[exnailpounder]

20160831_175141.jpg (40.89 KiB) Viewed 1819 times

20160831_175127.jpg (47.28 KiB) Viewed 1819 times

I welded this several months ago. Tool steel shaft to a cast steel spade, I used 309l for filler, put in 3 passes, don't remember the amps(it was alot) and it came back today with the weld snapped in the middle. I would have expected the toes to pull out. I should have treated this like a socket weld right? I didn't. I buried the shaft and welded it and I think the weld shrunk up and cracked the weld. What say you? I am going to reweld it and drill and pin it with SS rod. Thoughts?

[Coldman]

Allowing for shrinkage is certainly a good idea.
I question the choice of 304 filler. ER70 wire would be better, if there is a material question then 309 or 312 would work well.
Lastly the size of weld should be the same as the thinner part in this case the tube otherwise the weld will be the weak point. Put more passes in to fill it up.

[Poland308]

I'd have tryed 309 and mind the gap.

[John Chamorro]

pre-heat post heat

[exnailpounder]

I have to edit...my filler was 309l

[kiwi2wheels]

Allowing for shrinkage is certainly a good idea.
I question the choice of 304 filler. ER70 wire would be better, if there is a material question then 309 or 312 would work well.
Lastly the size of weld should be the same as the thinner part in this case the tube otherwise the weld will be the weak point. Put more passes in to fill it up.

Is that a situation where you should also allow the interpass temperature to come down to reduce the shrinkage stress ?

[Coldman]

The shrinkage stress would have risen as a result of the parts being wedged in together prior to welding. If shrinkage movement is allowed for interpass temp shouldn't be a problem.

[noddybrian]

Agreed - looks like shrinkage crack maybe culprit as it's center of weld - looks like weld wetted out nice to parent metal -would have expected crack to start on edge weld / HAZ normally if it was a heat / alloy issue - question - what load is this subject to ? is sideways force is applied - is so unless the two fit perfectly with only 1 weld it will constantly try to flex at that point - I just did a similar thing to help someone out where a CV joint ate the spline off a drive shaft - can only get one weld & that's very difficult due to location under small Kubota tractor - kinda expecting that one back - but it's holding for now - not my proudest job either !

[motox]

just my 2cents.
weld with stringers no weave.
peen between passes.
craig

[exnailpounder]

Agreed - looks like shrinkage crack maybe culprit as it's center of weld - looks like weld wetted out nice to parent metal -would have expected crack to start on edge weld / HAZ normally if it was a heat / alloy issue - question - what load is this subject to ? is sideways force is applied - is so unless the two fit perfectly with only 1 weld it will constantly try to flex at that point - I just did a similar thing to help someone out where a CV joint ate the spline off a drive shaft - can only get one weld & that's very difficult due to location under small Kubota tractor - kinda expecting that one back - but it's holding for now - not my proudest job either !

This is a clay spade for a 90# hammer. It is subject to quite the beating so I thought that just seating the shaft into the spade attachment and welding was all that was needed because it is only subject to force that drives the shaft into the spade. I used 309l for extra strength but as you can see it cracked in the middle. Shrinkage crack, But now here is the poser...If I would have left a small gap, like you would for a socket weld, and the weld didn't shrink enough to seat the shaft entirely, it probably would have cracked or ripped the weld out by the toes because of the force it receives.
I am going to grind everything off and undercut as much as I can to get better penetration and then drill it and weld in a SS pin. I think that will do it. I'll post up the end result.

[motox]

jeff
any way you can machine a sleeve on the
shaft then inset the shaft (leaving slight gap against the cast piece)
and weld the thicker sleeve to both?
just a thought...
craig

[exnailpounder]

jeff
any way you can machine a sleeve on the
shaft then inset the shaft (leaving slight gap against the cast piece)
and weld the thicker sleeve to both?
just a thought...
craig

No machining capabilities craig...that is a good idea though. I think when I re-weld it, I am going to do the first pass with ER70s2 and the cover passes with 309l. Hopefully that first pass will hold it in place so the 309 won't shrink and crack again. I learned a lesson here. What I thought was just a quick little weld job came back to bite me because I wasn't paying attention.
That was kind of why I posted this. Sometimes we have to take a really good look at something before we just weld it. I think I can outsmart it this time

[exnailpounder]

I just did some research as to what metal this is. It is 42CrMo heat treated Chinese tool steel. The American equivalent is 4140. From what I read 4140 HT is not recommended for welding.

[noddybrian]

Only ever seen clay spades drop forged from a single piece here - I'm guessing there's a reason ! & quality Chinese material as well - now what can possibly go wrong ! good luck with it.

[soutthpaw]

I just did some research as to what metal this is. It is 42CrMo heat treated Chinese tool steel. The American equivalent is 4140. From what I read 4140 HT is not recommended for welding.

