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Welding carbon steel to stainless

Welding carbon steel to stainless

Welding carbon steel to stainless

(OP)
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.

RE: Welding carbon steel to stainless

It depends on the type of stainless steel.  It can be done successfully, but you have to be careful about the electrode choice.

What type of stainless steel, what grade of carbon steel, and what is the application?

RE: Welding carbon steel to stainless

(OP)
It's most likely going to be 304 stainless and A992 carbon steel.  The stainless will be an embed plate in a 10" thick slab.  The A992 will be a column that gets field welded to it.  The reason for the stainless embed plate is that it's a beach house so the environment isn't good for carbon steel.  The reason I need an embed plate and can't use a typical baseplate detail is because the architect doesn't want to see any anchor rods or nuts above the floor line.  I wanted to use a typical detail with the baseplate and the bottom foot or so of the column HDG, but the architect wasn't having it.  This also means that I need to make the embed plates considerably oversized, because they will (without fail) misplace several of them.

RE: Welding carbon steel to stainless

Can you not recess the slab and use a typical base plate and come back and cover it up after the column is set?

RE: Welding carbon steel to stainless

You might want to specify it as 304L plate. I don't know the specific electrode, but likely an E8018 or similar, low hydrogen electrode.  Since you'll have to qualify a welding procedure specification for this anyway, get the electrode supplier to suggest an appropriate electrode.

I have welded stainless steel to carbon steel using common electrodes (E6011 and E7018), but it was for maintenance stuff, not building structural under code.  Worked fine, but wouldn't have complied with AWS for structural welding code.

RE: Welding carbon steel to stainless

(OP)
slickdeals-
I didn't consider that.  I am only dealing with a 10" slab, though, so I don't want to cut into it too much.  I'll see if I can get enough embedment doing that.


Ron-
Thanks for the input.  That's good to know that a welding procedure will need to be qualified - I didn't realize that.

RE: Welding carbon steel to stainless

(OP)
Jed-
I'm welding an A992 column to the embed plate.

RE: Welding carbon steel to stainless

Silly idea, silly architect.  The whole thing should be galvanized.

RE: Welding carbon steel to stainless

(OP)
I agree the whole thing should be galvanized, but what's a guy to do when the arch doesn't want to see anything above the floor line and it's all exposed to view?
I considered galvanizing in the field, but it won't be HD and it doesn't provide as much corrosion resistance.

RE: Welding carbon steel to stainless

What shape/size is the column?

RE: Welding carbon steel to stainless

(OP)
Right now the columns are W12x96 (drift is controlling the design).   

RE: Welding carbon steel to stainless

If they are already that large, why not use reinforced concrete columns?

RE: Welding carbon steel to stainless

(OP)
The roof beams need to be steel (there is limited depth and they have some pretty aggressive cantilevers), so I thought it smart to continue steel througout - maybe not, though.
I would have to check concrete for drift (I think the sizes would need to go up for concrete because of drift and the long-term sway from the roof cantilevers).


Does anyone know how expensive it is to qualify a welding procedure?  If I can't get it to work out using slickdeals idea, I'm considering having a 1' stub column (with the embed plate) HDG and cast in - leaving the top 4"-5" of the column stub ungalvanized.  Then when the column sticks get there provide a full pen weld and have them grind it smooth.  I know that would be expensive, but I don't know what it costs to qualify a welding procedure.  Another serious problem is that I know they'll never get the plates/column stubs located correctly and then what kind of fix could I do?  I guess that idea's out.

RE: Welding carbon steel to stainless

I doubt that the stainless plate gives you a better solution corrosionwise.  You still have the rest of the column.  I would spend the money on the coating system.

With only a 10" slab, you won't get a lot of fixity of a 12" column base.  I assume your header beam will be moment connected to make a rigid frame.

RE: Welding carbon steel to stainless

What is the bending moment at the baseplate?

RE: Welding carbon steel to stainless

SEIT...I would shy away from the full pen weld in the field.  Unless you have NDT done on the weld, you won't know what you have.  If you have NDT done on the weld, you'll have a tough time getting it to pass.

You could still galvanize everything and just have the column-to-baseplate weld in the field....you could then coat the hell out of that weld and probably be fine with it.  Corrosion wouldn't be any worse than with your SS/CS weld and you wouldn't need to qualify a procedure as long at the galvanizing was ground off before welding.

Any thought to using a deeper footing, using blockouts for the slab and center of the footing and embedding the column to achieve fixity...no bolts, just embedment?  We do it with aluminum columns routinely.

 

RE: Welding carbon steel to stainless

(OP)
Ron-

What kind of coating would you suggest?  I thought about some kind of paint system - some of the epoxy coatings are pretty good for corrosion resistance, but I have to look into it a little more.

RE: Welding carbon steel to stainless

SEIT..Yes, epoxies are good for this.  Make sure the surface is prepared in accordance with the manufacturer's instructions.  You could even consider an epoxy casting to a point above the weld.  

RE: Welding carbon steel to stainless

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.

RE: Welding carbon steel to stainless

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
 

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