[TheForge] Re: Splitting steel

[Mike Spencer]

> It sounds like your bar has a rolled inclusion or cold crack from
> being rolled too cold or a fold in the end of the piece that was
> rolled out long enough to take up your bar.


I've never been in a continuous process steel mill so I don't know
where cold shuts might arise there but I have been in an older style
mill.  The open hearth furnace was dumped into a ladle, the ladle
emptied into moulds ca. 2'x2'x10'.  The resulting billet got trimmed
and rolled into a thing about 10"x18" x 20 or more feet long before
going to the main rolling mill.

When I was in the rolling mill, it had shut down half an hour before
because a hot railroad rail had missed a roll and something like 100
yards of rail were snarled like spilled spagetti in, through and under
maybe a half acre of machinery.  While watching the guy with a cutting
torch trying to clean this up, I realized that my foot was getting
warm.  Look down.  There's a little offcut there on the floor near my
foot, 10"x18"x30", still red hot.

This little offcut was, they told me, chopped off the 20'  billet
before starting it into the rolls because the pucker on the end would
get closed up and become a cold shut.  Had a further look at the
offcut and yes, the pucker on the end (from the first size reduction
before going to the main rolling mill) was several inches deep and
held a lot of scale and uidentifiable crud.

A 10x18x30 chunk, if left in place to be rolled out, would make a
*lot* of defective 3/4" round or 2" angle.

- Mike

-- 
Michael Spencer                  Nova Scotia, Canada 
                                 
mspencer@tallships.ca            
http://home.tallships.ca/mspencer/