This might be one you have to eat the cost. Maybe grind it all clean and refund the customer explaining that the Chinese crmo is not supposed to be welded. Or offer to weld it back up after explaining the issue and tell them it's a no warranty job....

[exnailpounder]

I just did some research as to what metal this is. It is 42CrMo heat treated Chinese tool steel. The American equivalent is 4140. From what I read 4140 HT is not recommended for welding.

This might be one you have to eat the cost. Maybe grind it all clean and refund the customer explaining that the Chinese crmo is not supposed to be welded. Or offer to weld it back up after explaining the issue and tell them it's a no warranty job....

I told him the problem and I am going to refund him his money. He understood. I thought the pin idea would work but you can't even scratch this shit with a drill bit so he is on his own.

[noddybrian]

Just a random thought ( now you decided not to do it ! )- if you were to try it pure nickel might just work - sticks to about anything & is very forgiving on movement when cooling - hence why it's used on cast - or something with high nickel like " super missile " - still unclear why it's made in 2 parts or is it a modification to put a clay spade end onto a different shank for which they are'nt available ? seems like something under that much shock / vibration is not ideally suited to welding - bit like when you try to weld stuff onto machine breaker shanks for improvised ( redneck ) pile driving etc.

[exnailpounder]

Just a random thought ( now you decided not to do it ! )- if you were to try it pure nickel might just work - sticks to about anything & is very forgiving on movement when cooling - hence why it's used on cast - or something with high nickel like " super missile " - still unclear why it's made in 2 parts or is it a modification to put a clay spade end onto a different shank for which they are'nt available ? seems like something under that much shock / vibration is not ideally suited to welding - bit like when you try to weld stuff onto machine breaker shanks for improvised ( redneck ) pile driving etc.

I threw in the towel on it. My friend who is a boilermaker agreed that with the punishment it is going to take, it's best to pass. I have no friggin idea why they made this thing in two pieces that won't stay together when you use it. It must be a Chinese design. I was going to try some Inconel rod on it but then I thought that if that didn't work, I might brittle the spade out and it might shatter. The whole deal set the guy back over $300 so that's not something I want to replace when I can walk and give him his $30 back. He is going to try to drill it and use a grade 8 bolt to hold it together. Hope he has alot of money for drill bits

[nelson]

Air hammer eh? Yeah give his $$$ back and walk.

Or try some tool steel drill rod for filler. I did that to put a hard edge on some mild steel. I used soft A2 which only draws back to 58 Rc. For an air hammer you need to get below that. If you could get S7 (shock resistant air-hardening) I'd say try it. Is that taper really snug? Any flexing would surely kill your joint.

Nice wholesome topic.

88595K201 from mcmaster-carr 3/32 pricey though.

[GreinTime]

You can use piston rings in a pinch if you need a high nickel filler just for reference.

Sent from my SM-G900V using Tapatalk

[maker of things]

Ex, I think you made the right call on this one. If the guy asked you to try and understands that it might not work maybe it would be a different story. But if you are liable to replace the part, I wouldn't want to take on that risk either. Your customer is not out anything more than before he came to see you so that should not leave a bad taste in his mouth.

[ex framie]

I learned a lesson here.

So did I thanks for posting.
Bear in mind the way this would have been used, drive into clay, then apply full bending force to lever out the chunk of clay, rinse and repeat. You were on a hiding to nothing from the start.
First question I always got from the aircraft welders I took stuff to for repair was "what's it made from"?
Great question eh.
Cheers

[nelson]

Seems that if it wasn't a solid well fitting taper, all you did was weld an inflexible hinge. How about grinding 4 holes in the casting near the end of the taper and fuse the shafts down there as well?
Some people do crossword puzzles, I like engineering puzzles better.

[exnailpounder]

Seems that if it wasn't a solid well fitting taper, all you did was weld an inflexible hinge. How about grinding 4 holes in the casting near the end of the taper and fuse the shafts down there as well?
Some people do crossword puzzles, I like engineering puzzles better.

UPDATE>>>>The guy begged me to re-weld it for him SO....I was going to use Inconel but after reading more about it,,,I decided on ER80S-D2..highly recommended for chromoly. I pre-heated it to 500 degrees+ and then poured the coals to it. I did 4 passes and didn't use a ton of filler because I was worried about shrinkage again. After I welded it, I wrapped it in some pipe insulation and after 4 hours I still burnt my hand on it so I waited another 2 hours to unwrap it. He just left with it 5 minutes ago. I told him I feel better about the filler metal I used this time and I think he is going to have better luck this time. As far as drilling it...I tried to bore a 1/4" hole for a grade 8 bolt and I couldn't even scratch it with a cobalt bit. My buddy at the machine shop said he would bore the hole but the guy needs it for Monday and I can't get it done so I told him to cross his fingers....and theres always JB WELD and duct tape

[ex framie]

Love a challenge eh?

Keep us posted if it comes back, or not.
Cheers