Cast Iron Welding

[Snowgoose-1]

After shot blasting, can extra iron be added to a keel ?

A friend of mine has some wastage but probably too big for filler. One hears of say barges having a new bottom. Do they just weld to good bits if they are good enough ?
TIA

 

[PCUK]

Cast iron needs heating before and during welding and would therefore not be suitable for building up the keel while still attached to the boat.

 

[Davy_S]

I have stick welded a cast iron log burner, but only because i was able to heat up the surrounding area with a blowlamp, but as said above by PCUK you won't manage to do a keel, we attempted to weld a pole to a large cast iron mooring bollard, it was impossible.

 

[KevinV]

I have successfully mig welded cast iron, but had some disasters too. Don't even think about it on a keel, the metal (even after blasting) will be horribly polluted.

 

[Bouba]

We have all successfully welded cast iron garden ornaments....but would not do it on a major safety item

 

[Alicatt]

My father could forge weld cast iron, he did it with an exhaust manifold for a 2.3 Vauxhall Victor which had cracked and broken off, none of the welders or blacksmiths in the area would touch it, was still going strong 3 years later when we sold the car.

 

[Wansworth]

The local agricultural engineer made a good fist of wielding up a broken hinge on cast iron stove using special rods

 

[Boater Sam]

I have stick welded up a freeze split across a gas boiler cast iron central heating heat exchanger. Vee'd it out first with a burr. used proper cast iron rods, slowly, no preheating.
Still OK as far as I know

 

[vyv_cox]

After shot blasting, can extra iron be added to a keel ?

A friend of mine has some wastage but probably too big for filler. One hears of say barges having a new bottom. Do they just weld to good bits if they are good enough ?
TIA

Relatively recent barges are built from sheet steel, easily welded. Older ones (100 years?) could be wrought iron that would typically be riveted, e.g. as Titanic was. I am not sure if this could be welded but maybe using similar materials as used for cast iron.

Cast iron has a high carbon content, needing special rods. The flux coating is designed to absorb as much carbon as possible. The electrodes are nickel, or nickel + steel for welding iron to steel. The latter might be a possibility for your requirements, adding a steel plate at the base of an iron keel could work but we would need to see the exact problem.

 

[Bouba]

Getting the right welding rods is easy, they sell them at my local DIY shop....but welding cast iron can lead to micro cracks and that can lead to future weakness...ok for that ornamental windmill in your garden...not so for a keel mid Atlantic

 

[rotrax]

I have - had - the reputation for tricky welding jobs "Take it to that bloke in the Motorbike shop-'ee can weld shit to perspex!"

I once got the job of re attaching 157 fins to a pair of 1919 Precision-the make of engine-vee twin cylinder/head units. My mechanic and I did four fins every day, first thing after lunch. The cylinder to be worked on was put on our 4KW electric Industrial Hotplate to pre heat, the four fins were affixed and it was then returned to the hotplate to cool down slowly, avoiding thermal shock.

It took five months...................................

Cast Iron welding is a 'Black Art' not a science. Cast Iron, especially malleable or spherical graphite cast iron, can be brazed, but careful preheating and delicate temperature control are needed.

You wont find much of that in a Boatyard........................................