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Welding on cast iron with MIG?

dremu

dremu

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Welding machine is a Lincoln wire-feed with gas... SP135, I think?

Anyway, I've only done regular steel, not cast yet ... and my parts ShopSmith has a coupla cracked parts that need some love... is it doable with this hardware?

-- A
 
Probably not. From what I know, you need to preheat it and use a fairly powerful welder.
 
Cast is done with stick, area to be welded is pre heated to about 325 degrees, welded then once welding is finished it has to be wrapped with insulation and cool very slowly. The room you are welding in should be warm too and before any exterior door is opened make sure your cast is wrapped, sudden spurts of cold air can cause recurring crack. Another thing is that your surface to be welded should be "V"ed out and drilled at each end of the crack to prevent it from getting any larger, the "V"ing is just to insure proper penitration.
 
-Not a welding expert, but I think Arc is used because cast is usually done with a Nickel rod.

Although I have done non-critical welding (old bench grinder base) with nothing more than an Arc (DC) welder, 6013 (regular, nothin' special) rod, and alot of patience. No prep whats-so-ever, pre or post heat, just lay down a 1/2" bead and let it slowly cool. Maybe I was lucky.

Hey, it wasn't my grinder :D
 
Brazing cast iron is going to yield better results, but it is more of an art than anything, takes years of practice.

If you are going to try it with limited experience and tools, try drilling a very small hole just beyond the visible end of each crack(both ends) as was already suggested above. This will stop the crack from continuing. The welder you have will work, but you'll need to set it up for flux core wire, as this will aid a less powerful welder in penetrating a bit deeper.

Try not to grind your welds after, as this will reduce strength in the affected area.

I could go on four 10 pages, but this should help a little.
 
i have tried welding mild steel to cast with a MIG, it didn't hold. once i set it down with the weight on the weld, it broke off. it looks like i didn't even weld it to the cast, nothing on the cast at all, they were only spot welds.

i have to weld up my adapter and going to do it with nickel rod and my lincoln ac225, hopefully i have better results.
 
Nickel rod is correct.. pre heating is correct... stick is correct...

Welding clean cast iron is acceptable in non critical situations... however parts like exhaust parts dont weld well because of carbon contamination

Welding cast with mig is possible but not with a little machine and not without a roll of very special and expensive wire

Find someone with a buzz box...
buy some lincoln nickel rod... a five pack is cheap... v groove.. use a heat stick if you arent sure...pre heat and post heat and follow the rod recommendations
 
dremu said:
Welding machine is a Lincoln wire-feed with gas... SP135, I think?

Anyway, I've only done regular steel, not cast yet ... and my parts ShopSmith has a coupla cracked parts that need some love... is it doable with this hardware?

-- A
Click to expand...

Thank you all! I'll either find a friend of a friend to fix it, or toss the piece :D

-- A
 
yup...

Arc,Nickel rod,and lots of luck when cooling..thats the way to WELD cast iron..

We were taught in vocational school brazing is superior to welding cast iron for many reasons (that I wont list!)..I've successfully brazed the "ears" on a tranny where it bolts to the bellhousing that snapped off a 3 speed muncie tranny with oxyacetalyne..its not that hard to master brazing--its more like soldering than welding..they claim the brass goes into the pores of the cast iron and makes a strong union,in many cases stronger than a weld!..just "V" groove it,clean it good,use some borax on the brazing rod or buy coated ones,and fill it in!..

I always thought brass or brazing was weak,until my shop teacher brazed a 3/16" strip of steel about an inch long to a junk cars roof we used for training,(a 63 Falcon!)-and hooked it to a chain falls,and picked it up off the floor!..he then showed us a machine that tested welds by pulling metal strips apart with hydraulic pressure..it took over 3500 lbs of pull to snap the METAL,not the brazed area!!..I was pretty impressed..

I dont think nickel rod is any stronger,in fact I bet its not as strong--a friend nickel welded a leg on my cast iron wood stove for me,he's an expert welder,even welded a starter bolt area on a small block and had it hold,he's that good--and it snapped off a few days later,and it looked like a decent weld too. :eek1: .I brazed it back on after grinding the welded area off,and its yet to break--still holding 10 years later!.. ;) ..

I've seen guys braze cracked blocks to stop water jacket leaks too.. :eek1: not sure how long that would last,but it held as long as they drove the vehicle..a T-case adapter might be pushing it though--there is a lot of weight and tourque on it..only one way to find out!.. :wink1:
 
Exceptionally good idea with nickel rod to peen the weld bead as it cools. Use the point of your chipping hammer.
I did this with Rockmount "Jupiter" rod with a TIG welder on numerous blocks and heads. The only part that would not 'fix' and stay that way was an Iron Duke block. That was a fustrating day....
 
Pre-heat thoroughly, weld a little at a time with ni-rod and peen in between welds, then a very slow cool. That's the way we do it and i haven't had a crack yet, or any repairs come back. Typically I'll only weld about an inch or so at a time, then peen that and weld another inch.

A big bucket (or other sutitable container) filled with floor dry or sand helps let the part cool over a long enough period. Buried in floor dry the last part I did took 13 hours to cool to room temp.

Rene
 
Tig with Nickel filler rod works well too.
 
big83chevy4x4 said:
i have tried welding mild steel to cast with a MIG, it didn't hold. once i set it down with the weight on the weld, it broke off. it looks like i didn't even weld it to the cast, nothing on the cast at all, they were only spot welds.

i have to weld up my adapter and going to do it with nickel rod and my lincoln ac225, hopefully i have better results.
Click to expand...

Same happened to me with my Miller175.
 
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