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Correction By Zero Adjustment
Many pyrometers are supplied with a zero adjuster, by means ...

The Modern Hardening Room
A hardening room of today means a very different place from ...

Optical System And Electrical Circuit Of The Leeds & Northrup Optical Pyrometer
For extremely high temperature, the optical pyrometer is lar...

Annealing
There is no mystery or secret about the proper annealing of d...

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

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

Mushet And Bessemer
That Mushet was "used" by Ebbw Vale against Bessemer is, perh...

Forging High-speed Steel
Heat very slowly and carefully to from 1,800 to 2,000 deg.F....

Cutting-off Steel From Bar
To cut a piece from an annealed bar, cut off with a hack saw,...

Chromium
Chromium when alloyed with steel, has the characteristic func...

Hardening High-speed Steels
We will now take up the matter of hardening high-speed steels...

High-chromium Or Rust-proof Steel
High-chromium, or what is called stainless steel containing f...

Case-hardening Treatments For Various Steels
Plain water, salt water and linseed oil are the three most co...

Heating Of Manganese Steel
Another form of heat-treating furnace is that which is used ...

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

Calibration Of Pyrometer With Common Salt
An easy and convenient method for standardization and one whi...

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

Properties Of Alloy Steels
The following table shows the percentages of carbon, manganes...

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

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



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.





Next: Hardness Testing

Previous: Impact Tests



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