Welding Cast Iron

hot glue would be a good analogy.:) it looks like you got the rod covered!
dependent on how thick of a section of CI you are repairing, would be the deciding factor in which tip to choose
start with the smaller tip and adjust the gas pressures to low settings like if you were silver soldering, unless you were going after large game.
not knowing your torches, i'd guess about 5 psi acetylene , 10-15 psi O2 and see how that treats you
brazing is surprisingly forgiving, if you mess up, heat the part back up and knock the brazing out, or knock the pieces apart again.
i have repaired CI in very cold weather, no worries
keep a bucket of sand or wood/or charcoal ashes handy, when your repairs are done, stick em in sand or ashes- you'll be ok
the ashes or sand allow the CI to cool slowly
i'm happy to share what i know.
i'm glad that you can put the knowledge to use :grin:
 
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Ulma Doctor said:
Brazing is the joining of metals with bronze bearing alloys.
the parent metal is not melted, just the brazing rod,
Click to expand...

This is partially incorrect. Brazing has nothing to do with the filler metal(but is commonly a bronze) but the temperature. American welding society says that any filler metal in a joint above 840* F but not melting base metal is brazing. Below 840 is soldering.

Technically what most individuals refer to "silver soldering" is actually silver brazing. These are a silver phosphorous copper alloy. Common is 5-15 percent silver but some less common is 55 percent or greater. This needs no flux on copper but does on dissimilar metals, steels, and such.

There are silver solders but you will see them melt in the 400-500 temp range and are called "silver bearing solders" to avoid confusion the afore mentioned misnamed silver soldered. 100 years of bastardization is hard to kill

There are also aluminum based brazing rods and other uncommonly seen alloys such as nickle.

Silicon bronze is a common tig rod without flux. Do to the shielding gas flux is not necessary on clean metals. Cast iron because of its make up is never clean and needs flux

Gas brazing rod is of lower quality in that the components don't have to be as pure as tig rod as there is no electrode to contaminate. Most of the time it has flux pre applied but buy it without as time and handling can knock it off. You need extra flux any how so buy bare rod and heat them dip the rod in the flux. Flux sealed in it tin never goes bad nor do bare rod.

As far as welding cast goes. Cast rod with cast flux is the best, the results are a weld that is indistinguishable from the parent weld. It's also hard and involves a flame table(or someone with a rosebud) to keep the part dull red in heat as you weld.

A bronze braze would be my choice for small and thin casting. Doesn't work as well on manifold.

Stitching is a good choice for cracked heads, blocks, and large castings. This that preheat and welding will distort(and likely crack).

Nickle arc welding is my last choice. It's one many make do to lack of skill,knowledge or tools of the other processes. I have magnafluxed many nickle welds and most have micro cracks parallel to the weld bead even when done by excellent welders and correct technique.

Many time this is still "good enough" and of no issue. Heck many blocks and heads are prone to cracking I. Certain spots (some models I have seen 95% cracked) and still don't leak or give issues.
 
Firebrick43 said:
This is partially incorrect. Brazing has nothing to do with the filler metal(but is commonly a bronze) but the temperature. American welding society says that any filler metal in a joint above 840* F but not melting base metal is brazing. Below 840 is soldering.

Technically what most individuals refer to "silver soldering" is actually silver brazing. These are a silver phosphorous copper alloy. Common is 5-15 percent silver but some less common is 55 percent or greater. This needs no flux on copper but does on dissimilar metals, steels, and such.

There are silver solders but you will see them melt in the 400-500 temp range and are called "silver bearing solders" to avoid confusion the afore mentioned misnamed silver soldered. 100 years of bastardization is hard to kill

There are also aluminum based brazing rods and other uncommonly seen alloys such as nickle.

Silicon bronze is a common tig rod without flux. Do to the shielding gas flux is not necessary on clean metals. Cast iron because of its make up is never clean and needs flux

Gas brazing rod is of lower quality in that the components don't have to be as pure as tig rod as there is no electrode to contaminate. Most of the time it has flux pre applied but buy it without as time and handling can knock it off. You need extra flux any how so buy bare rod and heat them dip the rod in the flux. Flux sealed in it tin never goes bad nor do bare rod.

As far as welding cast goes. Cast rod with cast flux is the best, the results are a weld that is indistinguishable from the parent weld. It's also hard and involves a flame table(or someone with a rosebud) to keep the part dull red in heat as you weld.

A bronze braze would be my choice for small and thin casting. Doesn't work as well on manifold.

Stitching is a good choice for cracked heads, blocks, and large castings. This that preheat and welding will distort(and likely crack).

Nickle arc welding is my last choice. It's one many make do to lack of skill,knowledge or tools of the other processes. I have magnafluxed many nickle welds and most have micro cracks parallel to the weld bead even when done by excellent welders and correct technique.

Many time this is still "good enough" and of no issue. Heck many blocks and heads are prone to cracking I. Certain spots (some models I have seen 95% cracked) and still don't leak or give issues.
Click to expand...
This is a very helpful explanation. I have copied it to study, along with most of the others because at my age, short-term memory is something that gets tested and sometimes fails.
Cheers,
Trim sends
 
I run CI like Firestopper said, with a twist.......Not saying this is any better but, I use Aluminum Bronze and AC to TIG braze CI with good results. AL or SI Bronze isn't all that expensive either.
 
This is an old link, but, if anyone is still interested; Ni-rod is the best, (in my opinion) for stick. However, 99%, 91%, etc, are super expensive. They are classified as machinable.
A less expensive alternative that I use ($8 per pound compared to $50 per pound) is Lincoln Ferroweld. Every company has their own version. Only draw-back is that they're not classed as machinable. (You need to use a grinder).
Still need to pre-heat, but I have had good results.

Jon.
 
In my other life befofe retirement I installed & repaired Large Air Compressors we used this method of repairing some cracked & broken casting. It works & many of the old machines are still running today.

http://www.metalcrackstitching.com/
 
I used expensive ni rod for welding a steel plate atop a cast iron harbor freight anvil.
 
I have also used a cast iron rod with a torch that is machinable and works quite well with preheat and a slow cool down in sand or kitty litter.
 
One-match fire said:
This is a very helpful explanation. I have copied it to study, along with most of the others because at my age, short-term memory is something that gets tested and sometimes fails.
Cheers,
Trim sends
Click to expand...

I have used sil-floss for copper to copper and it works well, BUT I know it will not be good for lets say copper to steel, what flux can be use to use sil-floss for dissimilar metals.
 
I've learned to not use a grinder to v the crack but use a carbide cutter to do it. the pre heat ard slow cool down are to me the most important. The thinner the piece is the more it needs the pre heat. just my two cents.
 
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