On Thu, 18 Jul 2013 17:05:58 +0000 (UTC), David Lesher
wrote:

Ed Huntress writes:


FWIW, railroad rails are made of hypereutectoid (excess carbon)
pearlitic steel that work-hardens to around 500 Bhn -- equivalent to
50 - 52 Rockell C -- in service. New, as-rolled, it's typically 400 -
430 Bhn.

And what I recall learning as a child....the reason there are
so many wheels around a rail yard is they are deliberately made
softer than the rails; wheels are easier to replace...

A long-dead machinist friend once found some OLD two-piece rail
sticking out of the ground. He cut off pieces and donated them
to a museum in Pennsylvania. ISTM he said they figured out they
were Civil War era.

Rolling rails was a real challenge in the early days. At the beginning
of rail, they were wooden rails with wrought-iron strips on top. Then
there were a couple of interim steps -- I think the two-piece was one
of them -- as steel mills developed the capacity to roll the kinds of
rails we have today.

It was a major impetus to the development of steelmaking and
rolling-mill work. Like firearms and steam power, the demand for rails
was a primary motivating force that drove the modernization of several
metal producing and metalworking industries.

--
Ed Huntress