Welding 4140 to mild steel

[Ignoramus3543]

For my new heavy shop press

http://goo.gl/1XGhQ

I wanted to make an end piece for the hydraulic ram, so that the ram
is enclosed inside the nose piece. This way, I hope, I can aviod
deforming the valuable ram, and instead would expose a cheap end piece
to all the deformations.

To that end, I grabbed a piece of 4140 structural tube, appx. 5
inches ID, 1/2" inch thick, and a mild steel round bar appx. 6.5
inches in diameter (a bit wider than the tube) and 1 inch thick.

After boring the tube a little bit so that it would fit over the ram,
I welded the round to one of the ends of the tube. I used 3/16" 7018
welding rod at 180 amps.


Side view:

|! !|
.|! !|.
=============

The dots "." above signify the weld area.

It ended up looking half way decent. There was some intentional
clearance between the inside of that tube and the ram, and I filled it
with a rag (put a rag on top of the tube and pressed down with the
ram, pulling the rag in as the ram went). The rag holds everything
together and, I hope, will also provide some cushion and ease of
removal.

And then I started doubting myself, about how well that weld is going
to hold up to pressing at 75+ tons. 4140 is medium carbon and how well
is the weld going to hold, in this scenario?

And, most importantly, if it fails, under pressure, how it is going to
fail? If it just cracks, then nothing unsafe is going to happen. Just
a little embarrassing. But could it shatter violently?

Supposedly, when pressing, the stress on the weld is not going to be
much, as the pressing force is passed down from the ram, and the rag,
to the bottom steel round. The tube is just there to keep everything
together.

Any opinions will be appreciated.

thanks

i

[Steve W.]

Ignoramus3543 wrote:
> For my new heavy shop press
>
> http://goo.gl/1XGhQ
>

SNIP

> Any opinions will be appreciated.
>
> thanks
>
> i

Shouldn't be a problem. The load should be evenly spread across the surface.

--
Steve W.

[Wild_Bill]

Not many jobs will require the full 75T capacity of the press.. I'd expect
most jobs to be significantly lower.

I'm no metallurgist, but a piece of steel that can be bent without snapping
will just deform under stress/tension. There could possibly be some reason
for concern if working with work hardening stainless alloys.

Unless you try pressing endmills or other hard cutting tool steel into other
parts, there should be no shattering, or flying bits breaking away from the
workpieces.

--
WB
.........


"Ignoramus3543" <ignora...@NOSPAM.3543.invalid> wrote in message
news:e82dnbEpGbfNmQrM...@giganews.com...

[John B.]

As you describe it there will be essentially no force on the weld as
the ram will press against the mild steel which will press against the
work (if I read your description correctly :-)

--
Cheers,

John B.

[Lloyd E. Sponenburgh]

Ignoramus3543 <ignora...@NOSPAM.3543.invalid> fired this volley in
news:e82dnbEpGbfNmQrM...@giganews.com:

> And then I started doubting myself, about how well that weld is going
> to hold up to pressing at 75+ tons. 4140 is medium carbon and how well
> is the weld going to hold, in this scenario?

What's to fail? The ram pushes on the plate, not the tube. The tube is
only providing positioning and retention for the plate.

Were I you, I'd nix the rag between plate and ram. You can put three
setscrews around the tube to hold the plate in place. The rag consitutes
"cushion", as you noted. Anything that can absorb energy and spring back
suddenly when released is bad to have around hydraulic presses.

Lloyd

[dca...@krl.org]

On May 18, 7:47 am, "Lloyd E. Sponenburgh"

<lloydspinsidemindspring.com> wrote:

> Were I you, I'd nix the rag between plate and ram.  You can put three
> setscrews around the tube to hold the plate in place.  The rag consitutes
> "cushion", as you noted.  Anything that can absorb energy and spring back
> suddenly when released is bad to have around hydraulic presses.
>
> Lloyd

I agree with Lloyd but for somewhat different reasons. I think you
will get some distortion in the ram anyway and having a close fit
will make it hard to take your weldment offi So I would put some set
screws in the tube. I would only put in two set screws spaced about
60 degrees apart. And drill a slight bit into the ram where the set
screws contact the ram so the set screws will not distort the ram and
make it hard to remove. When you put it together put some wax in the
hole so the ram and tube will not rust. And make sure the ram is not a
close fit in the tube.


It would be better if the plate was 4140 and the tube was mild steel.
The force will almost all on the plate.


