Thread: How do I weld Cast???

Hi

As an apprentice, I learned how to weld cast iron. The method then was to use an oxy/acet torch with a cast iron filler rod. It was important to provide overall heat to the item being welded to help reduce stresses within the item and weld.

I recently had the need to weld a small cast iron part and seached in vain to find cast iron filler rods. The best I was offered were "cast iron" arc welding rods!

These turned out to be what seems to be flux coated "brazing rods". In effect I ended up with a brazed part, but done via the arc welder.

I was initially surprised at the result, not expecting to see the brazed finish, however the part was welded and it turned out to be a very strong repair.

I did not question the supplier about the rod's material, so I am guessing at the "brazing rod" material. I would think though, that such a rod would effectively allow you to "braze" the dissimilar materials (ci/ms) to each other by the use of your arc wleder.


HTH
.

Woodlee, what the hell is that thing?

Originally Posted by Grahame Collins

g_man,
Ok! If you have to stick weld!

• Preheat the cast to cherry red -or if its a large piece as hot as you can get,

grahame He has no oxy , so no pre heat

Originally Posted by Grahame Collins

Hi Guys,
Cast iron is something you don't weld unless you really ,really need to.
Welding cast iron to itself presents enough problems but welding it to something else,well it just gets more difficult.It not a job for a novice welder.

I have done cast to cast repairs and cast to mild steel and even with cast iron rods ( which only gave a resonable result cast to cast ) i found brazing the best method , I use to use a bronze tinning flux as I found this worked better than a brazing flux
I realize you have no oxy so I would suggest you go with the bolt option ,

You can heat it with a large propane torch (no oxy).

Dad welded a vise jaw back on that had broken, including screw and thread. The first MIG weld cracked off. The second run held as so much heat was in it by that point. Not really a weld you can trust, but being on a vise jaw, the weld is only in compression, not tension. It hasn't broken after 5 years or so either.
But yeah, much better if you preheat it.

If you can somehow or somewhere obtain some Magna 770 electrodes you might be surprised how easy it is to weld CI , even without preheating. I know this flies in the face of most peoples experience, but using these electrodes is the closest thing to magic I have experienced as far as welding CI is concerned. Google is your friend.

Regards.

Grahame,

LOL ,,, I wasn't suggesting he rush out and buy one , too damn expensive for the average home workshop.
I bought this to do one job ,the guy I was doing the job for paid for half of the torch set up and I only charged labour for the job .It saved him a lot of time and expense on an A Model Ford restoration.

I had an old CIG torch that was made when the ark was built ,Eutectic at the time was taking trade-ins on old torches .So I bit the bullet and bought it.
I signed up on a course with Eutectic to get the benefit of their know how ( and scrounge some free powders ).So far I have never had a failed weld with this torch.

I have done quite a few jobs with it and it has paid for it self ,not so much in dollars but by saving machinery and and some antiques from going to the tip.
I have welded an engine cylinder from a 1948 Harley Davidson (WLA?) , repaired an engine block crack in a A model Ford engine (plus a heap of other parts), welded a lot of old cast iron stove parts and repaired a broken Disston saw filing vice. A stack of cast exhaust manifolds from different vehicles.
I also used it to do some repairs on my 1960's vintage Parkanson power hacksaw .

The next job for this is a Stanley 5 1/2 that has a crack down one side ,if it doesn't work it will cost only time some powder and gas.
I have already repaired a Stanley 78 rebate plane that belonged to my Dad ,(he dropped it and broke it in half ).I wouldn't have bothered but it belonged to my Dad, that's what sons are for,,, yeah ?

The Harley and the Ford are still going BTW .

Eutectic have some excellent technology , but you pay for it .
They make excellent welding rods too ,for cast iron and tool steels ,one that comes to mind is the Eutectic 680.

Kev

Originally Posted by g_man

Woodlee, what the hell is that thing?

Gman ,
Its a Eutalloy Super Jet 2000 gas torch ,It uses very fine metal powder to weld metals together .
It works like nothing else on cast iron .
Basically the metal powder comes through the torch tip with the flame and bonds with the parent metal , you use it like filler welding but no filler rod.

It can also be used to apply hard facing to tools and cutting edges amongst other applications.There are a variety of different powders available for different applications.
Kev.

[

If you can't be swayed from stick welding, use a pure nickel rod as first choice, a stainless steel 316L electrode as next choice and finally a low hydrogen electrode as the cheapest ,but nastiest choice .I think what will ultimately dictate your choice is the cost of the electrode,be sitting down when you get the price!

However, if you can be convinced not to stick weld ,pally up with someone who has an oxy set and braze the job - best option of the lot.

Does that help?

Grahame[/quote]
I am on 100% on Graham side as l have done it many time for farm and industrial work and is no big deal if you know what sort of cast iron is ???

what you can do is build a fire outside then place the item to be welded in the oven {when your wife is out} on high leave there for about an hour then wearing gloves remove from oven take outside having previously ground aweld prepon either side of the parts to be welded you can then use stainless electrodes as they are high nickel you will get some weld dilusion but it works when it is welded place in the fire cover with the hot coals and leave to cool naturally did this as an apprentice over 30 year ago

We were taught to peen the welds with a chipping hammer (a real and hardened one) as the welds started to cool. This helped to ease the shrinkage. For the most part this worked quite well. Preheating in the oven is a good idea as well. So is waiting till the missus is scarce.

I Broke a cast iron mortising attachment. ( tightened it a bit to much).

I repaired it using what ever arc rods I had using the cheapest arc (cig) welder. No preheating. I am not a good welder.

Used a grinder to make the job neater.

No problems. I am still using it.

I you have a choice of tossing something in the bin or trying to fix it , why not try? You have nothing to loose.

(now that stanley No 2 repair was not as successfull)

With reference to to the cast iron iron repair with standard rods,my comment is that you were extremely fortunate to be successful.

You just cannot make a blanket statement and say 'Because I have done and succeed you should be able to as well.'

There are variables being ignored here.

HERE ARE SOME VARIABLES

• Cast iron metallurgy can contain up to 100 times or more carbon content than the steel make up up of the welding electrode,
  
• The behaviours of the two quite different molten metals as they cool are different from one to the other.
  
• Iron that cools slowly can distribute stress contained within it better than than it can when it cools quickly. It cools far too quickly when it is welded with a stick electrode and pre and post heating techniques are not employed.
  
• Cracking that occurs is as a result of the cooling rate differential between the two metals. Nickel based electrodes are more successfully used for repairs as there is a bit of stretch in the nickel metallurgy and it is more compatible with the cast iron make up.

What I suspect occurred in the post above is that the particular cast iron piece that was welded was on the lower end of the carbon content scale and was not a particularly complex piece.

An example of what I mean by complex ,is that ,take a spoked wheel casting that was broken on a spoke- would present difficulties because heating and cooling on the narrow spoke ( As opposed to the thick areas of the rim and the hub) would certainly cause cracking

Any one that tries the technique described in the post above would be well advised not to attempt it on an irreplaceable item.The reality is that you will fail many times more than you will succeed as there are far too many unknown variables in the parent and filler metal make up.


Grahame