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109.02
In chrome-nickel-steel, the primary constituents are
iron, chromium, and
nickel. There are minor constituents of carbon, manganese,
and others. It is a very popular
way of thinking to say that a chain is no stronger than
its weakest link. That seems to be
very logical to us. Therefore, we feel that we can predict
things in terms of certain minor
constituents of wholes. That is the way much of our
thinking goes. If I were to say that a
chain is as strong as the sum of the strengths of its
links, you would say that is silly. If I
were to say that a chain is stronger than the sum of
the strengths of all of its links, you
might say that that is preposterous. Yet that is exactly
what happens with chrome-nickel-
steel. If our regular logic held true, then the iron
as the weakest part ought to adulterate
the whole: since it is the weakest link, the whole thing
will break apart when the weakest
link breaks down. So we put down the tensile strength
of the commercially available
iron__the highest that we can possibly accredit is about
60,000 pounds per square inch
(p.s.i.); of the chromium it is about 70,000 p.s.i.;
of the nickel it is about 80,000 p.s.i. The
tensile strengths of the carbon and the other minor
constituents come to another 50,000
p.s.i. Adding up all the strengths of all the links
we get 260,000 p.s.i. But in fact the tensile
strength of chrome-nickel-steel runs to about 350,000
p.s.i. just as a casting. Here we
have the behavior of the whole completely unpredicted
by the behavior of the parts.
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