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Steel Making

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

Drop Forging Dies
The kind of steel used in the die of course influences the he...

Hardening Operation
Hardening a gear is accomplished as follows: The gear is tak...

Instructions For Working High-speed Steel
Owing to the wide variations in the composition of high-speed...

Case-hardening Treatments For Various Steels
Plain water, salt water and linseed oil are the three most co...

Critical Points
One of the most important means of investigating the properti...

Complete Calibration Of Pyrometers
For the complete calibration of a thermo-couple of unknown e...

Highly Stressed Parts
The highly stressed parts on the Liberty engine consisted of ...

Application To The Automotive Industry
The information given on the various parts of the Liberty eng...

Double Annealing
Water annealing consists in heating the piece, allowing it to...

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

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

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

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

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

Carburizing Low-carbon Sleeves
Low-carbon sleeves are carburized and pushed on malleable-ir...

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

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

For Milling Cutters And Formed Tools
FORGING.--Forge as before.--ANNEALING.--Place the steel in a ...

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

Testing And Inspection Of Heat Treatment


The hard parts of the
gear must be so hard that a new mill file does not bite in the
least. Having passed this file test at several points, the gears go
to the center-punch test. The inspector is equipped with a wooden
trough secured to the top of the bench to support the gear, a number
of center punches (made of 3/4-in. hex-steel having points sharpened
to an angle of 120 deg.) and a hammer weighing about 4 oz. With
these simple tools, supplemented by his skill, the inspector can
feel the depth and quality of the case and the condition of the
core. The gears are each tested in this way at several points on
the teeth and elsewhere, the scrap gear being also subjected to
the test. Finally, the scrap gear is securely clamped in the
straightening press shown in Fig. 57. With a 3-1/2-lb. hammer and
a suitable hollow-ended drift manipulated by one of Sandow's
understudies, teeth are broken out of the scrap gear at various
points. These give a record confirming the center-punch tests,
which, if the angle of the center punch is kept at 120 deg. and
the weight of the hammer and blow are uniform, is very accurate.

After passing the center-punch test the ends of the teeth are peened
lightly with a hammer. If they are too hard, small particles fly
off. Such gears are drawn in oil at a temperature of from 300 to
350 deg.F., depending on their hardness. Some builders prefer to have
the extreme outer ends of the teeth drawn somewhat lower than the
rest. This drawing is done on gas-heated red-hot plates, as shown
at A in Fig. 58.

Nickel steel, in addition to all the tests given to carbon steel,
is subjected to a Brinell test. For each steel, the temperature
and the period of treatment are specific. For some unknown reason,
apparently like material with like treatment will, in isolated
cases, not produce like results. It then remains for the treatment
to be repeated or modified, but the results obtained during inspection
form a valuable aid to the metallurgist in determining further

Next: Temperature Recording And Regulation

Previous: Affinity Of Nickel Steel For Carbon

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