Welding Cast Iron

After watching the progress on Mammoths Cylinder blocks to only be cut short when we were heading towards the finish line, wondering if anyone else has had any success with welding/fixing cast iron.

When i worked at Dunlop/Olympic Tyres at Footscray (Mid 80's early 90's) we had a large welding set up.
To weld cast iron, there was a large furnace that the would heat up the item that required welding, they would then take it out and start welding keeping a very close eye on the temp of the item once the temp started to drop it would go straight back in the furnace and this was repeated until the welding was finished, once finished the item was put back in the furnace and the temp would slowly be dropped over the next few days.

The welders worked miracles on some of these jobs and as i had to machine some of these welds afterwards it was great not to have that glass like hardness on the join of the parent material and the weld.

Not sure on what rods were used but some jobs required shifts running 24 hours a day until the welding was completed.
Very time consuming but when you need to get cast iron welded what choose do you have.

I run into the old Welding Foreman about once every 12 months next time i do i will ask him what rods were used.


Trevor

Strata have some pretty good rods.
I welded a replacement linkage bracket onto my DB 30D tractor nearly 30 years ago and it's still good.
Also used them on an exhaust manifold on the Terry

I remember some time back a friend was getting a major bracket repaired for a traction engine. It had many cracks in it. To repair he found a bloke that specialises in cast iron repairs and did similar thing to what you indicate SloSpeed.

From memory the sequence was where major crack the crack was ground out to allow full penetration. The casting was then set up on firebricks and covered with appropriate rated insulation mat then heated up slowley till red hot. Then the welding rod was basically melted into the crack (don't know what was used). So to me seemed similar to brazing the crack. Care was taken to keep the casting hot so the cracks had to be repaired bit by bit.

Once complete as you indicate the the whole casting was carefully lowered.

Very slow and careful. But must have been the same procedure you discuss SloSpeed.

Would be great to hear what was used!

Been many years since i've done any welding but i remember something about keeping the heat into it with the oxy and welding backwards . Instead of just welding like normal you weld right to left in small steps of about an inch ?.

If my memory serves me right I think Scummy is correct. I am sure that was how I was shown many many moons ago

Just found a site discussing cast iron welding (even though they are advertising some other process).

It mentions a couple of different methods. Might be of interest. www.metalockaustralia.com/welding_castings.php

Apparently the method of welding depends on the metal composition of the casting.

We sent a "cast iron" engine support bracket up to a well regarded welder on the central coast of NSW. He had problems with it, and we had to get it sent off for metallurgical testing, so that he could determine what process to use.

Could always try mig welding if not a critical component. I had success welding up some parts of my metal lathe after dropping it off my trailer. I heated the parts in an old oven. Here's the site where I got the idea from
www.mig-welding.co.uk/cast-iron.htm

Think it depends on alot on the age. I expect older cast iron is probably going to have a lot more carbon in it than newer mixes.

But sounds like the pre-heating to relive the stress of the cast iron when the weld cools might be the secret. And the vital cool down slowly to ensure no hardening of the cast iron also vital.

Beaver

You are spot on about the composition i remember sometimes we would grind a small piece of the casting and send it away to be annalised.
I know by having to machine a lot of cast iron it does vary a lot from the soft grey cast iron to the stuff that use to squell like a girl when you machined it,(I can hear it ringing in my ears now).

Trevor