Heat
Treating In WeldingI tell my students
what they learn in my welding classes is the tip of the iceberg when it comes
to knowledge of the welding trade. And when I say tip, I mean a very small tip
at that. Some people think of the welding trade as some guy standing there all
dirty with a stinger in his hand and a cig hanging out of his mouth and that's
it. Ahhhh grasshoppers, those people
don't have a clue about the vast amount of knowledge there is when it comes to
welding applications, processes, metallurgy, and theory.
I'm
going to cover one of those practices here in laymen's terms, and will probably
need a couple of more articles to do it. Heat treating steel can be a very important
part of welding and is many times not done right, if at all. Most construction
steel I worked on in Texas didn't need it unless it was in the Panhandle where
it can get really cold. When I think
of heat treating, I think of a job a few years back in Dallas, Texas where Iron
Workers were having to heat treat these huge girders at the Penny's corporate
headquarters. Unsuspecting "boomers" (travelers from other Iron Worker
Locals around the country) would come in and be sent to the job as a heat treater.
Heck, it's a job most of us hadn't done and it sounded interesting and pretty
easy. When they got to the job they found
the steel they would heat treat was big ol' girders that needed to be heat treated
before they were welded. In this case I believe it was to between three and four
hundred degrees. It was summer and if you've been to Dallas in summer, you know
it is hot! It was well over 100 degrees out with excessive humidity and they had
to heat treat the steel with huge torches that put out a LOT of fire. It
was brutal, and most guys worked long enough to get their first paycheck before
they were out of there. One guy told me that when they called out for heat treaters
at the union hall it looked like someone had thrown a hand grenade in there after
word had gotten out about the job. I
can't remember exactly why they needed to heat treat the joints to be welded except
that it was a new type of steel they were using, and I would suspect it was because
of alloys added to it. Some of the alloys would perform better in the finished
weld if they were already three or four hundred degrees before the welding arc,
which can be around 6500 degrees F, started to fuse the filler metal to the parent
metal. My definition of heat treating
is bringing the heat of the steel or metal to be welded up to a specific temperature
to accomplish certain properties. See Heat
Treating - Part 2.
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