Work in a cast iron foundry we use a Midalloy ENiFE-Cl self shielding fluxcore in our mig maghines .045"wire to repair castings. yes, preheat to around 500F with a torch, v it out slightly, peen between welds, slow cooling with a welding blanket is defiantly good or sand if you can use a little clay to make a dam around the weld. Then grind flat and take a piece of 1 to 1-1/2" flat bar about 1/8-1/4" thick. tack it in place on one end and heat and hammer the bar along the length, tacking along the way, weld all around the bar. banding it like this will make it alot stronger, i have personally repaired alot of old farm equipment like this and many of the repairs are still in use, best on being the tine of a old farmall side-dressing tractor.
People that do that sort of thing often lack the skills to fix what they f__ked up, fact is they can often circle the shop just ahead of you f__king up things at least 2 to 1 of what you can fix. I was the Unf__ker for a long time, sucky job.
Lots of threads here on CI welding. I have done it succesfully for decades. Not rocket surgery, but certain things must be observed..
Your piece. Vee out crack down to 1/16" land. Best to do from both sides, but working inside that housing may be difficult. Drilling end of crack is futile because you cannot tell really where it ends. Just vee an inch or two past where you can see it.
Play with clamps and shims unti you can close the crack (restore the geometry), without restricting access for welding.
Build a furnace for uniform preheat of the whole casting...bricks, sheet metal, wahtever yoiu have. Need to be able to close it up to heat nad cool own, and open a hole to weld through.
You can build a fire in your furnace with sticks...start slow to minimize thermal shock. You can use charcoal. You can use multiple small propane burners. But try to heat uniforfly, and take at least a full hour, two is better, to get the casting up to 600-1200 degrees F A barely visible dull red in the dark is about 800 F.
I use 1/8" ENiFe55 55% nickel rod. DCRP, about 125A 99% costs more and works no better. Bronze brazing works II, IF, IF, you get good tinning and flow..need good flux....
Weld less than an inch, peen with rounded point of your slag-hammer, or a long punch if access is difficult, until wed is no hotter than the preheat. Lay your next bead somewheree else. Repeat until all welded.
Operator will get COOKED, working for 2 hours right on top of 100 lb of 1000 deg iron. Suck it up, Buttercup. No shortcuts.
If you ned a break, close up the furnace and maintain preheat.
When done, close up furnace and bring back up to temp, pile the fiberglass blankets or ashes on so it will take the rest off the day and al l night to cool .
If you did the heat-and-cool uniformly enough , distortion should be minimal. Strength will be good-as-new (which was not good enough for the event that broke it)
You might consider reinforcement, but don't weld steel to the CI with short welds (Ilike someone already did)
LOTS of shortcuts exist for weldong CI...local preheat, special magic rods, weld-and-cool with no preheat. Lock-and-stitch and similar work for applications where strength is not needed, like cylinder heads, where most of the metai is just holding water in or making a flat surface for gaskets. All those processes unavoidably reduce the actual metal in the load path Try shortcuts if you like. The scrapyard will thank you.
You need the Paki fellow in the video from a post a few weeks ago, gas welding the cast iron engine block. Gas welding with cast iron filler will produce the best weld, if you can find someone who has experience. Brazing would be second.
You have needle scalers. Much superior to peening with a slag hammer.
I got started in CI welding with the square CI rods and oxyacetylene torch. Usually work on the dirt, too.....can't build a furnace around a big casting on the table, but of course I live in West Virginiastan
Badly oxidized castings like old exhaust manifolds sometimes can IME be welded no other way. But for good quality castings in good metallurgical condition like the OP's housing, SMAW is much faster and as strong or stronger than the original casting.
Current plan is to look for someone specializing in it, if I can't get a sense of anyone is actually great at it we'll do it ourselves with nickle rods. V it, 500 degree preheat, short welds, peening in between, slow cool under blanket. Within reason, don't care that much about the cost; this is production machine used to make a certain part so need it working, and the cost even of used rolls is frightening.
That should get us up and running, but I'm also going to sketch the the key dimensions so if it snaps again we'll be able to more quickly fab something
I'd not seen that metal stitching before, neat idea. I'm reluctant to use it here as there would be a lot less cast iron in cross section that would have to break than the original casting.
thanks again...will take pics and let you know how it works out
ive done a ton of cast iron repair, and only about 1.5 hrs from toronto. its a pain and needs to be ground out in the crack, and cleaned, clean clean clean! 99% nickel rods i have also and run about $80/KG and can only buy 5KG packs
will probably be an all day job heating it up, and welding it and then having it cool slowly. love my wood stove for this as it heats it right to 500 degrees on top and slowly cools for hours. if you can take it completely apart that will give anyone the best chance to fix it.
and i wouldn't braze it as that is just for good looking welds that aren't strong.
there is also some other filler that is good on cast iron, but its hard to find sometimes like muggy weld