The furnaces can be heated with
A Satisfactory Luting Mixture
A mixture of fireclay and sand will be found very satisfactory
for closing up the boxes, and by observing the appearance of the
work when taken out we can gage the suitability of the methods
employed, for unless th...
Gas Consumption For Carburizing
Although the advantages offered by the gas-fired furnace for carburizing
have been generally recognized in the past from points of view as
close temperature regulation, decreased attendance, and greater
The Care Of Carburizing Compounds
Of all the opportunities for practicing economy in the heat-treatment
department, there is none that offers greater possibilities for
profitable returns than the systematic cleaning, blending and reworking
Separating The Work From The Compound
During the pulling of the heat, the pots are dumped upon a cast-iron
screen which forms a table or apron for the furnace. Directly beneath
this table is located one of the steel conveyor carts, shown in Fig.