Welding Cast Iron

[Screwdriver]

I just bought this

Cheap because it needs some repair. I'm thinking of brazing that small snapped casting. Would welding be "better"?

S.

 

[Bill Edwards]

I always go for welding.
Cold (properly cold so you can put a hand on it) and peening - it always works. What's not to like?

 

[Screwdriver]

I always go for welding.
Cold (properly cold so you can put a hand on it) and peening - it always works. What's not to like?

MIG or TIG? What filler?

S

 

[Bill Edwards]

MIG or TIG? What filler?

S

Stick, nickel rod. Can't do it cold with a tig as you're putting heat in just to get things to melt.
With stick you just do maybe one inch (on a large piece) then stop to peen and it's keeping it as cool as possible.

 

[Richard.]

Can't do it cold with a tig as you're putting heat in just to get things to melt.

Can't do it cold with a tig as you're putting heat in just to get things to melt.

You can!
All my cast iron repairs are done with tig and depending on part size will depend on whether I weld hot or not.
You need to melt it despite the welding process.
Weld it like your reducing distortion. Bit of current travel fast stop peen cool continue.

 

[TechnicAl]

Personally I think Stick is the best cold welding method. TIG can put too much heat in. If you are aware of this you can compensate but it needs more skill. MIG is also good but you have to buy a lot of wire at once.

Most Iron is the Nodular or Grey type which is remarkably quite weldable (given consideration)
For the less weldable Irons stick will give the most consistent results

 

[Bill Edwards]

You can!
All my cast iron repairs are done with tig and depending on part size will depend on whether I weld hot or not.
You need to melt it despite the welding process.
Weld it like your reducing distortion. Bit of current travel fast stop peen cool continue.

Well to a point I'll say fair enough as you're the TIG man. But, it cannot be as cool as stick as once you strike an arc with stick you're almost immediately melting everything. Plus the stick rods are designed to run at lower amps and surely TIG is by nature a slower process - so you might be able to keep it cool but each run will have to be shorter for the same heat input?

 

[Richard.]

The heat input with Tig is higher yes due to slower travel rates and I'm not or haven't said its better than mma I just said I use Tig only to repair it and you can weld it cold. The consumable for Tig also allows you to treat it with lower current rates although probably not advised to go too low as you want to increase your travel.
Remember the process correction factor with GTAW is lower than mma. Yes the heat input is higher but there isn't that much in it current for current.
I prefer Tig because it's better for those intricate cracks where you can easily follow those fine lines.

I was only only disagreeing with your quote "you can't"
I beg to differ. You can.
I'm not a Tig man I can just Tig weld like many others on here. No better.

 

[Bill Edwards]

I was only only disagreeing with your quote "you can't"
I beg to differ. You can.
I'm not a Tig man I can just Tig weld like many others on here. No better.

Don't be so modest, you're good at TIG...

 

[Chris Stevens]

Wonder why any need to weld cast iron if it can be repaired using brazing? Have managed to do a lot of cast repairs no problem at all using Sif No8 with DC tig. Tig brazing is faster, easier, and filler is less costly than MMA rods.

 

[Bsmith]

Last cast iron repair job I did was a lug that holds the bronze bush on the countershaft bracket of my boxford. I did it with oxy/acet brazing. When I was finished the brazing I found it was a little out of alignment, so reheated the braze and moved it to where it should be. If I had welded it with stick I would not have been able to re-adjust after the repair.

 

[Shox Dr]

I'm in the middle of repairing this



It's on the mill at the moment


SIF No8.

Its my 'goto' rod. If I'm in doubt No8

 

[Chris Stevens]

No 8 seems to do pretty much any CI repair no problem, and seems to be a better choice for dirty castings such as exhaust manifolds than nickel MMA rods?

 

[Richard.]

I'm in the middle of repairing this

View attachment 92471

It's on the mill at the moment
View attachment 92473

SIF No8.

