Welding 1900's Cast Iron to Steel

[RareBugTX]

Anybody done this before? I am doing a storefront rehab where there are 2 nice 1900's archiectural cast iron columns. Span is very small. We are casting new conc footings with plate. Any important considerations welding a-36 steel to the old cast iron?

Thanks

 

[youngstructural]

You are getting into a very dangerous area; This would definately require a specialist in weld engineering to write a specific welding procedure, assuming the iron is weldable (which it could easily not be!). This is well beyond your typical HAZ and embrittlement problem common with older steels... be VERY careful and seek specialist advice.

Is it not at all possible to use a bolted plate connection?

YS

B.Eng (Carleton)
Working in New Zealand, thinking of my snow covered home...

 

[youngstructural]

Okay, so I've done a little digging in some reference texts (including what I think is the most useful reference I have for your case - Handbook of Structural Steel Connections by Akbar R. Tamboli). Looks like your job is difficult by not impossible.

You need to do some testing to determine what kind of casting you have...

1. White iron is generally considered to be unweldable; Tamboli advocates looking at alternative connections if this is found.

2. Preheating is almost always required when welding cast iron (refer to my previous post re HAZ).

3. Any welding process may be attempted, however the electrode used should be a cast-iron electrode as specified in AWS A5.15.

4. The weldment must be permitted to cool slowly. (Did I mention HAZ?). Since you're dealing with a structural load bearing member (even though the loads are presumably small), you need to be concerned about embrittlement and brittle fracture.

Tamboli advocates testing the welding procedure before use, and lastly recommends the same things I do: A welding expert should be consulted.

Good luck!

YS

B.Eng (Carleton)
Working in New Zealand, thinking of my snow covered home...

 

[Vinny7]

As an alternative would it be possible to provide a circular hollow section small enough to run through the centre of the cast iron post. This would then be used as the structural member with connections made to this. The cast iron post around would just be for aesthetics.

 

[RareBugTX]

That's one of the possibilities. Great idea Vinny,

Thanks,

 

[DRC1]

Be careful drilling or taping to the cast iron post. The outside is a protective patina. any area exposed by disturbing the patina can cause corrosion of the effected area.