Crack problems in welding

[Jerry]

A potential new customer is having problems with their welding source in that many welds are cracking, and evidently there not willing to search out the reason why.

Material is 3/8" 1018 CRS rod with a small plate tacked on about 4" in from each end. The plate is a stamping say 1/8" x 1 x 1 1/2" 1010 CRS.

The plate is case hardened to 50 Rockwell & then Nickel plated before welding, now approximately 15% will develop a crack right threw the center of weld. I don't know what filler or process the other guy is using, yet it seems that no heat is involved and I assume he's using mild steel.

What filler would work best? I would think that ones fighting the fact its case hardened. Maybe a 312 rod. Any thoughts appreciated.

[Pangea]

Case hardened to rockwell 50? If the metal is required to be heat treated to a certain number it is losing it when it's welded. I don't have a good answer for a problem like this.

[BillDaCatt]

I would be wondering why they had it hardened and plated before it was welded. Logic dictates that this would be done last not first.

But I'm sure you are wondering that yourself.

Was the piece quenched after welding, or allowed to cool slowly? You might want to get an unwelded piece and see if there is a difference by allowing yours to cool slowly.

[oilfieldtrash]

Had this happen on a well we drilled in Nevada several years ago. This old oilfield welder was trying to weld a wellhead flange on 8 5/8" csg. He would get his first bead completed and it would crack around the whole bead, he would give it a good cussing, grinding and try again. This happened 3 times before he got it right ( 8 hrs later) and it BOP tested with 500# psi. . This guy was one of the best oilfield welders that I have ever seen (had to put him on standby 4 hrs in advance
to make sure he was sober). We decided that the flange had been used and milled so many times that the hardness was so much greater than the csg, the flange was also thicker. To make a short story long, he finally super pre-heated the flange with a rosebud and was able to run 3 beads inside and out with no cracks! :-)

[greywynd]

A potential new customer is having problems with their welding source in that many welds are cracking, and evidently there not willing to search out the reason why.

Material is 3/8" 1018 CRS rod with a small plate tacked on about 4" in from each end. The plate is a stamping say 1/8" x 1 x 1 1/2" 1010 CRS.

The plate is case hardened to 50 Rockwell & then Nickel plated before welding, now approximately 15% will develop a crack right threw the center of weld. I don't know what filler or process the other guy is using, yet it seems that no heat is involved and I assume he's using mild steel.

What filler would work best? I would think that ones fighting the fact its case hardened. Maybe a 312 rod. Any thoughts appreciated.

Your first line is the one that concerns me. If the customer is not willing to understand/resolve a problem (particularly one that is a 15% failure rate), I would be leary of doing business with them in the first place.

As far as the welding goes, with it being case hardened, there has been an inclusion of carbon in the outer layer of the plate. Think of it this way, it's not 1010 anymore for the thickness of the case, it's more like an H13 or something along this line. I would be tempted to try welding it using a procedure similar to what you would an H13 or another tool steel of similar hardness. This should produce a 'hard' weld, rather than trying to 'mix' the hard and soft materials together. the contact zone between the weld and the 1018 rod will be the one that may develop problems now, but the softer 1018 should be less prone to cracking.

Mark

[usmcpop]

I would question them about what they want in the final product. I simply can't imagine where they are going with this. You may be able to weld it on there eventually without cracking, but will it have the properties that they need when it's done? That's the bottom line.

[Jerry]

First, Yes I too say this is strange to do prior to welding. A tool designer at this manufacturer knows me and brought problem to me, like I said there welding source now so they think is not helping them resolve issue. As stated weld cracks in center usually.

I told him welds looks great. Very nice and small tack is what they are placing down. You can tell there not to hot at all, yet tack is more than fused small filler wire is being addded.

This part after welded is plastic or rubber molded around entire shaft but only to base of the stamped parts. From my understanding stamped plated parts are there for guiding piece into robot prior to molding. I should have parts next week and can post a picture then.
I have 2 different tig rods I use in tool welding for repair. One being 888 good for cracked dies and 312 both have good elongation properties. I'm think I would like to try these on the material.

[Jerry]

First, Yes I too say this is strange to do prior to welding. A tool designer at this manufacturer knows me and brought problem to me, like I said there welding source now so they think is not helping them resolve issue. As stated weld cracks in center usually.

I told him welds looks great. Very nice and small tack is what they are placing down. You can tell there not to hot at all, yet tack is more than fused small filler wire is being addded.

This part after welded is plastic or rubber molded around entire shaft but only to base of the stamped parts. From my understanding stamped plated parts are there for guiding piece into robot prior to molding, and that when molded these parts are held in place by the molded material. The next assembly of parts being added to these parts provides enough strength or (whatever I feel the weld provides strength not plastic ) I should have parts next week and can post a picture then.
I have 2 different tig rods I use in tool welding for repair. One being 888 good for cracked dies and 312 both have good elongation properties. I'm think I would like to try these on the material.

Plastic not a welders best friend

[Engloid]

If its cracking before it gets cooled down, or put into service, I'd bet that it needs preheat. It won't hurt to try it.

[Jerry]

If its cracking before it gets cooled down, or put into service, I'd bet that it needs preheat. It won't hurt to try it.

Thats another option on my table. When parts come in I'd like to try a silicon bronze first.
Pre heating, I guess I could preheat a bunch of parts on my small table top warmer.

[Engloid]

Thats another option on my table. When parts come in I'd like to try a silicon bronze first.
Pre heating, I guess I could preheat a bunch of parts on my small table top warmer.

I would try to weld them with preheat first. If that doesn't work, try the silicon bronze second. I say that because after you put the silicon bronze in there, you may have a **** of a time welding it.

[Jerry]

Ran some samples and here's what I found. Each sample weld test was done with a cooled shaft and when using pre heat , only pre heating case hardened - plated part.

Tig filler Pre heat Hammer test
1) ER70S-2 NO Broke easily
2) Sil Bronze NO Broke but was better
3) 312 Stl. st. NO Broke but was better then both
4) 312 Stl. st 150 degrees Weld held, cracked base metal
5) ER70S-2 150 Same as above


Small pre heat seemed to give good weld and after hammering part back and forth actually started cracking the plated base metal. I may try to up pre heat but if so only enough to where I can handle parts by hand.
__________________

[SND]

I'd try 309L stainless filler.

A weld that cracks in the center can have a few causes. Bad start or bad ending of the weld. Weld possibly not big enough to take the stresses, which can sometimes be solved by making a larger bead. Another way is to stress releave the weld. Preheat will help in that matter although you will lose a lot of that case hardening.

Generaly when I weld hardened steel that won't be put in high heat service and that doesn't need a hardened weld. I use stainless filler.

[uncrichie]

Someone mentioned the possibility of quenching as the problem earlier. Might it be that it was quenched after welding in the hopes of saving or re-establishing the case hardening? Ya never know? Uncrichie...

[Jerry]

I have seen more parts and the cracking is more I think at base of tack, yet also in center. Keep in mind part is only tacked one tack per side.

Here's a pic. of part, it gets two pcs tacked together in center and 1 on each side of center pcs.

Upper pic right side shows one where I hammered back and forth and actually started to crack the small plated base metal about a 1/8" away from my tack.