Landracing Forum
Tech Information => Technical Discussion => Topic started by: tauruck on August 26, 2015, 08:58:42 AM
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Got a great friend whose kid is into turbos.
They need help welding a mild steel flange to a stock Opel cast iron exhaust manifold.
Guess who "landed" the job????.
Without all the boring detail the solution locally is a special stick welding rod that needs the flux removed
in order to use it as a tig filler item.
I know you guys have the answers. If this deal goes south I'll be blamed for sure even though it's a freebie.
I couldn't find a pure nickel rod in my area which was the original suggestion.
Fire away. I'm all ears. :-D :-D :-D :-D
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Mike i used to play around with that sort of thing in the 80's
some manifolds like Chrysler and Ford welded easy but our local GM stuff would not
at the time we were welding steel flanges on intakes for 4 barrel conversions and exhaust for turbo
stick with low hydrogen rods worked well with very little cracking , depending how much carbon had permiated the cast (GM's problem)
mig worked pretty good later
got a spare manifold to practice with ? some reacted better to pre heat and others were better hitting them at room temp but short welds keeping temp out of the material
you may be better off fabricating steel or stainless , cast thick wall bends work great
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Your exhaust manifold is probably grey cast iron. I have seen this stick welded improperly and then immediately fracture as the joint cools. This is likely because the elevated temperature and fast cooling precipitates out the carbon and makes the heat affected zone very brittle.
Three proven possibilities to joining cast iron to itself or anything else is to preheat it so the weld cools slowly and the carbon does not stay separated. Also some cast iron welding rods are very soft so the filler material flexes instead of the base material so cracking of the cast iron after welding can be avoided. Another option is to braze instead of weld since that process can be much cooler than ark welding so the preheat does not need to be as high to accomplish slow cooling. These options may be all combined.
The manufactures of welding equipment, like Lincoln, and the manufactures of welding/brazing rod, like ESAB, suggest particular processes based on the type of cast iron. BOC gases also has helpful information. These manufacturers' suggestions likely come from their metallurgists. Go to these types of manufactures' sites and read about cast iron repair or exhaust manifold repair. Also a little reading can help you verify which type of cast iron your manifold is, based on its color or how the fracture line looks.
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Braising doesnt last very long on turbo manifolds, unfortunate as it would be a sound way to join the different metals
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Thanks guys. All sound advice. I'll only see the job on Saturday and let you all see pics etc.
There was a roll of mig wire to do the job but it was 12 grand. :evil: :evil: :evil: :evil:
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I'm not sure of the joint design or the grade of cast iron you're working with, so any suggestions would be subject to the alloy of the part your working with, any thing else would just be guessing.
In most cases I've seem, cast iron welding will not to stand up to thermal cycling, as in the case of a turbo flange, the best solution is to machine a mating part for the dissimilar metals and fasten together by bolting.
There are ways to weld parts like this, but you'd be well advised to have the particulars of both materials, and what each one needs as far as welding, before jumping into a welding project. Every cast iron takes different welding techniques and filler wire, just depends on what cast iron alloy you are dealing with.
Rouse
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In Vern Tardel's new Flathead book they used; Tig'd Everdure 656 silicone-bronze or Gas torch and Welco 17FC nickle silver alloy rod on Cast iron Flathead block. From page 116
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In Vern Tardel's new Flathead book they used; Tig'd Everdure 656 silicone-bronze or Gas torch and Welco 17FC nickle silver alloy rod on Cast iron Flathead block. From page 116
That's cool, so what was the cast iron alloy of the Flathead block??
656 silicone-bronze and/or Welco 17FC nickle silver alloy rod may work just fine on their Flathead block, and not at all on a different cast iron alloy.
The point I was trying to make, and it applies in particular to cast irons, is that not all cast irons are created equal, not even close in most cases, so knowing what your welding and the compatibility of the filler wire you use, will make a big difference in the outcome.
Full dis-closer, I don't have much use for welding cast iron and avoid doing so wherever and whenever possible.
