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Heat Treatment Of Lathe Planer And Similar Tools
FIRE.--For these tools a good fire is one made of hard foundr...

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

Chromium when alloyed with steel, has the characteristic func...

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

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

Annealing Work
With the exception of several of the higher types of alloy s...

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

The Electric Process
The fourth method of manufacturing steel is by the electric f...

Shrinking And Enlarging Work
Steel can be shrunk or enlarged by proper heating and cooling...

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

Leeds And Northrup Optical Pyrometer
The principles of this very popular method of measuring tempe...

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

Correction For Cold-junction Errors
The voltage generated by a thermo-couple of an electric pyrom...

The Effect
The heating at 1,600 deg.F. gives the first heat treatment w...

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

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

Application Of Liberty Engine Materials To The Automotive Industry
The success of the Liberty engine program was an engineer...

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

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

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

Short Method Of Treatment


In the new method, the packed pots are
run into the case-hardening furnaces, which are heated to 1,600 deg.F.
On the insertion of the cold pots, the temperature naturally falls.
The amount of this fall is dependent upon a number of variables,
but it averages nearly 500 deg.F. as shown in the pyrometer chart,
Fig. 61. The work and furnace must be brought to 1,600 deg.F. Within
2-1/2 hr.; otherwise, a longer time will be necessary to obtain
the desired depth of case. On this work, the depth of case required
is designated in thousandths, and on crown gears, the depth in
0.028 in. Having brought the work to a temperature of 1,600 deg.F.
the depth of case mentioned can be obtained in about 5-1/2 hr. by
maintaining this temperature.

As stated before, at the top of each pot are several test pieces
consisting of a whole scrap gear and several sections. After the
pots have been heated at 1,600 deg.F. for about 5-1/4 hr., they are
removed, and a scrap-section test-piece is quenched direct from
the pot in mineral oil at not more than 100 deg.F. The end of a tooth
of this is then ground and etched to ascertain the depth of case.
As these test pieces are of exactly the same cross-section as the
gears themselves, the carburizing action is similar. When the depth
of case has been found from the etched test pieces to be satisfactory,
the pots are removed. The iron ball then is dropped into the tube
to seal the hole in the bottom of the pot; the cover and the tube
are removed, and the gears quenched direct from the pot in mineral
oil, which is kept at a temperature not higher than 100 deg.F.

Next: The Effect

Previous: The Packing Department

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