Welding Cast Iron

[Screwdriver]

That's kind of a shame... He's a bit, erm, opinionated (but so am I tbf).

I've had a couple of bits off him and they were as described or better, so y'know, one bad report and all that. My dealings with him and the one mentioned above make a 66% positive feedback score

I did mention the "sting" to the mods some time ago in private but I'm over it. Surprised to see it resurface, especially since oxy flame welding is not a process for joining breaks so far as I have been able to establish. But I was asked a direct question in an open forum and I suspect there was some behind the scenes robust communication which resulted in this development. I bear no grudge.

Since the cast part under repair is so thin, I am thinking of putting a bevel on one side only and clamping it firmly to a flat bar before welding. I would practice first but at £2 a pop, I'll practice on the part!

S.

 

[eSCHEn]

Shame Where will I get my daily downer from when I'm feeling too happy now?

 

[Screwdriver]

Is that £2 a pop for rods or replacement parts?

What happens if you try to save £4 worth of practice and shatter the part?

Haha, well the part is irreplaceable so I guess that makes it priceless. I'll have a quick practice with some regular stick on a bit of flat plate but yes, I'm just going to "getter done".

Heck I've watched so many videos from Jody at weldingtipsandtricks, I started to develop arc eye. It'll be fine and if not, I can blame Bill.

S.

 

[Bill Edwards]

Haha. Have a practice with normal rods first if you feel a need to, the CI rods aren't actually hard to use.
Very short runs and keep peening the weld with the chipping hammer and it's hard to go wrong.

 

[Bill Edwards]

Don't miss the weld while peening - that can make it go wrong on a thin section

Good point

 

[Screwdriver]

Well I did a few practice runs on steel, no worries.

Set to 50A DC+ rods go in like butter, weld tuns up lovely, tap tap with a peening hammer.

Then ten seconds later it inevitably shatters into a thousand pieces like an old eggshell. I say "inevitably" because when you actually work on the piece, watch the molten pool solidify as you peen it, it's obvious what happens next to 3mm of cast iron. It will shatter.

I should have stuck to what I know would work. Get it hot, get it brazed, cool it slow. It's not me being cack handed and 50A was about as low as it would go and strike an arc. I was doing 5 seconds/10mm runs. If anyone here wants to try, I'll let them cut a slice, weld it up and I'll bet £100 it will shatter.

S.

 

[Bsmith]

were you using cast iron arc rods?

 

[Screwdriver]

I will be more wary of taking any advice thanks.

 

[Screwdriver]

Yeah, well, live and learn. It is still in one piece although rather fragmented. I've tidied it up a bit now and I may even try welding it hot and keeping it hot. Or I may just go with a braze. It's not a critical part and can easily be copied/fabricated but it's a shame but hey, it was already broken...

As has been observed, there's only so much peening you can do on such a thin piece. I would run a very short bead, then immediately start peening the weld. In the last pic you can see the part has tried to lift, twist or buckle, despite having a "good" tack on there.

S.

 

[brightspark]

should have heated the lot up with a propane torch and brazed it with oxy acetylene I've done a few cracked water pumps doing it no bother

 

[Screwdriver]

should have heated the lot up with a propane torch and brazed it with oxy acetylene I've done a few cracked water pumps doing it no bother

Yeah, I got talked out of it. Not too difficult to do because my oxy kit is decidedly dodgy. Plus I was game to give it a try.

Would I have to grind a V out or would sufficient braze wick into the crack(s) d'you reckon? I could always drill a few holes I guess.

 

[Bill Edwards]

Hmm. It sounds like you did it right.
I don't see why it didn't work, what's the difference between that and an old exhaust manifold...?

 

[Screwdriver]

A tube or cylinder shape would be less prone to buckling and is an inherently stronger shape.

This is flat and thin. Hindsight is a wonderful thing, next time I'll use it first...

 

[Bsmith]

If the casting has been used inside an old stove, there is a good chance that it is impregnated with coke/soot as cast iron has a very open grain compared to steel. OA brazing/ welding may be worth a try but I wouldn't promise success.

 

[Richard.]

I will be more wary of taking any advice thanks.

I think that's a little out of order SD.
Looking through this thread there are many suggestions on how to weld CI (Mig,Tig, mma, braze etc).

You chose to mma it based on some of that advise.
You could of picked any of those processes and the same thing happened.
A part that small I would of heated and welded hot because it's very difficult to weld small parts cold.
I don't believe the process was at fault here.
Rods unlikely either.
Peening well if you were beating hell out of it then yeah that will do it but otherwise it hasn't caused your damage.
I would hazard a good bet that uneven temp has caused this and had you got it all really hot before striking up it wouldn't of buckled and probably be in 1 piece.

 

[Screwdriver]

I think that's a little out of order SD

Think you should look at the post I am replying to.

"Just mig it"

Which I assume is tongue in cheek.

 

[Richard.]

I saw the post.
I also feel rather gutted for you it's gone pear shaped.
It's very difficult on open threads to know which way to go as there is always loads of different answers and as you've no doubt guessed everybody is right with a sucsess story to back it up.
If you wish to send that piece to me as it is I could have a look to see if it's salvageable but it doesn't look promising.

 

[Monkey Harris]

My 1st cast iron welding experience ..

I've just mig welded a side plate from my 22 year old Jotul stove,
Probably good quality cast iron...

It had a hairline crack 3/4 of its height .
It cracked after 14 years, as I did not know there were burn plates missing..

I heated the plate in the oven for 10 mins,
Then placed it on the bench on top of its brother..
I then put a cooker grill element between them, and turned it on,

And kept them both hot..
too hot to touch..
A piece of towel, I put on it between weding caught fire...

I turned the mig up to around 200 amps and put 5 or 6 ,
1" long welds along the crack ( I had put a v groove in it. )


I let the welds cool a bit then finished welding the rest, it was a 10" crack.

I the wrapped up the whole lot ,
plates and element in a couple of towels and old coats

It took 4 hours to cool...
During this Time there were a couple of pings...

I've gone all over the weld hitting side on it with a tack hammer and it seems very solid

Time will tell if it survives the woodburning this winter,

But it cost nowt..compared to £180 for a new plate

 

[Monkey Harris]

the completed weld ..

 

[HughF]

The one thread I haven't clicked on till today...