Welding rod for cast iron?

The gent offering a rod assortment on ebay got me thinking...Ive only made repairs with brazing rod on cast iron, worked pretty well. But I know that there are electrical welding rods for cast iron that can be used on buzz boxes and other small home AC-DC welders such as the Lincolns etc.
Anyone have a preference for any particular rod for repair of cast iron stuff? For example..building up the corner of a lathe compound or a cracked apron, or a busted bandsaw wheel..that sort of thing.
Gunner
'If you own a gun and have a swimming pool in the yard, the swimming pool is almost 100 times more likely to kill a child than the gun is.'" Steven Levitt, UOC prof.

I haven't done anything too impressive with it, but I've used 99% nickel to fix older castings. Works well, just peen as it cools. Repaired a DP belt guard pretty well this way.
GTO(John)
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they sell ni rod for cast iron but i like to use stainless with a hi nickle content. saw blade wheels do not weld well, you definatly need to preheat the wheels or they will crack in different places.

When repairing cast iron the acceptable rod to use is a ni-rod which is nickel. This will produce a machineable deposit. Other rods are used but you risk a hard deposit that is not machineable. They are not worth using for the slight saving in price. I have had good luck repairing with brazing rod however it is labour intensive and you have to do a lot of preheat and post heat. With ni-rod you can stitch if the casting is large and intricate by running no more than an inch at a time and peening the bead as it cools then waiting until the casting cools to room temp before putting in another inch stitch. The other way is to follow preheat and post heat similar to brazing. Building up the edge of a compound is not difficult. Once you are involved with things like spoked wheels the shrinkage stresses can easily result in cracking after the repair is done and it is cooling. The last year of my apprenticeship the owner of the shop would not allow any cast iron repirs done with Ni-rod. Everything had to be brazed. By the time I left I was pretty good at brazing cast iron and started to prefer it over stick welding. With cast iron procedure is everything no matter which process you use. Randy
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Randy Zimmerman wrote:(clip) The last year of my apprenticeship the owner of the shop would not allow any cast iron repirs done with Ni-rod. Everything had to be brazed. (clip) ^^^^^^^^^^^^ I am interested to know what your boss's objection was to stick welding CI. I am a NOVICE welder with decades of experience, and I have recently discovered how easy it is to stick weld CI with the right rod. I didn't even know you're supposed to peen, and yet everything I have done has been OK.

Old Peter was a product of the Thirties and had his own way of doing things. He did cold stitching on larger casting such as engine blocks. It is time consuming but there is not heat involved. There are still outfits repairing using that method. I imagine previous welders he had working for him had screwed up when arc welding cast and he blamed the procedure rather than the operator. Brazing is a reliable repair in that you see what you get. If you are not getting a good bond to the cast iron it is very apparent as you lay the filler rod in. The brazing alloy is a good match on strength with cast iron. The problem with arc welding cast iron is that people tend to cheat by rushing the job or having inadequate preheat before they start. If you are doing short welds and peening without any preheat you have to be patient. People often put a few short welds in and peen. Then they get impatient rationalizing that the repair is cold enough for another weld. "Hey! It wasn't red anymore and my arm hurts from all the peening" When Peter went on his hunting holidays I would arc weld cast iron fractures for farmers coming in. It was cheaper than brazing because I would only charge for the welding and peening. It would take all day to do the job but I would only spend fifteen minutes total doing the repair. I would go over and run a small bead, peen and go away to my other jobs. The idea of peening is to stretch the weld bead as it cools. That counteracts against the shrinkage forces. With mild steel shrinkage forces bend or stretch the steel but cast iron does not stretch or bend very much before it cracks. The design of casting always takes into account how the piece will cool in the sand. Often castings have unusual heavy sections to cause the casting to solidify and cool evenly. If casting is heavy and massive at both ends with a small section connecting the casting will crack and never see full production. When welding cast iron one has to take this concept into consideration. Randy
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CI.

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I have had good luck with UTP Econocast 55 and 75. Also I have been pleased with Certainium Cast iron electrode.

On Sat, 27 Dec 2003 09:23:01 GMT, Ernie Leimkuhler
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Many thanks Ernie. Standard Preheat, post heat and peening I assume?
Gunner
'If you own a gun and have a swimming pool in the yard, the swimming pool is almost 100 times more likely to kill a child than the gun is.'" Steven Levitt, UOC prof.

The NassauRockmount "Jupiter A/AAA" series is similar to the Certainium 889 rod if I recall correctly. They are a good general purpose 55% nickel rod with good welding characteristics for almost all types of weldable cast iron. Excellent on dirty or oily cast iron.
The "Jupiter B/BBB" series is 99% nickel. A little more sensitive to the condition of the base material being welded, but should be more machinable. The BBB version has a non-conductive flux and won't side arc... handy for getting into tight spots. I was always able to weld multiple passes of B/BBB over it's own slag without porosity problems.
Yes - preheat, peen, and post heat would be helpful I should think. Keep in mind that some grades and types of cast simply aren't weldable, and brazing would be required (but that represents an entirely different set of problems).
Dave
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Lincoln 99% NI NI-Rod. No heating, just peening .
Tony
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Gunner,
By coincidence I tackled my first cast iron welding project today. My inept twin broke the motor mount on an antique woodcutting bandsaw while unloading it. I used 99% nickel rod and it "seemed" to weld very nicely but I think it's a similar case to MIG welding, where it's easy to make a pretty bead, but a pretty bead doesn't necessarily mean a strong weld. I tacked it in a couple places first for alignment. I didn't get it quite right, and in tapping it lightly to line up the parts, the cast iron surrounding the tacks was very brittle and broke. I think that is the weak link in welding cast iron, the stuff is not very flexible! Clearly, pre-heating and peening is important, and I think also slow cooling.
The books I have all mentioned the importance of removing all casting skin and vee-ing the crack or parts.
Bob

I won't even claim to be a knowledeable welder compared to those more formally educated in the art, but I've had some pretty good results on cast iron pumps and such by preheating with a rosebud, then DC tigwelding using nickel stick rod with the flux ground off, for filler. After welding, warmed again with rosebud and let benchcool. Also did the same process using a tig rod someone gave me called Ever-dur or some such. (Silicon based, I think). Also tigged up the holes someone had drilled in the body of a '40 Ford truck I was street rodding with it.. Stuff puddles like putty and is very manageable in controlling droop and fallout. Stuff tigs well on galvanized steel, too. Just don't breathe while welding. :)
RJ
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Preheating and post-cooling are critical on things like a spoked wheel, such as Gunner was contemplating, but really not very necessary if the part can cool without developing stresses. If you are welding a spoke, the rest of the wheel prevents the spoke from shrinking as it cools, so it goes into tension. As we all know, CI has practically no tensile strength (great in compression, though), so it will crack. If you are welding the broken lug on a bandsaw base, it can cool without stress, so there's not too much to worry about.

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Funny, I was under the impression it often had 30 to 60kSI, comparable to mild steel. Now, plastic deformation, it hasn't...
Tim
-- "That's for the courts to decide." - Homer Simpson Website @ http://webpages.charter.net/dawill/tmoranwms

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Leo,
Thanks. That makes sense. The welding is finished, and I'm almost tempted to break it again just to see how strong it is and where it breaks. But I'm not gonna.
Bob