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Steel Making

William Kelly's Air-boiling Process
An account of Bessemer's address to the British Association w...

The Forging Of Steel
So much depends upon the forging of steel that this operation...

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

Testing And Inspection Of Heat Treatment
The hard parts of the gear must be so hard that a new mill f...

Properties Of Steel
Steels are known by certain tests. Early tests were more or l...

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

Phosphorus is one of the impurities in steel, and it has been...

Quenching Tool Steel
To secure proper hardness, the cooling of quenching of steel ...

Compensating Leads
By the use of compensating leads, formed of the same materia...

Hardening High-speed Steels
We will now take up the matter of hardening high-speed steels...

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

Detrimental Elements
Sulphur and phosphorus are two elements known to be detrimen...

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

Correction By Zero Adjustment
Many pyrometers are supplied with a zero adjuster, by means ...

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

Preventing Decarbonization Of Tool Steel
It is especially important to prevent decarbonization in such...

Brown Automatic Signaling Pyrometer
In large heat-treating plants it has been customary to mainta...

Surface Carburizing
Carburizing, commonly called case-hardening, is the art of pr...

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

Hints For Tool Steel Users
Do not hesitate to ask for information from the maker as to t...

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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