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Hardening
Steel is hardened by quenching from above the upper critical....

Introduction Of Carbon
The matter to which these notes are primarily directed is the...

Crankshaft
The crankshaft was the most highly stressed part of the entir...

Protectors For Thermo-couples
Thermo-couples must be protected from the danger of mechanica...

Annealing Method
Forgings which are too hard to machine are put in pots with ...

Quenching The Work
In some operations case-hardened work is quenched from the bo...

Nickel
Nickel may be considered as the toughest among the non-rare a...

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

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

The Care Of Carburizing Compounds
Of all the opportunities for practicing economy in the heat-t...

Effects Of Proper Annealing
Proper annealing of low-carbon steels causes a complete solu...

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

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

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

Vanadium
Vanadium has a very marked effect upon alloy steels rich in c...

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

The Theory Of Tempering
Steel that has been hardened is generally harder and more br...

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

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

Composition And Properties Of Steel
It is a remarkable fact that one can look through a dozen tex...



Testing And Inspection Of Heat Treatment






Category: HEAT TREATMENT OF STEEL

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
treatment.





Next: Temperature Recording And Regulation

Previous: Affinity Of Nickel Steel For Carbon



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