I work with some of the very good welders we have @ my work and asked them the same thing when I cam across a stainless header that we have with rust on one of the welds. He said the same as above, that if a different filler/wire/stick was used it could cause corrosion due to the dissimilarity of the two metals. Also, he said that if the metal was heated excessively while the welding was occurring the result would be a weakened ability for the metal to attain its natural layer of oxidization which helps protect it. Rust is just a reaction of the metal in question
(iron, and specifically ironII if i remember correctly from chem class) with oxygen, the stainless oxidizes (but usually forms a different type of oxidation due to its low iron content) to a certain point but usually once this is reached the oxidation ceases. Hope this helps, I have a very shallow understanding of why this occures, so please don't flame me too much.

As for ComputerLJT - It took long enough. No love lost for an ignorant, prepubescent, passive agressive.

I apologize for going off topic in your thread Andy.

 

Damn can we stick to the post, gosh honda-tech drama for nothing. I was jus curious and wanted to know a lil more about stainless.

Yes, I am picky with my car, but I spend a lot of time and money on it. So ofcourse I am. I am not going to do anything about it, you can't even notice it. I was just curious why it happened because I thought stainless was rust proof. Figured you guys could educate me a lil more on welding and the material.

I was just told the place I got it coated at, burnt to the ground. So I will just live with it, or have my friend recoat it for me if I ever get some time to pull the manifold off. Like I said you can't tell and my car is running really well. I am a lil to lazy to be taking off that manifold right now.

 

is it the welds rusting?

 

is it rusting on the tubing or the weld?