On Sat, 24 Jun 2017 15:18:10 -0500, Terry Coombs
wrote:

Well , I got the bush hog pivot bracket repaired , and it's cooling
slowly . I'm not sure just how hot it got , my IR thermometer wouldn't
read it . Not red hot , but not far off either . Welded it with some
7018 then put the heat back on it for another 20 minutes to be sure it
was uniformly hot , then packed it in firebricks and fiberglass
insulation to cool slowly . I did a check for distortion , I have a slug
that was a just-slightly-loose fit that dropped thru quite nicely . I
did contact the guy before I welded it together to ask about the pin it
rides on , he said the pin is not worn at all .

--

Snag

Let's hope it holds together. I'll bet it will be perfectly fine.

Although there is an entire mythology about welding 4130, it's really
relatively ductile, which makes it more forgiving that many people
think.

As I said in that article, the reason 4130 leads to so much
head-scratching is that it's *very* slow-quenching. In thin tubes,
which are almost always welded in the normalized condition, it can
wind up quench-hardened from welding. It actually will air-harden.
That's why it was two decades before TIG welding it was accepted. It's
only recently (the last couple of decades) that MIG welding has met
the approval of the "experts." Stick is similar.

Sections as thick as you're welding generally don't experience that
quench-hardening problem, but the quench characteristics can produce a
very confused HAZ. That's why the pre-heating and the slow cooling.
Every authority I've talked to over the last decade or so says that's
all it takes.

--
Ed Huntress