On Sun, 25 Jun 2017 07:11:11 -0500, Terry Coombs
wrote:

On 6/25/2017 1:30 AM, Gunner Asch wrote:
On Thu, 22 Jun 2017 16:11:48 -0500, Terry Coombs
wrote:

One of the locals brought me a part from his brush hog , it's the
pivot yoke that carries the rear wheels (I think) . The sleeve that fits
it to the pivot pin on the body of the machine is worn , and had broken
the weld on one side , sleeve was split most of the way up .

I'm machining him a sleeve from some 4140-type (acts/welds/spark
tests/hardens just like 4140 but ...) and I will be welding it to the
angle iron frame of the yoke . I can either arc weld it with 7018 or
6013 or I can TIG weld it with ER70S2 (or 308 or 309 SS) - my baby MIG
ain't got the ass for something this heavy . I know they TIG 4130/4140
tube for chassis's , but that's a lot thinner cross section . This part
will be ~1.250" ID x 4.5" long with about a .625 wall thickness , the
original had a 3/16" wall . I don't want to have this thing fail because
of a HAZ failure ... I'm thinking I might need to preheat (after tacking
in place) then control cooling to avoid localized hardening . Thoughts ,
opinions (about the job!) your experiences in the same/similar situation
welcomed . If you think I'm an idiot for taking this on , keep it to
yourself ...

--

Snag
Stick weld it with 6011 with 6013 as a distant second choice.

You can TIG it..but you will need about 225 amps to do it properly
with TIG

Preheat to about 500F...if you feel the need.

Does it make any difference how hard this gets when its cool? This is
not a part that is going to see a lot of sudden flexing....

Only as relates to shock loads and it's likely to see a lot of that .
If it's brittle it's more likely to fail ... moot point because I welded
it yesterday with around 500-600° preheat , welded with 7018 then held
at the same temps for about 30 minutes after welding and cooled it
slowly . When it cooled I checked and it can be cut with a file - sleeve
and weld both . Just what I wanted .

Excellent job, Terry.

--
The Federal budget is a complex document. However, working
for a President committed to keeping his promises means my
job is as simple as translating his words into numbers.
Mick Mulvaney, Director OMB on Trump