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

Preventing Carburizing By Copper-plating
Copper-plating has been found effective and must have a thick...

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

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

Standard Analysis
The selection of a standard analysis by the manufacturer is t...

Open Hearth Process
The open hearth furnace consists of a big brick room with a l...

Composition Of Transmission-gear Steel
If the nickel content of this steel is eliminated, and the pe...

Judging The Heat Of Steel
While the use of a pyrometer is of course the only way to hav...

A combination of the characteristics of nickel and the charac...

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

The Leeds And Northrup Potentiometer System
The potentiometer pyrometer system is both flexible and subst...

Heat Treatment Of Axles
Parts of this general type should be heat-treated to show the...

An Automatic Temperature Control Pyrometer
Automatic temperature control instruments are similar to the ...

SILICON is a very widespread element (symbol Si), being an es...

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

Alloying Elements
Commercial steels of even the simplest types are therefore p...

Process Of Carburizing
Carburizing imparts a shell of high-carbon content to a low-...

Knowing What Takes Place
How are we to know if we have given a piece of steel the ver...

ANNEALING can be done by heating to temperatures ranging from...

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

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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