On Fri, 23 Jun 2017 16:49:40 -0500, Terry Coombs
wrote:

On 6/23/2017 10:18 AM, Ed Huntress wrote:
On Fri, 23 Jun 2017 10:59:32 -0400, Ed Huntress
wrote:

On Fri, 23 Jun 2017 10:49:28 -0400, Tom Gardner
wrote:

On 6/22/2017 5:11 PM, 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

I might be tempted to braze it.

Brazing would work. Welding any 4130/40 that thick is going to need
pre-heat and, probably, post-heat.

Here's an article on welding 4130 that we published last year. It took
me a year to squeeze this article out of the experts. I was frustrated
for years by the vast amount of bull that's been published about
welding 4130, and I finally got to the right guy at Hobart:

http://magazine.fsmdirect.com/2016/sept/d/#page7
BTW, on page 10, in the black-box sidebar, where it says 0.65 in.,
read 0.065 in.

I wrote that but it was final-edited just after I retired, so I never
had a chance to catch that one.

Excellent ! Tells me what I needed to know to make this a lasting
repair . Preheat to ~450-500° , weld with 7018 , and slow cooling looks
like the best way to get a solid weld with small chance of stress
cracking . BTW , at some point someone corrected that .65/.065 mistake .

Thanks !

--

Snag

Great, Terry. Let us know how it works out.

--
Ed Huntress