Tips/Techniques welding cast!!

[Megar arc 5040dd]

When I was in trade school as an apprentice one of the coolest things we did when learning to braze was braze up cast bevelled coupons in the vertical position. They were about 3/8" thick and 6" or 8" long if I recall. Once we were done they were put in the coupon bender, when the broke you had to have all broken cast showing along the joint with no braze showing. They made a loud sound when they broke compared to a normal welding coupon. It was a lot of fun I really enjoyed that part, I am really glad I had a good teacher who didn't just gloss over that subject since most of the class would never braze something thought their entire career. Oddly it seems to be a skill mostly carried on with hobbyists, no a lot of professionals do it much in their careers anymore. I assume because not a lot of shops take on doing small repair work.

 

[Megar arc 5040dd]

As others have noted, I’ve also had best results with torch brazing. Have done some field work with nickel stick electrodes, and have done some tig brazing.

This is a cast collar from a post lantern outside Osgoode Hall, downtown Toronto (cast iron doesn’t like it when you back a truck into it). Flux coated brazing rod, just what we had around.

View attachment 59632View attachment 59633

Lucky they found all the pieces for you to put back together again. That turned out really good.

 

[Stuart Samuel]

When I was in trade school as an apprentice one of the coolest things we did when learning to braze was braze up cast bevelled coupons in the vertical position. They were about 3/8" thick and 6" or 8" long if I recall. Once we were done they were put in the coupon bender, when the broke you had to have all broken cast showing along the joint with no braze showing. They made a loud sound when they broke compared to a normal welding coupon. It was a lot of fun I really enjoyed that part, I am really glad I had a good teacher who didn't just gloss over that subject since most of the class would never braze something thought their entire career. Oddly it seems to be a skill mostly carried on with hobbyists, no a lot of professionals do it much in their careers anymore. I assume because not a lot of shops take on doing small repair work.

That’s a great test!
I’ve certainly had steel tube joints fail in the tube rather than the braze joint, but that’s even harder.

I started out training as a goldsmith, which worked out well, in this respect. While there was any massive brazing work, there was lots of fine silver soldering, and torch control.

Lucky they found all the pieces for you to put back together again. That turned out really good.

Yes, I was lucky they did something about it immediately.
I think our client was the contractor whose truck hit it, so they were motivated .

 

[grease monkey]

ok, looks like only 1 way to find out! stand by for outcome!

 

[Tom Kitta]

I've had surprisingly good luck welding cast with 309L stainless filler, both TIG and stick.
I also use it when welding alloy steels. Basically, if the welds are cracking, use stainless filler. The low carbon content and (oddly) higher ductility make it quite forgiving.

I have tons of 308L or similar stainless rod - how does it compare with nickel rod which I have relatively little of? I weld cast at least few times a year, stainless supply would last me a lifetime.

Should I weld alloy steel (like 4330) with stainless rod as well for strength? I also have electrodes in the 10000 series - would that be better for alloy steel / cast?

 

[Ironman]

I have tons of 308L or similar stainless rod - how does it compare with nickel rod which I have relatively little of? I weld cast at least few times a year, stainless supply would last me a lifetime.

Should I weld alloy steel (like 4330) with stainless rod as well for strength? I also have electrodes in the 10000 series - would that be better for alloy steel / cast?

Try and find what works. I have seen a cast iron transmission case welded up with 7018, it was put in a fire and heated red hot, pulled the fire wood out of the way and welded, and then he poured a barrel of ashes over it to smother the fire and cool slowly. It came out just fine and was put back together.
The worst thing I ever welded was a WW 1 vintage shear of grey cast iron. I had to call Eutectic for help and they said use a non-machinable cast rod. They really did mean non machinable, man it was harder than the back of Gods head.

