X-750 is also an Inconel alloy. Get in touch with the manufacturer, who knows his products better than anybody else and will be able to help you. The data:
International Nickel Inc.
Park 80 West Plaza Two
Saddle Brook, NJ 07663
Phone (1) 201-368-4800
Fax (1) 201-368-4858
Site: www.inco.com
If you're not from the USA, on the site you'll find who's INCO's representative in your country.
Giovanni S. Crisi
Sao Paulo - Brazil
Inconel 82 (ERNiCr-3) will work just fine.
Isn't X-750 the precipitation strengthened alloy? Can you weld it without growing the precipitate size in the heat affected zone and having reduced yield strength? I've never heard of anyone welding X-750, but that doesn't mean it isn't being done. It would be advisable to contact INCO Alloys techical support before welding.
Marty
Yes it is a PPtn strengthened alloy, and yes you will loose strenth in the HAZ, but the welded joint strength will still exceed the strength of the Inconel 600.