Welding carbon steel to stainless 1

[Lion06]

Does anyone have any experience with this? I've tried to look online (I even contacted Lincoln Electric), but have come up empty as far as design criteria and any potential issues that could arise from welding these dissimilar metals.

 

[JStephen]

As to the cost of weld qualification, you might check with the ones doing the welding to see if they already have a procedure for that.

Seems like I've seen either a 308 or 309 electrode used for cs to ss- I forget which is which- but it's been done.

 

[dig1]

StructuralEIT,

If you have to go with a stainless steel/carbon steel joint I would recommend using 316L instead of 304L due to the salt water atmosphere exposure (I am not talking about immersion but splash, spray, and in the air salt water). See the attached link

http://www.smacna.org/newsletters/index.cfm?fuseaction=view_article&id=1022

What is stated in here confirms what my experience has been in terms of 304L v. 316L.

As Ron stated earlier, make sure you use an L grade.

The electrode should be 309MoL with the 316L and 309L if 304L is used.

Make sure that there is no galvanizing in the area to be welded (I would leave 2" clear). The zinc from the galvanizing can react with the stainless and cause cracking. If the entire column has been HDG and you are grinding away the bottom 2" I believe there are some tests to make sure that all the zinc is out of the metal. I would recommend PT examinination of the weld.

I have worked on several projects where stainless is welded to carbon steel in a variety of applications (structural and pressure vessel) and if done properly there are generally no issues. Qualifying the weld procedure should not be an issue, other than the cost of the qualification which should not that expensive. I will find out how much it costs for an ASME Section IX qualification and that should be close to what you would need to spend.

Remember that 304L and 316L has a significantly lower yield (25 ksi) than A992 Gr. 50. Dual spec 316/316L has a yield of 30 ksi. If this is a problem, I would recommend 2205 duplex (A240-UNS S32205) with a yield strength of 65 ksi. The filler metal does not change (309MoL). The welding procedure and qualification is slightly more involved; however, there is plenty of literature to help anyone develop the propoer procedure.

This really is not a big deal and should not be expensive to qualify a weld procedure. However, I do not know if it is the best solution as many others have pointed out.

Patrick