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Steel Making

The Influence Of Size
The size of the piece influences the physical properties obta...

Lathe And Planer Tools
FORGING.--Gently warm the steel to remove any chill, is parti...

The Quenching Tank
The quenching tank is an important feature of apparatus in c...

Typical Oil-fired Furnaces
Several types of standard oil-fired furnaces are shown herew...

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

Ebbw Vale And The Bessemer Process
After his British Association address in August 1856, Besseme...

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

Heat-treating Department
The heat-treating department occupies an L-shaped building. ...

Bessemer Process
The bessemer process consists of charging molten pig iron int...

Fatigue Tests
It has been known for fifty years that a beam or rod would fa...

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

Robert Mushet
Robert (Forester) Mushet (1811-1891), born in the Forest of D...

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

Annealing Alloy Steel
The term alloy steel, from the steel maker's point of view, r...

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

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

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

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

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

A Satisfactory Luting Mixture
A mixture of fireclay and sand will be found very satisfactor...



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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