Welding Cast Iron

[Hoverquad]

I recently had a badly broken Ajax Saw in my workshop, it hadn't started out that way, but a little pressure in the wrong spot removed the rear blade boss from the main overhead arm. Leaving a useless
piece of kit. Now every man and his dog knows you have to clean and prep, then heat up in an oven else you will never weld cast iron for it will just crack up everywhere. Well, that's not strictly true, a friend of mine with stick welding gear followed a way of repair that I had heard of from the states. This involves cast iron rods of course, tack here and there to hold the sheared piece in place and then let it cool, tap the oxide off and leave. Return later and start a small stitch at every tack, less the half an inch, hit the slag off and don't be timmid. Leave and repeat the process until you have built up several compact runs all around the offending repair. My Ajax Saw is now as good as new, a little uglier perhaps, but going strong. It seems that the hits to remove the slag help to distress the metal and the fact that it does not really get that hot due to small stiches is the answer.

 

[Paul.]

Moved to the correct section,
Cold welding of cast iron is quite a common technique, and is generally to be preferred over preheating unless you have a means of properly controlling the heat input and cooling rate,
http://www.mig-welding.co.uk/welding-cast-iron.htm

 

[TechnicAl]

The hammering is called peening and its supposed to relieve stresses.

Unless you get Cast Iron very hot you will get better results "cold" welding it. Its a technique thats been used for years in the UK.

The filler metal is either pure Nickel or a Nickel Iron Alloy (55/45 or 60/40). The Nickel doesnt absorb Carbon from the CI and therefore stays soft and malleable.

Incidentally there are lots of different grades of Cast Iron, some are not weldable by any method.

 

[rtbcomp]

..........

Incidentally there are lots of different grades of Cast Iron, some are not weldable by any method.

A specialist welder I used told me this, and for this reason he refuses to weld cast iron.

 

[God mode restorations]

Welding cast iron can be done..there are lots of different grades..i weld a lot of cast pipe fittings on my dads tar tanker..i used a disimler rod..think I spelt that wrong...but never had any problems....just thought I would stick me pennies worth in

 

[Kent]

Now I never did a lot of it, just bits so I am no pro at it but the 80+ year old guy that owned the company I worked for did a lot of it for all sorts of people. Long preheat under an asbestos!!! blanket with propane and then cast welding rods (funny square ones) and Gas welding. Seriously we had an old milling machine and it was broken into two halves being delivered some place, he welded it together many years before I stepped into his place and yeah, it produced some tight tolerances!
Welding cast with stick was not allowed and I still think if its past peening and pinning or wont do with two pack epoxy its not worth putting an electrode near it. Shame I don't see those gas welding rods for cast if I could get some cheap enough I should like to experiment and learn more fully myself.
Shame people like that didn't almost force the lads to learn this stuff but I have to say he was a grumpy old blighter, his brother (the last of the old time blacksmiths) was a similar age and was a totally different kind of guy

 

[God mode restorations]

Old school techniques are awesome..and its a total shame that some are long gone and forgotten about...

 

[TechnicAl]

The square rods are still available. I think Weldability SIF still sell them.
The reason you dont see many these days is because they are not as good as the stick electrodes. They are essentially cast iron and as such don't have the ductility. They work because gas welding gets the casting very hot........best results over 700 oC. At lower temps they often crack.

Gas welding and TIG welding put too much heat into the casting. MMA and MIG are the best processes

Welding with Ni and NiFe has been performed successfully for donkeys years. I know it was used in the 60s and probably earlier.

