I suggest that you get in touch with the manufacturers of Inconel alloys and ask them. They're very kind people and will be glad to help you, moreover taking into account that you're asking a question on how to use their products.
Their site: www.inco.com
The former International Nickel Company has been bought by the Brazilian Vale, so don't be surprised that when entering the site it says Vale.
Giovanni S. Crisi
Sao Paulo - Brazil

Hi Rangerod!

Here's a .pdf document you may find interesting since it's published by Special metals who currently produce many types of "Inconel" and it's associated alloys... I recommend you scroll down to page 26 in the .pdf to look for "Dissimilar Metals" and read on:

http://www.specialmetalswelding.com/publica/joining.pdf

In this .pdf, scroll down to page 24 where it begins to cover dissimilar welding:

http://www.specialmetalswelding.com/publica/welding1.pdf

Here's another interesting article from the Nickel Development Institute:

http://www.nickelinstitute.org/index.cfm/ci_id/3286/la_id/1/document/1/re_id/0

This is the name of the company now which makes "Inconel" and it's wide, diverse family of alloys used in just as many different applications and this is their contact info page:

http://www.specialmetals.com/contact.php

Here is a page loaded with links to all of Special Metals different companies and divisions worldwide:

http://www.specialmetals.com/companies.php

Finally, here is Special Metals Welding products Company website:

http://www.specialmetalswelding.com/

This is their Global contacts links for all of their Welding products:

http://www.specialmetalswelding.com/contacts/contacts/contacts.htm

You may also want to check out this forum these folks have:

http://www.specialmetalswelding.com/contacts/weldfrm.htm

Now you'll probably read from some other folks that a 309 filler can be used instead, but unless we know specifically what your application is and the intended service conditions, none of us can give you a "silver bullet" type answer which will refer you to one specific filler metal for your application... So go ahead and contact these folks and they'll help you sort out all of the particulars for your specific application and give you very sound advice. ;) I hope these links are helpful to both you and anyone else that could use them. ;)

Respectfully,
Henry

What process are you using to weld it TIG, stick, MIG or?
When I have TIG weld Inconel to SS it was 316 or 308 and I used 316 ELC rod.
I hope that helps.

Sincerely,
Kent