Arc welding cast iron ?

[zardoz]

At least I think its cast iron. Its a very old fire (maybe 50 or more years old) from an old 'butty' tar barge. The fire has a crack down the back approx. 6 inches long. This is a piece of some of the same material below. It is approx. 3/16 thick. Will using cast iron rods and pre heating with propane be the way to go ?

I only have my STEL arc welder and a 185 Portamig, so I presumed the Arc would be favourite. But as ever, I'm sure some here might have a good or better idea how to go about it.

this piece is 3 x 4 inches

 

[TechnicAl]

theres a guide

 

[chevy2]

I occaisonally weld broken cast iron at work, broken gutters and downpipes on listed buildings etc where replacements arent available.

Obviously arc is the way to go with cast iron welding rods,
Normal clean workpiece and veeing out rules apply,
dont always have the benefit of preheating when working on a scaffold,
Normally do it with short runs of weld about 1/2-1" long,
Chip the slag and wire brush between runs,
not sure if this is 100% the correct method but i've had good success this way.

 

[nickk]

You should always pre-heat,i find nickel ferrite/nickel bronze work well,in my experience fireplace iron isn't the best quality & sometimes wont weld satisfactorily-suck it & see.

 

[sardine]

cast iron is pants

i repair cast iron stoves and ranges, mostly from narrow boats, i only use a pure nickel electrode, and put a gentle preheat on the whole peice, just too hot to hold is enough, the peice has to be on it's own, and not bolted or connected to anything else, it can't be restricted in any direction or it will just crack somewhere else, i put a fat full penetration "tack" every half inch along the vee'd out join, and cover it with my gloves, leave it for 10 mins, then i repeat the "tacks" overlapping them , and letting it cool, until the joint is filled.

I found the less weld heat you put in, the more chance of a good outcome.

I have heard standard MIG wire does the job, but iv'e never tried it.


Good luck.

 

[TechnicAl]

i repair cast iron stoves and ranges, mostly from narrow boats, i only use a pure nickel electrode, and put a gentle preheat on the whole peice, just too hot to hold is enough, the peice has to be on it's own, and not bolted or connected to anything else, it can't be restricted in any direction or it will just crack somewhere else, i put a fat full penetration "tack" every half inch along the vee'd out join, and cover it with my gloves, leave it for 10 mins, then i repeat the "tacks" overlapping them , and letting it cool, until the joint is filled.

I found the less weld heat you put in, the more chance of a good outcome.

I have heard standard MIG wire does the job, but iv'e never tried it.


Good luck.

Standard MIG wire wont work as well as the Nickel. It will be hard and brittle. Preheating isnt really necessary but "cool" welding is. Warming it like you describe wont do any harm and like you say reducing the restraint is important.

 

[Feet 'n Inches]

Probably teaching my grandmother to suck eggs, but I was taught to drill a small hole (around 1/8") at each end of the crack. Laying short runs and allowing time to cool is the way to go.

Good luck

 

[TechnicAl]

http://www.mig-welding.co.uk/welding-cast-iron.htm