porosity in stainless to carbon

by john
(georgia)

i'm tig welding standard carbon to 304 stainless pipe with 309 filler rod why is there porosity?

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here are some things to consider:

is the metal clean?

are the cup size and flow rate of argon right? too small a cup size along with too much flow will cause porosity

is your electrode extension right? too much extension will cause loss of shielding and porosity