Various attempts to join cast iron to mild steel plate

[HT2-4956]

Another reason I like to start with a higher preheat than what you seem to think appropriate is that I can use a softer flame while brazing. If you're having to run your flame towards the top end of what a particular size tip will give you because the mass of the part is stealing heat a way to quickly the higher velocity of the flame tends to blow your puddle around.

But I do agree with you in that there is such a thing as trying to braze at to high of temperature. All though I'd have to say that the main indicator that you're getting things over heated is that you're starting to boil the zinc out and getting porosity in the puddle and not any thing to do with how the flux is acting. I have a tendency to work really hot and I often times find my self having to back off because I'm starting to over heat things to much.

[HT2-4956]

Weldordie,

Just so you don't think I'm making this stuff up as I go...

This is from the AWS handbook, Volume 2, 8th edition

[Denis G]

HT2,
BD1, Zap, Dennis, HT2, Opus
Here is one thought that maybe combines your ideas. The red line is a leg that supports the weight of the barrel. The black line is a bracket that the cast legs rest against. The white lines are screws that attach the cast legs to the real legs. The cast legs are just there for looks and no welding/brazing on them is involved. At this point I would prefer to just buy another set in the right shape and start over so I am spending less time on this.
Attachment 1556621

Your solution looks better than mine. At least the struts are hidden and someone can get a broom under there to sweep. Maybe you can bevel some pieces of steel pipe and nest them in the hollows of the ornamental legs. That way they would be hidden and provide bracing. The beveled end of the pipe would be welded to the round steel base.

[tapwelder]

About half the stuff I read on the net suggest slightly oxidizing flame for brazing cast iron. My linde oxy-acetylene 2nd ed. suggest moderately oxidizing flame. Got another book oxy acetylene welding and cutting by j.w. giachino 1942. Says slightly oxidizing flame.

[tapwelder]

.....

[Weldordie]

$40 for a carbide burr! Obviously NAPA is not the place to buy those things. As to there not lasting long well, of all the different materials I've used them on over the years I'd have to say that Cast Iron has been about the gentlest on them. My experience is that if you're just using it on cast iron it ought to last for years. I've currently got one that's several years old and it still cuts into cast iron like it's butter. I think the biggest reason that carbide burrs dull out and fail to cut efficiently is not so much the material they've been used on but rather the way the operator has tried to use them. You have to use a little gentle finesse so they don't bounce and chatter around.

The main reason for using a carbide burr for a cast iron prep instead of a grinding rock is because a carbide burr cleanly cuts metal a way where as a grinding rock has more of a rubbing it off action. That rubbing action tends to leave a layer of smeared carbon platelets on the surface which can interfere with the brazing filler forming a good solid state bond with the faying surfaces.

One old school technique for helping insure you'd get a good bond when brazing cast iron was that prior to brazing you'd take a highly oxidizing flame and sear the faying surfaces and wire brush them. This was all about burning a way as much of the carbon on the surface as possible prior to adding the bronze filler.

Sorry about the blurry photos but my digital camera is going south. This is the best picture I've currently got showing what I think is a braze done at a hot enough temperature. I realize you can't tell all that much from it.

I'd be happy to try another carbide bit, if you will suggest a source where I might obtain one or more that will hold their edges longer than for just two cast iron manifold repairs. When I purchased the bit at Napa the clerk (mistakenly) told me it had a lifetime warranty, which I later questioned. That is why I inspected the flutes after I used it on three repairs. If the clerk had not told me about the warranty, I would probably still be using it, not knowing of its chipped edges. BTW, I am an advocate for "finesse," so it was not operator error that was responsible for the wear on the bit.

I don't think I need worry about my repair of the exhaust manifold repair, since I used a grinding wheel to v out the cracks, because the manifold does not need to hold pressure (unless it is not properly drained, again) other than holding water and exhaust gases inside the engine.

[Weldordie]

HT-2,

I'm wondering how you arrived at your statement that my brazing looked way too cold, other than perhaps I did not bother to go back over the filler material to even out the surface. I wasn't interested in the appearance of the repair, as long as it was structurally sound.

When I read the paragraph in the handbook that you posted, relating to the brazing technique, it says that one should heat the metal, until the rod melts when applied to it in order to "butter or tin" the metal on the sides of the groove, then fill in the void with rod. This is my technique, exactly, so if done in this manner, I can't see how it can be "too cold." It seems to me that the correct heat is dictated by the rod, melting when the surface reaches the proper temperature, much like when "sweating/soldering" copper pipe... the pipe need be only hot enough to flow the solder, no more, no less.

BTW... the photo of your end result looks way too hot.

