On Thu, 22 Sep 2016 15:06:26 -0400, Leon Fisk
wrote:

On Thu, 22 Sep 2016 14:17:09 -0400
Ed Huntress wrote:

snip
Did you see that butt-welded tube photo in the Fab Shop article? That
was a certification piece that my welding instructor welded around 15
years ago.It's normalized 4130 welded with 4130 filler -- the
worst-case combination. He's a certified U.S. Air Force airframe
welder, and he has to be re-certified every year.

Anyway, looking at it, and thinking about my own welding
(in)experience, I thought I could break that with one or two hammer
blows. I asked him if I could have it and then I proceeded to beat the
crap out of it.

It wouldn't break. Finally, I got a tiny little crack to show up where
I had folded it over and smashed it some more.

That was a good weld. You might get the tube to crack doing that to it
without any weld area involved...

Right. It tells you something about that chrome-moly 4130, too. In the
normalized condition, which is how most of the tubing is sold, its
strength and hardness are virtually identical to that of DOM 1070. But
the 4130 has twice the elongation (25% versus 12%), so it's much more
ductile.


The whole thing is a series of mysteries. Serious welding instruction
these days includes quite a bit of basic metallurgy. I think that's a
good thing.

If you go back through Jody's videos and info he covers a fair amount
on metallurgy. For people in the trade and serious about welding it is
important, that is for sure.

After watching, reading stuff available on the web today I'm nothing
but an amateur welder, if that. I'm best sticking stuff together with a
MIG and ER70S solid wire in horizontal position. Nothing special...

Me, too.

--
Ed Huntress