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

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

Uses Of The Various Tempers Of Carbon Tool Steel
DIE TEMPER.--No. 3: All kinds of dies for deep stamping, pres...

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

The Effect Of Tempering On Water-quenched Gages
The following information has been supplied by Automatic and ...

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

Hardening High-speed Steel
In forging use coke for fuel in the forge. Heat steel slowly ...

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

Effect Of Different Carburizing Material
[Illustrations: FIGS. 33 to 37.] Each of these different p...

Manganese
Manganese adds considerably to the tensile strength of steel,...

Heating
Although it is possible to work steels cold, to an extent de...

Furnace Data
In order to give definite information concerning furnaces, fu...

Impact Tests
Impact tests are of considerable importance as an indication ...

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

Hardening Operation
Hardening a gear is accomplished as follows: The gear is tak...

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

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

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

Gas Consumption For Carburizing
Although the advantages offered by the gas-fired furnace for ...

Carbon Steels For Different Tools
All users of tool steels should carefully study the different...



Fatigue Tests






Category: COMPOSITION AND PROPERTIES OF STEEL

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.





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Previous: Impact Tests



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