wierd color on 304ss sch40?

by DanieL
(Phoenix,AZ)

Hi How are you,

Im fairly new to tig, ive been crafting turbo manifolds, im getting great color and beads on my runners back gassed and all with 308 rod! but when i get to welding the runners to the collector where they all meet im getting a dark color as if its too much heat no matter what i do but no porous areas from lack of gas ? any ideas? thanks
-Dan

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Dan,

I am guessing that area is a little thinner and stays hot longer. Thats usually the issue.

using a bigger cup, a little less heat, and stopping often to let cool might all help