Dan

[Ignoramus12664]

On 2013-05-18, dca...@krl.org <dca...@krl.org> wrote:
> On May 18, 7:47?am, "Lloyd E. Sponenburgh"
><lloydspinsidemindspring.com> wrote:
>
>> Were I you, I'd nix the rag between plate and ram. ?You can put three
>> setscrews around the tube to hold the plate in place. ?The rag consitutes
>> "cushion", as you noted. ?Anything that can absorb energy and spring back

>> suddenly when released is bad to have around hydraulic presses.
>>
>> Lloyd
>
> I agree with Lloyd but for somewhat different reasons. I think you
> will get some distortion in the ram anyway and having a close fit
> will make it hard to take your weldment off

And that is why my fit is far from close, and exactly why I use a rag,
to fill a space with soft material, keep the nose in place, and
provide minimal cushioning.

I thought a lot about Lloyd's comment about cushioning providing some
undesirable spring action, but, I think, a rag should not be able to
store any significant energy.

> So I would put some set screws in the tube. I would only put in two
> set screws spaced about 60 degrees apart. And drill a slight bit
> into the ram where the set screws contact the ram so the set screws
> will not distort the ram and make it hard to remove. When you put
> it together put some wax in the hole so the ram and tube will not
> rust. And make sure the ram is not a close fit in the tube.

Yes. The cylinder is double acting, so I think that I will be able to
pull it out of the nose piece, if I ever need to.

As for set screws, I am afraid that they will get damaged by the
pressing action and "play".

>
> It would be better if the plate was 4140 and the tube was mild steel.
> The force will almost all on the plate.

I agree with that, I used what I had available, not saying that it is
the best selection.

i

[Steve W.]

One thing I just thought of, Are the faces of both sides of the plate
parallel? You don't want the face to be angled in any direction while
your using the press. Not a good thing for precise work.

--
Steve W.

[Ignoramus12664]

On 2013-05-18, Steve W. <csr...@NOTyahoo.com> wrote:
> One thing I just thought of, Are the faces of both sides of the plate
> parallel? You don't want the face to be angled in any direction while
> your using the press. Not a good thing for precise work.
>

Yes, the plate was cut out from a hot rolled plate, it looks like.

i

[alv...@example.com]

> ...the plate was cut out from a hot rolled plate, it looks like.
> i

Cool. :)

Prob'ly 100% right too! :)

Spark test it and you'll know-more. ;)

I was given some hot rolled steel that's new-old-stock VascoWear.
(type 421 tool steel, type 420 = A2)

Bought some hot rolled steel that was D2 Tool steel.

Igno, I know you from the blacksmithing newsgroup, please learn
how to spark test?

Please? ;)

All you need are a few known samples.

Alvin in AZ

[Ernie Leimkuhler]

Normally, to weld 4140 to Mild steel you would use a stronger rod, like
8018. You should also have preheated the whole piece to around 500 degF
before welding and allow to slow cool under sand or some other
insulator.

I doubt anything will explode.
All the force is on the mild steel, however your welds will likely
crack eventually. No big deal. Just grind out the cracks and reweld.

The rag will likely decompose over time and pressure into powder.





In article <e82dnbEpGbfNmQrM...@giganews.com>,

[Ignoramus12664]

On 2013-05-18, Ernie Leimkuhler <er...@stagesmith.com> wrote:
>
> Normally, to weld 4140 to Mild steel you would use a stronger rod, like
> 8018. You should also have preheated the whole piece to around 500 degF
> before welding and allow to slow cool under sand or some other
> insulator.
>
> I doubt anything will explode.
> All the force is on the mild steel, however your welds will likely
> crack eventually. No big deal. Just grind out the cracks and reweld.
>
> The rag will likely decompose over time and pressure into powder.
>

Ernie, thanks a lot, I will be using it and will reweld as necessary.

i

[Private]

"Ignoramus3543" <ignora...@NOSPAM.3543.invalid> wrote in message
news:e82dnbEpGbfNmQrM...@giganews.com...

IMHO, ANY heavy press should be equipped with a substantial screen which is
permanently attached to the press frame and can be positioned to prevent any
flying shrapnel from striking any persons or property. The screen should be
able to be moved aside (or up) to load the work into the press then easily
positioned to contain any possible shrapnel caused by the failure of the
press, its attachments or jigs or of the work. The positioning of the
screen should be done before ANY substantial pressure is applied.

Some would suggest that the screen should be equipped with a micro switch
that prevents application of substantial pressure without the screen being
locked into place, but most workplaces just have a sign requiring the use of
the screen. I suspect that a screen is a requirement of OH&S / OSHA.

"Protect yourself at all times" is not just for boxers.

Good Luck, YMMV

[Ignoramus17710]

i do have a screen on my press, check the picture above