 

[JDJones]

Hi Hoverquad
As a welding instructor in the 70s/80s cast iron welding was part of the course both Oxy/Acetylene welding and MA welding I remember cutting the 6 inch cast iron sections in half to save on pre-heating gas also using mild steel electrodes for filler because the nickel electrodes were so expensive, all motor vehicle students, YTS students welded cast iron, we would break up old cast iron inlet and exhausts to save money as well.
I Oxy /Acetylene welded carpenters planes Stanley and Record planes, for the carpenters shop when the boys dropped them onto a wood block floor, the cast iron in those was very high quality, much higher quality than in the car engine parts. All the Best Boys desmo11225

 

[Bill Edwards]

Welding cast iron with MMA using nickel rods is remarkably easy and simple. All you need to do is keep it cool enough to keep your hand on and peen it while it cools.
It's successful and my favorite is welding engine blocks/heads that people believe must be scrap because they're cracked...
Patience is all that's required.

 

[Tigman]

I think its a matter of Suck it and see , trial and error , sometimes it welds lovely with no pre heat , then the next time it just wont weld , ive done a fair bit and always get a result! if all else fails Brase it !

 

[Bill Edwards]

Preheat would be a little worse than awkward for an engine block still in the vehicle!

 

[norlander]

sometimes it welds lovely with no pre heat , then the next time it just wont weld

I think that reflects what somebody has already said-that there is CI and then there is summat that looks like CI, weighs like CI -but welds like MK 1 crapite-which is what it probably is

 

[TechnicAl]

The most common unweldable type is called White Iron and the most common weldable on is Grey Iron. The colour refers to the fractured face. Its possible to see the difference but you really need them side by side.......unless youve got years of experience

 

[captain-destructo]

a friend went to collect some powder coating today
a nice cast iron balcony

looked great apparently till he noticed a foot had been snapped off then when looking for the foot so it could be welded back on they found another piece that had been snapped off but couldnt find the foot

so he left the two damaged sections there to be repaired and took the rest to the job
when he got there he was looking at the newly rebuild brick pillers that are a different size to the original ones that were there when he measured the gaps for the new fence panels (collected this morning by the galvanising company) he just made to match the balcony

he not a happy chap

 

[Kent]

The square rods are still available. I think Weldability SIF still sell them.
The reason you dont see many these days is because they are not as good as the stick electrodes. They are essentially cast iron and as such don't have the ductility. They work because gas welding gets the casting very hot........best results over 700 oC. At lower temps they often crack.

Gas welding and TIG welding put too much heat into the casting. MMA and MIG are the best processes

Welding with Ni and NiFe has been performed successfully for donkeys years. I know it was used in the 60s and probably earlier.

Well we had all those ways available to us and he should have very much disagreed with MIG and Stick being better, how many of us have 70 years hands on experience and get this he learnt off his Dad!

 

[sardine]

I have successfully stick welded cast iron parts from solid fuel stoves with a preheat to 350 / 400 deg C and a pure nickel electrode, doing tacks all along the joint, and letting it settle, then repeating until the whole joint is filled, double vee' d mostly. Burying in sand for an over night cool down. I have a piece of cast done like that in my wood burning stove, its had a daily hot / cold cycling for over a year now.

 

[premmington]

Cast iron. Repairs with no pre-heating can be achieved using MMA with very expensive nickel/iron electrodes. Lincoln Electric Reptec Cast 3 2.5mm 50-70amps DC/AC negative polarity for electrode, positive for earth clamp, are the best we have found. Welding small runs of 30-50mm then allowing to cool before starting again

 

[TechnicAl]

Well we had all those ways available to us and he should have very much disagreed with MIG and Stick being better, how many of us have 70 years hands on experience and get this he learnt off his Dad!

and kids were up chimneys, ponies down the pit and rickets was rife...........

 

[TechnicAl]

Cast iron. Repairs with no pre-heating can be achieved using MMA with very expensive nickel/iron electrodes. Lincoln Electric Reptec Cast 3 2.5mm 50-70amps DC/AC negative polarity for electrode, positive for earth clamp, are the best we have found. Welding small runs of 30-50mm then allowing to cool before starting again

Good.......I developed those rods
They were the first Barium free.......they said it wasnt possible but we did it and now they are all Barium free (as far as I know)