Any metallurgists in the house

[karstic]

Any idea what causes a weld to flake like this?



This is the collector on a Gibson stainless steel exhaust. The welds on the inside of the collector has completely "corrode" away

The large bright spot is in the middle of four of the tubes that come of the head and meet at the collector. It's about 1/4"-1/2" across. The weld has completely corroded awat. The smaller light spot is at two of the other tubes.



Anothe area of corroding weld



I hope Gibson will cover it under their warranty

 

[karstic]

The weld has completely corroded away



Corroded weld between exhaust tubes.

 

[FordGuy]

Maybe using welding wire with a high carbon content ?

 

[8Mud]

I've seen that before, never did figure out the exact cause, but my best guess was somebody substituted cheaper metals in the wire. Heat, electrolysis, oxidation or all of the above caused premature breakdown of the metals.
Non ferrous metals and ferrous metals swap electrons naturally, the process is accelerated with heat or certain blends.
Heat control during the weld can also be a problem, the lower melting point non ferrous metals can be overheated and turn to gas. Which can cause empty welds for lack of a better term.
Best guess is too hot of a weld and cheap materials.

 

[karstic]

Kudos to Gibson. They replaced the manifold under warranty. Glad I spent the money on the stainless.