toe cracks while welding 316L stainless

[chief-welder]

Pictured is a turbo adaptor from a Detroit Diesel engine. The material is 1/8" 316L stainless. We are experiencing toe cracks into the base metal. Could this be due to the high heat it is exposed to than trying to weld on it just puts it over the top? The individual who welded on it used 308 filler wire. Could this contribute to the failure?

[Mike Sherman]

Chief, there are several things you should consider when welding this turbo:
1) Why did it crack? My guess is the exhaust bracket is loose and allowing the pipe to put too much weight on the turbo. This must be fixed or the turbo will crack again.
2) You must grind out all of the crack before welding. Welding over a crack will never work. The crack will continue to propogate and come right through the new weld.
3) This is a high heat application, the 308 onto a 316L base metal is not the best. You need to match the base metal and keep things very clean. This should be readily weldable if you follow the rules.

[Guest]

Along with your dissimilar metal problem, It looks to me like it was welded too cold. 316L welds real nice...."when you follow the rules".

[Jerry]

I must agree with keeping with the same filler here and trying to get all of the crack out, I also like to at times drill a small hole at the ends of a crack yet still try to get most of crack out or hope penetration will reach depth not able to cut out.

Did this crack develop directly over top of previous crack, or is crack on the weld edge way away from original crack.

There is a rod I use in the repair of tool steels that I use only for cracked dies. I mean A-2,D-2 stamping dies that are cracked or busted in half. This rod is a shock resistant rod and welds beautiful to almost any material. Weldmolds 888 tig rod, I believe my partner used this once on a very large stainless block and worked good.

J P Streets Welding

[morpheus]

Originally posted by Rocky D
It looks to me like it was welded too cold.

I don't know anything about welding stainless but my first impression of looking at how the weld failed it looked like it was welded too cold like Rocky said.

- jack

[Mike Sherman]

The weld was probably too cold, but that is not the particular or only reason it failed. The most perfect weld will fail if you weld over a crack. You cannot "burn it out". You must remove the crack as stated, then address the issue of too cold.

[DEA]

When you say to grind the crack out.
Do you mean all the way through,or until you can't see the crack line anymore?
I think thats what I mean to ask
Doug

[Guest]

Yes, grind the crack untill you can no longer see it. however the crack could still be there. Dye check the area where the crack was to be sure it's gone. Dye Penetrant Method (DPM) is the best field test procedure to eliminate cracks.

[aircraft]

Re: toe cracks while welding 316L stainless

Originally posted by chief-welder
The individual who welded on it used 308 filler wire. Could this contribute to the failure?

duh,,, that 308 was a really bad choice. That weld also looks bad too.

[DEA]

Thanks
And should you always drill a small hole at each end of the crack if feasible?
What would the rejoining procedure be for a broken frame(in half) on a motorcycle or race car frame? Could you just tig them back together or should you use a collar of some sort?
I'm not going to do this yet,just preparing for later!
Thanks again