Welding cast iron

[Meep-Meep]

Well, the deed is done....outside in the rain and cold, wet feet, under a canopy with super assistant Mongo at my side.

A bag and a half of Kingsford got that thing up to 450 F in less than an hour. The heat was even and eventually got to 560-ish when I started welding. The right rear got to about 750 while the weld area was about 900 or more. At that point I switched to the rosebud to heat up the back area to keep the delta T under control then changed back to the #2 and kept welding. My left hand started feeling a bit warm, particularly the pinkey finger, and when measured with the IR it was 280 F at the glove!! I need ceramic space shuttle gloves!! I started this about noon and when I left at 8:00 it was 470 F. I think its cooling nice and slow - just the way we like it. The BBQ did it's job perfectly so the question remains if the weldor did his....and I'm not claiming success until I find it's not broken or cracked worse than it was. Only one regret is we didn't have burgers ready!

The BBQ is a home made job that my buddy Marc folded up in about 5 mins - probably while half asleep and watching Iron Man (yeah, he's that good). This thing went from concept to lighting the Kingsford in less than two days. Building this reminds me of working at the lab - except the part where it takes six months, three engineers and 47 design and safety meetings to build.

The filler material I used is a special poured cast rod that you use with flux. Very slow process but it works great. I say go for it! Fix those broken HEMI manifolds in your BBQ!

Just thought I'd share an interesting experience.

 

[rumblefish360]

OOOOOOOOOOOOOOOOOOOOOOooo sparkles, I like sparkles.
Whatcha weldin?

 

[68 Satellite]

What IS that you're welding? A couple questions after you heat that and let it cool doesn't it make it softer and need to be reheated and cooled again? Also where I work they weld cast iron all the time with out preheating it. One part has a robot doing it with a mig of some type.

 

[Meep-Meep]

I have no idea other than it's a $3000.00 transmission case from some tractor. Yup, I was sweatin' it! The other part is a 390 GT manifold.

The thing I was always told about cast iron is to preheat it and cool it slow so it doesn't crack and I never heard anything about heat cycling it after the weld. I think it's pretty stable stuff if you treat it right. Maybe it depends on the grade of iron on how much you can get away with, but I didn't want to take the chance.

The common way to weld it is to arc weld it using a nickel filler rod but you are limited to short welds because the nickel does not expand and contract at the same rate as the iron, and on cool down there will be unequal stresses that can cause problems. I ran a pass on an old brake rotor using the nickel rod and no preheat and the weld bead just peeled right off and took some of the iron with it! I'd be interested to know what kind of cast material your guys are welding and also the process. I used to run a vacuum brazing shop for a national lab and had to deal with different materials at high temps all the time, but that doesn't make me an expert in welding. The cast rod should be a dead on match regarding materials and the softer gas flame should be nicer to the part during the process. Try it out!

 

[daredevil]

I love these threads that are educational. Not your ordinary I bolted this on and it went this fast. Great thread,thanks for sharing.

 

[69 Runner]

But I just bolted this on and it went this fast (he said with a tear in his eye caused by the new knowledge that no one cared).....:sigh:



:tongue:

 

[Rob R]

I have an old gristle haired guy(he's in his 80's) that welds my broken cast iron...He has a huge tub of steel beads that he puts the parts in first and heats the whole part before he welds it and then another tub of beads that he lets the part cool in.The welded part cools very slowly for over a day (24 hours) He's great for cyl heads.

 

[Meep-Meep]

Gotta love those old gristle haired guys!!! If it wasn't for them we wouldn't know how to do anything. I hope to be one someday!

Next up on the cast iron welding episode will be an original 427 Ford shorty header that has some really ugly cracks in it. I'll keep y'all posted.

 

[68 Satellite]

:rolling: I am so far from an expert that it's funny.I work in a factory that makes fire hydrants and water valves.I run a CNC machine that makes the stems that open and close them. The bodies are made from cast iron. There are several types of iron but we only use cast iron and ductile iron. Ductile is used mainly for the attachment parts as it is much stronger than the standard iron. Most of the time if a part is defective it is just scrapped and remelted. The bigger and more expensive parts are sometimes welded if possible. Not sure of the rods and whatnot.We are closed now for 3 weeks due to the housing slow down No new houses=no new hydrants .I had a friend bring in a manifold that had a rusted broken bolt it in that the tool room heated and removed the bolt. After it had cooled he reheated it and put in a pile of hot cast iron shavings for 8 hours to coll as he said it would be brittle otherwise. I don't know if thats right ,just telling what he said.Got to be someone on here that knows. It seems that B-Bodys only is starting to get more members :grin:

 

[Meep-Meep]

I suppose he was stress relieving it because it cooled too fast? Like you said I'm sure he knows what he's doing.

I brazed a crack in a 440 head many years ago and I just preheated it on a steel bench with a rosebud until it was a blue/purple color. After the repair I stuck it in a can and buried it with sand so it would cool slowly. The head had seats installed and they didn't fall out during the heat cycle, and as far as I know it was bolted on and drove away.