Tig welding cast iron? Is it possible?

Nathannamaya · Wed Dec 16, 2015 1:07 pm

Hey guys! I've got a customer who needs a cast iron part welded, and I wanted to know if would be able to tig weld it? Or if I would need to pull out the trusty buzz box! If I would be able to tig weld it, would it be just as strong of a weld as arc? And what would be the procedure to tig weld cast iron? Any advice welcome! Thanks guys

dirtmidget33 · Wed Dec 16, 2015 2:09 pm

Of course it's possible depending on the part and filler options you have or if willing to buy the needed fillers. Can you post pics of part and damage needing repair. The more details you can give us about part the better. Also is it exposed to high heat cycling and stress, is it just cosmetic repair, load bearing etc. Several ways to repair some are easier or harder depending if brazing, welding. Will it require preheat and post heat cool down procedures. These requirements change as needed to make it serviceable again. So if you can get us pics and part details sure someone here has repaired something similar and can offer advice.

big gear head · Wed Dec 16, 2015 7:16 pm

I've TIG welded several cast iron rear end housings for cars. I used N99 wire, ground the surface of the cast iron so that it was shiny and preheated to 500 degrees.

Nathannamaya · Thu Dec 17, 2015 12:32 am

dirtmidget33 wrote:Of course it's possible depending on the part and filler options you have or if willing to buy the needed fillers. Can you post pics of part and damage needing repair. The more details you can give us about part the better. Also is it exposed to high heat cycling and stress, is it just cosmetic repair, load bearing etc. Several ways to repair some are easier or harder depending if brazing, welding. Will it require preheat and post heat cool down procedures. These requirements change as needed to make it serviceable again. So if you can get us pics and part details sure someone here has repaired something similar and can offer advice.

They're spindles for a front susoension on a car, he wants about an inch removed out of the part, so it's basically going to be a cut, bevel, and weld.

ex framie · Thu Dec 17, 2015 1:14 am

Walk away, dont do it.
These take a fair load, when it fails its your bum in the sling.
In Australia there is NO welding allowed on suspension or steering parts for the reason as its near impossible to ensure the part has been welded correctly, ie not with a cheap 90 gassless MIG etc.
He would be much smarter to have the pieces manufactured/ machined not welded.
Its your arse and whoever gets injured /killed when it fails, is it worth it for the $100 or so bucks you'd make on the job?
I'm not personally attacking you, it just some things shouldn't be welded.
Thats my opinion yours may differ.
What do you reckon?

Arno · Thu Dec 17, 2015 2:42 am

Nathannamaya wrote: They're spindles for a front susoension on a car

In that case they may actually be cast or forged steel, not cast-iron, as the steel will be more resistant to the shock loading and bending forces experienced by these kinds of parts.

Quick check would be to test like Lody did on a few of his video's and puddle an edge of the cart, let it cool and then use a file to check how hard it gets. If the melted piece becomes rock-hard then it's likely cast-iron. If it remains soft then it's likely a steel type of some kind.

Bye, Arno.

ldbtx · Thu Dec 17, 2015 9:36 am

Some of the best advice I ever heard is, "The key to success is knowing which jobs to walk away from". I'm with ex framie on this one. I wouldn't touch it. Too much liability and chance of hurting or killing somebody. Wouldn't it just be easier to get a machinist to chuck it up in a lathe and shorten the outer end and rethread it?

big gear head · Thu Dec 17, 2015 2:18 pm

I doubt that it's cast iron. Probably cast steel or forged steel. What kind of car is it?

dirtmidget33 · Thu Dec 17, 2015 4:32 pm

I would RUN away from this one. Out of curiosity is he wanting to shorten the shaft by an inch or lower the spindle shaft. What is the reason. If lowering someone prolly makes a lowered spindle already that could be adopted to vehicle. As others stated these are not cast iron but forged and cast steel.

Just so you know. There is some spindles that do get welded on. Perfect example is some stock car spindles that have bolt on steering arms. Some teams have these steering arms welded and bolted. The difference is these are normally 4140 chromoly so they know what there made from and they have tried and trusted methods worked out for them on doing this. Not all bolt on steering arms can be welded (just so no one gets idea to start welding on bolt on steering arms) They also require preheat because the parts are so thick and will crack the welds if not done, plus heat treatment. So like i said they have methods in place on how to due this. I dont know all particulars on the methods used. In the open wheel world we have bolt on steer arms that are aluminum bolted to an aluminum spindle with steel shaft.