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.

 

[Ron]

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?

 

[ishvaaag]

http://books.google.es/books?id=Opf...zvWmBQ&sa=X&oi=book_result&ct=result&resnum=3

http://cr4.globalspec.com/thread/39647

 

[Lion06]

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.

 

[slickdeals]

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

 

[Ron]

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.

 

[Lion06]

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.

 

[JedClampett]

I'd use stainless plates and stainless studs and save your worry:

http://www.nelsonstud.com/Portal/Portals/0/pdf/Catalog/StudWeld/ConcreteAnchors/H4L.pdf

Note that you can get these in 316 stainless.

 

[Lion06]

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

 

[hokie66]

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

 

[Lion06]

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.

 

[hokie66]

What shape/size is the column?

 

[Lion06]

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

 

[hokie66]

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

 

[Lion06]

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.

 

[hokie66]

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.

 

[Tomfh]

What is the bending moment at the baseplate?

 

[Ron]

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.

 

[Lion06]

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.

 

[Ron]

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.