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Steel Making

Temperature Recording And Regulation
Each furnace is equipped with pyrometers, but the reading an...

Tool Or Crucible Steel
Crucible steel can be annealed either in muffled furnace or b...

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

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

Carbon-steel Forgings
Low-stressed, carbon-steel forgings include such parts as car...

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

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

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

Steel For Chisels And Punches
The highest grades of carbon or tempering steels are to be re...

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

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

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

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

A Chromium-cobalt Steel
The Latrobe Steel Company make a high-speed steel without tun...

Steel Can Be Worked Cold
As noted above, steel can be worked cold, as in the case of ...

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

Steel Before The 1850's
In spite of a rapid increase in the use of machines and the ...

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

SULPHUR is another element (symbol S) which is always found i...

Martien was probably never a serious contender for the honor ...

Fatigue Tests


It has been known for fifty years that a beam or rod would fail
at a relatively low stress if only repeated often enough. It has
been found, however, that each material possesses a limiting stress,
or endurance limit, within which it is safe, no matter how often
the loading occurs. That limiting stress for all steels so far
investigated causes fracture below 10 million reversals. In other
words, a steel which will not break before 10,000,000 reversals
can confidently be expected to endure 100,000,000, and doubtless
into the billions.

About the only way to test one piece such a large number of times
is to fashion it into a beam, load it, and then turn the beam in
its supports. Thus the stress in the outer fibers of the bar varies
from a maximum stretch through zero to a maximum compression, and
back again. A simple machine of this sort is shown in Fig. 10,
where B and E are bearings, A the test piece, turned slightly
down in the center, C and D ball bearings supporting a load
W. K is a pulley for driving the machine and N is a counter.

Next: Hardness Testing

Previous: Impact Tests

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