Rouse
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Guys, the kid is the son of a guy I've known for 28 years.
He's got this little Opel FWD with a cast iron turbo manifold
built by someone else.
The flange is steel and whoever built
it seemed to have done a good job on the weld because it hasn't fallen off.
I think the bolt holes on the flange were an afterthought because they hadn't been
drilled on a press.
I drilled the new flange and countersunk the holes for some M10 bolts. The CS bolts were
2mm below the flat surface when installed so I tig welded the heads and the joined the new flange to the manifold
using steel filler rod. The turbo is 10mm further away from the original position.
Then there was this 90* elbow that needed to be welded to the cast iron. I used the hole saw to punch the hole
where he wanted it, cleaned the areas with the dremel and we used some special stick welding rods that we knocked the flux off.
The kid cleaned them really well and the welding went well. I was expecting the stuff to spit and spark but never had any problems.
This was cast iron to cast iron. Then there was a pipe for the BOV that was hollow bar, not cast iron that went on to the other end of the elbow. We used another stick welding rod made for cast to mild steel and that job also went well.
I don't know how this stuff is supposed to work but the guy's as happy as a pig in Palestine and the report is that nothing has cracked or fallen off yet.
I guess only time will tell. If it works as good as lit looks then I'm off the hook. Pics later.
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Mike;
I'll bet that rod was a high nickel alloy.
Regards, Neil Tucson, AZ
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Sounds like you have it going your way on that project. The only thing that has me confused is, what is all that "MM" stuff mean?
Rouse
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thought I'd get some loose parts in a box but instead I got a whole car
that needed Bov stuff and all the other components welded to V band flanges.
I worked most of Saturday and today. The little Opel left in a big "hurry"!!!!. :-D
It disappeared to be blunt. The kid rode it hard all the way home and the call came that
nothing has cracked or fallen off. Probably 16 welds with only two being the cast iron.
I never took too many pics because the FWD stuff isn't my thing.
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I think in this case rather large welds likely help the situation. I think it's fairly important that the whole area gets well heat soaked, otherwise the mass of metal surrounding the weld tends to chill things quickly and the weld is brittle. I think probably you were given what is commonly known as NiRod which is a high nickel rod designed for arc welding cast iron.
Anyway, glad to hear it was successful. Let us know if you hear of any breakage in the future. Otherwise I may try something similar the next suitable cast iron job I have. Sometimes you can teach an old dog new tricks. :-o :-o :-D
Pete
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Thanks Pete.
I got the advice from a lady at a welding supply company.
She suggested the rods. We had two, one for the cast to cast and another for cast to mild or other steels.
I'll check the nos later and post pics.
With my limited experience the material (cast) spits and makes lousy noises like when you forget to switch on the gas.
This time it was actually a nice job to do and took your advice. I never rushed it and it was so cool to get a good result.
I think the Opel manifold and the new gas supply had more to do with my success than skill.
Just thinking, you get cast iron and then you get the other cast iron. :-D
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Rouse, "MM" means Mickey Mouse here in Oregon.
That looks lie a good cast iron welding job. Better than any of mine.
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Rouse, "MM" means Mickey Mouse here in Oregon.
That looks lie a good cast iron welding job. Better than any of mine.
It could mean Mad Mike, Messy Mike or something worse but I think I might have been referring to Millimeters. :-D
Only time will tell if that weld is any good. I won't lie if it fails I promise!!!. :cheers:
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309 stainless filler also works well for this. I use it all the time welding on turbine housings (adding v-band clamps).
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Thanks Rob, I'll keep that in mind. :cheers:
I haven't heard from the kid so that tells me the weld is OK. :-D
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My Pop who was an ace welder always said regarding cast materials, "when in doubt grind it out" meaning root passes would get partially ground out and peened, next pass, the same and always peening the heck out of it. I never had a failure following his advice.
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Thanks John. I hope I never have to repeat the job.
If the thing is still together let's just say I got lucky. :-D