Cracking welds

[Welderpaul]

Last week fabricating some machine stands. 40mm solid square 316 posts onto 20mm thick 316? 300 square plates.
As per the spec provided, they were welded on four sides, 8mm FW using 3.2 316L rods. Rods nothing special, not white box, but not great. Four tacks, then ploughing in the weld.
Once the welds were completed, the parts were put on the floor to avoid flying slag. There was an almighty bang, and one of the parts had split apart, The weld was still attached to the posts, but has come clean off the baseplates. Almost as if the weld had not penetrated into the plate. I know it should have done, it's not operator error

The second one didnt break, but when belted with the hammer, that one too fell apart.

Parts were supplied to us ready for welding. Any ideas what the baseplates could have been cut from? They certainly look like stainless Seems strange that the first would blow apart with such force. Obviously the weld let go as it was cooling.

 

[Specialist]

Hmm, interesting. What I would try first when welding such two pieces together would be to preheat them to at least 120, maybe 150°C, and also to cut a bevel edge in 40 mm bar, at least 40° over 5 mm. Preheating would take care of bad fusion with the base plate, and welding would be done with base plate vertical and bar horizontal, turning the parts around the bar longer axis as you pass each side of the bar, as to keep the welding always in horizontal position. That, together with preheating, and half-V bevel edge preparation, should ensure proper penetration into base plate. After welding, stress reducing at about 200 to 250°C for at least half an hour would be advisable. But that is only my idea based on limited info I have, and you will know better what to do as you have pieces at the hand.

Other possibility, if same happens again is, that base plate is not a compatible material. Did you buy that plate, or did a customer gave it to you for that job?

 

[KTMMICK]

Hmm, interesting. What I would try first when welding such two pieces together would be to preheat them to at least 120, maybe 150°C, and also to cut a bevel edge in 40 mm bar, at least 40° over 5 mm. Preheating would take care of bad fusion with the base plate, and welding would be done with base plate vertical and bar horizontal, turning the parts around the bar longer axis as you pass each side of the bar, as to keep the welding always in horizontal position. That, together with preheating, and half-V bevel edge preparation, should ensure proper penetration into base plate. After welding, stress reducing at about 200 to 250°C for at least half an hour would be advisable. But that is only my idea based on limited info I have, and you will know better what to do as you have pieces at the hand.

Other possibility, if same happens again is, that base plate is not a compatible material. Did you buy that plate, or did a customer gave it to you for that job?

First establish if it is Stainless.......a magnet will do that! Then simply use dis-similar rods............could be the different cooling rates have you any penetration on the base plate? if not maybe the current is set wrong....what size rods? how many runs maybe do three smaller runs. Always a chance when supplied material from a customer, they may just be looking for a cheap job.

 

[zzr1200]

The second one didnt break, but when belted with the hammer, that one too fell apart.

Parts were supplied to us ready for welding. Any ideas what the baseplates could have been cut from? They certainly look like stainless Seems strange that the first would blow apart with such force. Obviously the weld let go as it was cooling.

Ask customer to confirm material spec, it could be that they have used 'old stock' to reduce overall costs!!!

PS. Do you have one of those kits to test type of stainless it is???

 

[Tungsten Sharpener]

pre heat and post heat, the solid will act as a heat sink and rob the weld, cooling much faster than the plate.

TS

 

[Welderpaul]

All the stock was provided by the customer. When asked they had no idea what it was, where it came for, and didnt sound that interested. Odd seeing as it was a mega rush job last time they were on the phone.
Discussed a few options with them. Might as well be talking to the wall. He said, 'well just as long they come back to us stuck together'. What an ****.
So.. they are now installed. Baseplates drilled and counterbored, posts drilled and tapped - bolted together with M12 allen screws.
They are more than happy!
Still don't know what it was - it didnt drill like stainless, and wasnt magnetic. Very very fine swarf, almost like cast produces. Very small, almost non existent orange sparks when touched with the grinder.

 

[Drains]

Apart from the drilling, sounds like 316.

Did you preheat then Paul, or do a bengal on it?

 

[Welderpaul]

Yes, oddball material. Very strange.

No preheat

Do a Bengal?

 

[chunkolini]

A bengal?
Lancer? tiger? match?
I was expecting to see a post with piccies of super tidy 'crackin'' welds rather than a post about welds that crack.

'''well just as long they come back to us stuck together''

Obviously a quality customer who cares about his customers down the line.

Chunko'.

 

[Wozzaaah]

Bengal lancer - chancer

Glad it's sorted Paul, bet you can do without jobs (and customers) like that eh?

 

[Welderpaul]

Begal lancer - chancer

Glad it's sorted Paul, bet you can do without jobs (and customers) like that eh?

Yeah, jobs like that there's always a solution or a way round. The problem is more with the customer.

 

[Drains]

A bengal?
Lancer? tiger? match?

Bengal match Chunko'! Not many people know what those are!

Wozz put his finger on it, BTW.

 

[Wozzaaah]

Shame I didn't spell it right though

 

[Hitch]

Not some Inconel they bought you round was it?? Slightly whiter colour than the 316 square stainless?

Normally welded with special inconel fillers i think.

 

[snowcat]

My money would bo on Inconel as well a ****** for cracking that, mind inconel is a small fortune (and the consumables to weld it) so seams strange to let it go for mundane.....

 

[hotrodder]

303 free machining?