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

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

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

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

Carburizing Material
The simplest carburizing substance is charcoal. It is also th...

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

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

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

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

Classifications Of Steel
Among makers and sellers, carbon tool-steels are classed by g...

Rate Of Cooling
At the option of the manufacturer, the above treatment of gea...

Air-hardening Steels
These steels are recommended for boring, turning and planing...

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

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

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

Connecting Rods
The material used for all connecting rods on the Liberty engi...

Gears
The material used for all gears on the Liberty engine was sel...

Chrome-nickel Steel
Forging heat of chrome-nickel steel depends very largely on ...

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

Tensile Properties
Strength of a metal is usually expressed in the number of pou...



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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