# Filler Metal for Unknown Tool Steel?



## Weldo (Jun 20, 2020)

Hey, I'm seeking advice on filler selection for a part from an Atlas shaper.

There's a pin pressed into a plate.  The back side is welded and ground flush.  

In the pic below I've already begun pressing it out.  The flushed off weld had cracked around 90% of the circumference.





The front side receives no weld.





The pin is most likely some kind of tool steel.





I'm not sure about the plate being tool steel.  It probably should be for the service it does, but none of the surfaces are finished as finely as the pin.  Some scoring can be seen in the sliding fit parts so it may not be a very hard steel.





In the little research I've done some have suggested specialty tool steel rods.  Others say 309L is a good choice.  Some have said 7018.  Most agree that pre/post heating and ample peening is a good idea.  I've even heard that you could avoid all the metallurgical intricacies by brazing instead of welding when it comes to tool steel.

So what are your thoughts?


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## b4autodark (Jun 20, 2020)

Kind of a poor design for a weldment in my opinion, but it is what it is.  I would try to chamfer the back side of the plate until all the original filler material is gone so you won't be dealing with that as well and to give your new weld more surface area, also dress off the end of the pin.

Pre and post heating is a good practice for a "unknown material procedure" like this especially to prevent cracking of the weld which in my experience is more likely than with a straight line fillet weld. Stress relieving is also recommended.

A plug weld with a 3/32" 309L electrode at 90 amps would be my choice. 

Good luck.


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## General Zod (Jun 20, 2020)

Other good choices are Harris 03SMW  Super Missile Weld TIG rod, and Hastelloy-W.  I could sell you small quantities of either rod if you wish.


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## Weldo (Jun 20, 2020)

Oh, a dealer, eh?

I may take you up on that.  Over in the shaper section there's at least one other guy who had this same problem with old weld cracking.  Maybe it's a common problem but I'd like to ensure I don't have it again later on.


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## Ulma Doctor (Jun 20, 2020)

don't forget about E312 !


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## General Zod (Jun 20, 2020)

Weldo said:


> Oh, a dealer, eh?
> 
> I may take you up on that.  Over in the shaper section there's at least one other guy who had this same problem with old weld cracking.  Maybe it's a common problem but I'd like to ensure I don't have it again later on.



ER312 is also a good choice.

No, I'm not a dealer of anything.  I just happen to have lots of stuff.

I have (in various sizes)

Hastelloy-W
Hastelloy-X
ER312
ER309L
ER308L
ER321
ER347
ER70S-2
Inconel-625
ERCuSi-A
Super Missile Weld
ER4043
ER5356
ER4943
ER-Ti-5 6Al-4V
ER-Ti-23 6Al-4V ELI
ER80SD-2
Inconel 718 (on-order)
Inconel x750 (on-order)


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## Lo-Fi (Jun 20, 2020)

I'm currently having really good results TIG brazing unknown tool steel. Knowing now how easy it is, I'd put some hefty prep chamfers in and get brazing - tig or otherwise! You can probably get a stronger joint than original if you're cunning with the prep


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## Weldo (Jun 20, 2020)

General Zod said:


> No, I'm not a dealer of anything. I just happen to have lots of stuff.



Thanks for the offer, man!  I'll definitely file that away for future!



Lo-Fi said:


> I'm currently having really good results TIG brazing unknown tool steel. Knowing now how easy it is, I'd put some hefty prep chamfers in and get brazing - tig or otherwise! You can probably get a stronger joint than original if you're cunning with the prep



This was something I'd run across in my searching.  You can avoid some of the drawbacks of welding by not actually melting the base metal.  I may give that a try.  I bought some brazing rods years ago but never played with 'em.  Now's the time I guess.  I forget what type they were...


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## rwm (Jun 20, 2020)

Be careful. I find it very hard not to melt any base metal with TIG braze. I have had some very weak bonds. Torch brazing is more reliable if you have a torch hot enough. Personally, I would just TIG weld it.
Robert

Jodi says it here:








						TIG Welding/Brazing with Silicon Bronze
					

Video on Tig welding/brazing using sil-bro - silicon bronze filler rod



					www.weldingtipsandtricks.com


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## Weldo (Jun 20, 2020)

I've never actually TIG brazed but I expect there to be a very fine line between getting the base hot enough but not melting.  I'll try it out on some scraps first.

Thanks for the advice.  It seems to be a poorly designed part that is prone to cracking so I want to do the best repair possible.  The pin only presses in about 0.250" or a little more and it's under heavy load.


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## Lo-Fi (Jun 21, 2020)

I reckon it's the safest option 

Careful if you're trying TIG. If the unknown rods contain zinc, they'll just explode and make a mess! Found this out when I went to try, thinking "great, I've got some brazing rods". Made a horrid mess. After getting the right rods, I was surprised how easy it was despite my inexperience with TIG. Move fast, short arc, don't be afraid to pull not push, it's actually much easier to feed the rod onto the hot metal while the torch is heating the next spot than running into the rod. Flies in the face of all TIG welding wisdom, but it is a different process, after all!


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## Old Mud (Jun 21, 2020)

That doesn't look like decent penetration on that pin. There are good options on welding or brazing but if it were me i would get a chunk of 4140 and make new. Then chamfer the pin and the plate (30 degrees each) and weld with something softer like 309 L or 316 L.  JMHO

  I think those marks on the underside are grind or file marks from someone trying to down a proud weld.