 

[Bandit]

Somewhere in the past, I read an article about welding cast, it was said/suggested to try the rod you were/wanted to use on the material and then try to chip it off with a hammer and chisel. Barring doing more damage, the weld material that stuck/held the best, was the one to use.
The worst cast I welded was an engine block, someone had tried to weld it before, the shop didn’t have an oxy torch, nor even a propane tiger torch. Lightly ground the surface, could not v groove as too dammed thin! Drilled small holes at each end of the crack that could be seen, started welding, short beads, weld about 1/2 inch, sometimes less, weld would start to foam up. Stop, peen lightly, grind foamy, porous, part off. Let cool down, change to a different material rod, think I was using some type of ni-rod, a stainless rod, 6013, 7018. A very slow PITA, job. The foam up likely caused by a somewhat poor cast material, in hand with who knows what put in the cooling system for many, many years. Never did get all the crack welded up, as it was just a chase, even a hole would not stop the crack extending, got it mostly done, put a layer of JB weld on, smoothing out the weld, and to cover any pits and cracks I had missed. Seemed the owner was happy, least ways never heard otherwise, was for a truck that was being restored, seems not another block to be had, (likely more $$$).
The choice of rod was what was available in the shop, and what would work, one type of rod would not keep working for what ever reason, change to another one after each stop.
Many years later, I was talking to a welder, he mentioned the same thing had happened to him. Thought the same as me, about metal contamination.
10000 series is generally for very strong steels, have heard of it being used for large truck rear end housings that are sometimes prone to cracking. You may not want a high strength rod/filler for cast iron, shrinkage rate and ductility is likely more important then maximum strength, something that will give and flex a bit as things cool. Often the weld does not crack/break, it is the metal beside the weld.
In some cases, ,I have heated cast iron up to 1200 degree F. (dull red), and held there for up to 6 hrs, (controlled oven), cooled in oven, would still have porosity problems when welding, in this case, Ni-rod 55 wire in a Mig.
Just my nickel’s worth, I am not a ticketed welder.

 

[JustaDB]

Often the weld does not crack/break, it is the metal beside the weld.

The two times I tried to weld cast iron w/ Ni-rod on an old Forney buzz box this is what happened.

 

[Ironman]

Somewhere in the past, I read an article about welding cast, it was said/suggested to try the rod you were/wanted to use on the material and then try to chip it off with a hammer and chisel. Barring doing more damage, the weld material that stuck/held the best, was the one to use.
The worst cast I welded was an engine block, someone had tried to weld it before, the shop didn’t have an oxy torch, nor even a propane tiger torch. Lightly ground the surface, could not v groove as too dammed thin! Drilled small holes at each end of the crack that could be seen, started welding, short beads, weld about 1/2 inch, sometimes less, weld would start to foam up. Stop, peen lightly, grind foamy, porous, part off. Let cool down, change to a different material rod, think I was using some type of ni-rod, a stainless rod, 6013, 7018. A very slow PITA, job. The foam up likely caused by a somewhat poor cast material, in hand with who knows what put in the cooling system for many, many years. Never did get all the crack welded up, as it was just a chase, even a hole would not stop the crack extending, got it mostly done, put a layer of JB weld on, smoothing out the weld, and to cover any pits and cracks I had missed. Seemed the owner was happy, least ways never heard otherwise, was for a truck that was being restored, seems not another block to be had, (likely more $$$).
.
Just my nickel’s worth, I am not a ticketed welder.

You got it down perfect. The foaming problem is often caused by contamination or carbon in the cast. Once Veed out, take a torch and set an oxidizing flame, and travel the crack heating to a dull red. You will see the sparks flying out of burning carbon, and the oil and antifreeze will be burnt out. And you have to peen the weld after every inch expanding it to stop cracking as the weld cools.

 

[MrWhoopee]

I have tons of 308L or similar stainless rod - how does it compare with nickel rod which I have relatively little of? I weld cast at least few times a year, stainless suppwould last me a lifetime.

Should I weld alloy steel (like 4330) with stainless rod as well for strength? I also have electrodes in the 10000 series - would that be better for alloy steel / cast?

The only way to know is to try. Ask 20 weldors how to weld cast iron and you will get 100 different answers. There are just too many different types of cast, and no way to identify what you have. As mentioned, try running a bead somewhere on the part in question and see if it sticks.

Regarding alloy steels, it depends on how critical the application is. If it just needs to hold together, stainless is generally reliable and uncomplicated. If it has to support someone 10 stories up, seek professional help. I'm no weldor, just a machinist who needs to stick a couple of pieces together now and then. I currently have to weld some hardened alloy dowel pins (actual composition unknown) to a piece of 4130. Originally I just fused them, but had one or two crack and fail. Now I add just a dab of stainless to the puddle. No failures so far.

 

[phaxtris]

really unless your brazing, welding cast is a gamble