4320 to A36

Date 01-15-2009 18:13

A lot of this depends on the Fabrication Code you are using. Your welding procedure (WPS) should provide you with all necessary info to make a weld between the two materials, that is if you have a WPS. General comments are as follows:
(1) When welding two materials with quite different mechanical properties, you would normally use filler materials that match the lower strength material of the two (in this case the A36). That would suggest E7018 (SMAW), E70S-2 or -6 (GMAW), E70T-1 (FCAW), etc.
(2) Preheat would be best to match the requirements for the AISI 4320 due to the potential for HAZ hardening. Something in the range of 300-450F would probably be necessary, with maximum interpass in the range of 500-600F. This again would depend on the end use and if HAZ hardness control is necessary. Base metal thickness would also be a consideration.

If more info on the end use of the weldment is available, more applicable advice can be given. The weldability of the two materials should not be a big deal. You probably won't see any difference between the two, from any other common mild steel.

By ctacker (****)

Date 01-15-2009 18:23

Thanks fred, we are getting ready to make a procedure under ASME, will be welding 4320 manifolds to A36 flanges. I was thinking along the lines of E70C wire using Pulse. I am preparing to make a WPS, thats my reasoning behind the question. I would guess the base metals would be no thicker than 1/2", possible a bit more for the flanges.