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## Weldo (Jun 21, 2020)

I'm starting to reconsider the brazing.  I watched Jodi's vid posted above by @rwm and there's possibility of cracking if some base metal gets melted in with the brass.  Also since my part requires a butt joint, it's not ideal for brazing.  Braze seems best suited for fillets and laps.


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## rwm (Jun 21, 2020)

I agree with Old Mud- there is poor penetration with almost no penetration of the pin. Then they ground down the weld until the actual joint was very thin. Technically that is not a butt joint. It would braze fine with proper flux and heat and there would be no risk of distortion. If a small amount of warp would be critical to that part then gas brazing is the way to go.
Robert


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## Lo-Fi (Jun 21, 2020)

Silver solder might also be a good way to go as it'll wick right through the joint. Agreed that the original method of popping a weld bead over it then grinding most of it off was not great. I'd heavily V it if welding or brazing it.


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## Weldo (Jun 21, 2020)

I will chamfer the hole a good bit and bevel the pin.  



rwm said:


> If a small amount of warp would be critical to that part then gas brazing is the way to go.



You think using a torch will result in less distortion?  Distortion is a concern on this machined part.



Lo-Fi said:


> Silver solder might also be a good way to go as it'll wick right through the joint.



Will silver solder wick into a tight press fit?


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## pontiac428 (Jun 21, 2020)

My vote is on TIG welding the dissimilar steels with SS.  I think you should be able to heat sink the base well enough that you could complete the TIG joint with less time and less total heat input than brazing.  A SS join on dissimilar steel is a very strong joint.


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## Weldo (Jun 21, 2020)

Did some prep on the part.  I beveled the pin no problem but when countersinking the hole my single flute c-sink cut a little then just started rubbing.

I got some of the weld out but not all.  I was still able to file the old weld so it's not super hard.





A little bit of the old weld is still there on the left side of the hole.





Looks like penetration should be adequate.  The V groove is almost half the thickness of the plate.  If the countersink was able to cut I'd probably go a little further.


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## ericc (Jun 22, 2020)

That base looks suspiciously like cast iron.


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## pontiac428 (Jun 22, 2020)

ericc said:


> That base looks suspiciously like cast iron.



Now that's a scary thought.  But if you look at the first pair of pictures, you'll see ballies stuck to the base piece near the mating of the two parts in question that probably got there when they welded them together in the first place.  It could be a friction weld, a resistance weld, or a plug weld, I don't know, but I'm betting that this is not cast iron and can be welded normally.


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## rwm (Jun 22, 2020)

I think welding with the amount of fill rod needed to fill that bevel is going to pull the machined sides of the part "up." The part will end up bowed away from the pin. I don't think this will happen with brazing, at least not to the same extent.
Robert


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## Weldo (Jun 22, 2020)

Hey y'all, heads up on an apparently super good deal over on ebay.  1-lb of 3/32" Hastelloy-W rods for $43.99

ebay

This is a great price for these rods!  I picked up a pound for myself.  Might be good to have some stored away for special cases.

As far as the piece being cast, I do not think it is.  The way is grinds, files and looks up close seems to be plain mild steel.  On the one unmachined face you can almost make out ancient mill scale.  Also the piece measures about 0.495" in thickness which tells me they just started with a 1/2" flat bar and cleaned up one side.  Just a guess though.

I probably won't try to fill the V groove completely.  If it ends up a little concave that would be fine.  I wanted good penetration, hence the deep/large groove.  I'll have it clamped tight to a big aluminum heat sink for welding.


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## rwm (Jun 22, 2020)

Just for fun put a straight edge on the pin side and see how flat the face is before and after welding. 
Robert


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## Weldo (Jun 27, 2020)

Here's what I came up with...

I clamped the part on a big aluminum block with another copper plate butted right up on the underside of the pin.  This plate just happened to have a big hole in it the straddled the pin nicely.




To keep pressure upwards on the pin I used a small arced piece of copper plate.  It acted like a leaf spring to hold the pin in place.





For the actual welding I swapped the spring clamps for vice grip pliers.  I hit it with a MAPP gas torch for a few minutes for a little pre heat then welded around the groove with a 3/32" Hastelloy-W rod.  In hindsight I could've used a 1/16" rod probably and the weld would've been a little more concave.  

After the weld was laid in I went back over it with a somewhat hotter weave to flatten it out.





I came out pretty flat to slightly concave which is what I was hoping for.





I tried to do a nice tapering out on the finish.





After welding I hit it with a MAPP torch a little bit to help it cool more slowly.  It doesn't seem to have warped at all but we'll see when it's unclamped.  Fingers crossed!

Thanks for all the advice guys!  I guess I won't know if this is a good repair until it's seen some service.


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## Lo-Fi (Jun 27, 2020)

Nice job!! 

I'm really getting to grips with TIG brazing. Finding it very useful


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## brino (Jun 27, 2020)

It looks great!
-brino


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## rwm (Jun 27, 2020)

That looks really great. I'm sure that weld is very solid. Can you tell if you got any warp at all on the pin side?
Robert


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## Weldo (Jun 27, 2020)

It's kind of hard to show in a picture but there does not appear to be any warpage.  Holding a 6" scale as pictured I cannot pass a 0.0015" shim underneath it.  I also checked it across the other way, perpendicular and it seems flat.


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## General Zod (Jun 27, 2020)

Awesome work!


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## DavidR8 (Jun 27, 2020)

Well done!


Sent from my iPhone using Tapatalk


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## Weldo (Jun 27, 2020)

Thanks!  I really appreciate all the advice!


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