Its my 'goto' rod. If I'm in doubt No8

That looks a nice little job your doing there shox.
Don't forget to put some finished pics up of the repair.
Nice to see some proper prep work been done

 

[Bill Edwards]

Wonder why any need to weld cast iron if it can be repaired using brazing? Have managed to do a lot of cast repairs no problem at all using Sif No8 with DC tig. Tig brazing is faster, easier, and filler is less costly than MMA rods.

Using MMA I can repair anything of any size, just about anywhere - and all with just a buzzbox welder.
Take an engine block with a crack. If it's in a position I can get a rod to it's mendable in probably a couple of hours.
But to braze it'd need removing from the vehicle, completely stripping and heated and cooled carefully. Sometimes I can't see why you would braze when you can use welding!

 

[Screwdriver]

This is the casting which needs repair.

It's very thin for a casting and is the hotplate for a dual fuel stove (wood/coal). I have successfully brazed castings before, using the hot method to fix a jaw onto a vice (it's super strong incidentally). In this case, strength is not the problem, it's delicate enough anyway and is just a simple flap. I have done a fair bit of TIG welding and even some TIG brazing but I'm not that good - the Kemppi AC/DC machine I bought as a project and fixed up flatters my entry level skills. I do have a decent MIG but my stick welding is pretty dreadful.

I have some silicon bronze filler rod and knowing my skill level, TIG or Oxy brazing is probably my best bet unless someone tells me otherwise... I have oxy/acetylene too so am spoilt for choice really (which was the whole idea!).

The part is currently in an electrolysis bath and I'll have a crack at it tomorrow. No pun intended. So having seen that part, whaddya all think?

S.

PS I am videoing the whole restoration process as a test because I am aiming to start my own YouTube channel.

 

[Shox Dr]

That looks a nice little job your doing there shox.
Don't forget to put some finished pics up of the repair.
Nice to see some proper prep work been done

Thanks. Unfortunately not a paying job as it's off my truck. The part was oil soaked, scum in the weld made it hard to read, needed a good clean up after tacking. You can see the contamination in the photo, I dont think its going to fall off anytime soon

 

[TechnicAl]

The Nickel rods provide a much stronger weld than the Tin Bronze "weld". Having said that the cast iron wont have much tensile strength either. For the common grades the difference isnt that much. However thicker stuff wont braze well unless heated and if there is large section differences the heat can cause it to crack. If the weldability of the iron is particularly poor the Nickel base will be more successfull.

 

[Chris Stevens]

Using MMA I can repair anything of any size, just about anywhere - and all with just a buzzbox welder.
Take an engine block with a crack. If it's in a position I can get a rod to it's mendable in probably a couple of hours.
But to braze it'd need removing from the vehicle, completely stripping and heated and cooled carefully. Sometimes I can't see why you would braze when you can use welding!

Never ever needed to pre-heat or post cool using tig brazing, and just find it an awful lot easier and more effective than MMA. If you only have MMA though its obviously the go to method, and a good idea for thicker castings where more heat is required, or where brazing isnt suitable.

 

[Chris Stevens]

This is the casting which needs repair.

It's very thin for a casting and is the hotplate for a dual fuel stove (wood/coal). I have successfully brazed castings before, using the hot method to fix a jaw onto a vice (it's super strong incidentally). In this case, strength is not the problem, it's delicate enough anyway and is just a simple flap. I have done a fair bit of TIG welding and even some TIG brazing but I'm not that good - the Kemppi AC/DC machine I bought as a project and fixed up flatters my entry level skills. I do have a decent MIG but my stick welding is pretty dreadful.

I have some silicon bronze filler rod and knowing my skill level, TIG or Oxy brazing is probably my best bet unless someone tells me otherwise... I have oxy/acetylene too so am spoilt for choice really (which was the whole idea!).

The part is currently in an electrolysis bath and I'll have a crack at it tomorrow. No pun intended. So having seen that part, whaddya all think?

S.

PS I am videoing the whole restoration process as a test because I am aiming to start my own YouTube channel.

Tig brazing with No8 is the perfect way to repair that. Be aware that OA and tig brazing rods are quite different though, and OA rods no good for tig.