Welding 3/4 inch 410SST to .250 A36 Carbon Steel

By Kix

Date 05-20-2008 15:33

What is the process to be used for welding? What is being built? Shielding gas depends on the process or mode of transfer to be used. I would still use a ER309L stainless rod, wire, flux core wire, metal core wire. Stress relief is up to the engineer.

By js55

Date 05-20-2008 18:55

I think your biggest problem is heat treat. It depends upon your code though. B31.3 stress relief min is 1350F (though there are recommended allowable ranges lower than this-often to 1200(AWS Welding Handbook)).
1350 violates transformation temp for carbon steel. You would have to use a transition piece if you can't reduce the temp. If no transition be aware of para 331.2.2 if working to B31.3.
Also be aware of the hardness requirements. This is your friend.

By js55

Date 05-20-2008 19:03

Oh, I also think Kix's recommendation for 309 is good. Thermal expansion similar to 410 relieving stresses on a very brittle HAZ. Good H cracking assistance and good compatibility with C-steel. Keep in mind too that Mf temp (martensitic finish) is ~480F so even though some recommendations say 500 or so preheat, it may be beneficial for you to stay under 480 to allow as much martensite to transform as possible so your multipass weld on that thick of material can temper prior passes.