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Up Topic Welding Industry / General Welding Discussion / Turbo Manifold
- - By Kix474 (*) Date 10-31-2002 07:05
Thin wall header tubing cracking on the outside of weld when wrapped with an espestos heat wrap. Don't know the grade od steel just know that it's mild steel tubing. What process would be best to keep this from happening and any post weld tips like annealing or something would be helpful also. Thanx Ray C.
Parent - - By pipewelder_1999 (****) Date 10-31-2002 14:25
If the heat wrap is on it while in the car and the tubing is carbon steel then it may be getting too hot.

Are the cracks happening after the car has been running or while fixing the headers.

G Austin

PS. I'm a complete idiot when it comes to cars so be gentle!
Parent - - By Kix474 (*) Date 10-31-2002 18:52
They are happening after the car has run for awhile. The cracks are in the heat effected zone and they probably were quenching the part right after welding. So do u think Annealing with solve this problem and maybe not quench the part after welding it? Ray C.
Parent - - By kam (**) Date 11-01-2002 15:21
Why are they quenching the parts after welding? Sounds like quench cracks to me. Kind of depends on the amount of carbon in the part. Generally you want them to cool a slow rate.

kam
Parent - By jwright650 (*****) Date 11-01-2002 15:49
I had a stock exhaust manifold crack on a 2.5 4 cyl. S-10. The manifold was made like a set of headers. It was made out of tubing. It had developed a crack around one of the tubes at the flange that bolts to the head. I took it off and welded it back up with a self shielded flux core .035" wire.
It has held through numerous heat cycles, but it did not have insulation wrap on it. I've sold the truck to someone I work with and He is still driving it. He hasn't mentioned whether or not its still OK, so I'm assuming it is.
Parent - - By billvanderhoof (****) Date 11-02-2002 06:06
Assuming that you run this thing pretty hard the tubing inside the wrap could easily reach 2000 deg F. Then you back off and it gets flooded with (basically) air at a few hundred degrees. Just the temperature cycling makes this a very demanding application. The chemistry of the gasses is probably no help either. I would think that any heat treatment done at welding time has been forgotten by the metal. I would fab a replacement out of some high temperature resisting material. I leave the recomendation of material to others who have experience in this area.
Bill
Parent - By jwright650 (*****) Date 11-06-2002 15:05
Could these cracks come from the exhaust not being supported well and the movement may be cracking it?
Just a thought,
John Wright
Up Topic Welding Industry / General Welding Discussion / Turbo Manifold

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