[HT2-4956]

The way I had the importance of not trying to braze weld to a ground surface demonstrated to me was this....back in the early 80s while in a 2 year welding program I had the instructor give me two small pieces of a broken up manhole cover, tell me to bevel them with a grinder and then braze weld them together. The joint was probably around 8" long. So I ground (with a rock) a bevel on them, lined them up, preheated and went to brazing. The bronze looked like it was wetting out to the faying surfaces just like it was suppose to and I ended up with what from all appearances was a good looking repair.

A couple hours latter after it had cooled it got destructively tested by being thrown down on the floor. Oh man, it popped right apart. One side came completely off (right at the faying surface) and putting the other piece in the vice and using a chisel against the braze and a few medium hammer blows pulled it off that piece. Pretty much a complete failure.

The instructor then had me take the same two pieces and do it again only this time he told me to take a carbide burr and take a skim cut over the faying surfaces before brazing it. This I did and while I was doing the brazing it looked to be wetting out and bonding just like it did the first time.

After cooling it got the same rough treatment. Not only did it survive several good slams against the floor but it also got several good blows with a hammer with out pulling apart at the interface between the cast and the bronze.

The big take a way lesson from that bit of hands on welder training that's stuck with me all these years is that, just because it looks like it's wetting out and making a good bond doesn't necessarily indicate that it actually is.

[Denis G]

The way I had the importance of not trying to braze weld to a ground surface demonstrated to me was this....back in the early 80s while in a 2 year welding program I had the instructor give me two small pieces of a broken up manhole cover, tell me to bevel them with a grinder and then braze weld them together. The joint was probably around 8" long. So I ground (with a rock) a bevel on them, lined them up, preheated and went to brazing. The bronze looked like it was wetting out to the faying surfaces just like it was suppose to and I ended up with what from all appearances was a good looking repair.

A couple hours latter after it had cooled it got destructively tested by being thrown down on the floor. Oh man, it popped right apart. One side came completely off (right at the faying surface) and putting the other piece in the vice and using a chisel against the braze and a few medium hammer blows pulled it off that piece. Pretty much a complete failure.

The instructor then had me take the same two pieces and do it again only this time he told me to take a carbide burr and take a skim cut over the faying surfaces before brazing it. This I did and while I was doing the brazing it looked to be wetting out and bonding just like it did the first time.

After cooling it got the same rough treatment. Not only did it survive several good slams against the floor but it also got several good blows with a hammer with out pulling apart at the interface between the cast and the bronze.

The big take a way lesson from that bit of hands on welder training that's stuck with me all these years is that, just because it looks like it's wetting out and making a good bond doesn't necessarily indicate that it actually is.

Were you using flux, flux coated rod, or no flux at all?

[HT2-4956]

Were you using flux, flux coated rod, or no flux at all?

IIRC, I was using bare rod and dipping it in a can of flux. Which exact alloy rod and flux combination I can't recall. I am positive though in the memory that I used the exact same thing for both attempts at it.

On a general note... It's been quite a few years since I've used any thing except Harris FC-15 (flux coated) brazing rod on cast iron. I've come to really like it and haven't had any problems with it that I can recall. There are situations how ever where I'll pre scrape some of it off before using it. If you're trying to fill a deep narrow groove on a thick section using it you can quickly end up with too much molten flux in the way.

[Weldordie]

The way I had the importance of not trying to braze weld to a ground surface demonstrated to me was this....back in the early 80s while in a 2 year welding program I had the instructor give me two small pieces of a broken up manhole cover, tell me to bevel them with a grinder and then braze weld them together. The joint was probably around 8" long. So I ground (with a rock) a bevel on them, lined them up, preheated and went to brazing. The bronze looked like it was wetting out to the faying surfaces just like it was suppose to and I ended up with what from all appearances was a good looking repair.

A couple hours latter after it had cooled it got destructively tested by being thrown down on the floor. Oh man, it popped right apart. One side came completely off (right at the faying surface) and putting the other piece in the vice and using a chisel against the braze and a few medium hammer blows pulled it off that piece. Pretty much a complete failure.

The instructor then had me take the same two pieces and do it again only this time he told me to take a carbide burr and take a skim cut over the faying surfaces before brazing it. This I did and while I was doing the brazing it looked to be wetting out and bonding just like it did the first time.

After cooling it got the same rough treatment. Not only did it survive several good slams against the floor but it also got several good blows with a hammer with out pulling apart at the interface between the cast and the bronze.

The big take a way lesson from that bit of hands on welder training that's stuck with me all these years is that, just because it looks like it's wetting out and making a good bond doesn't necessarily indicate that it actually is.

On the surface it looks like a good lesson that your instructor taught you. However, the test has some flaws. It would have been better had the test parameters included using two different pieces for the second trial demo, instead of using the original ones. It just might be that the heat into the first pieces altered the metal in such a way, as to more readily meld the brazing material for the second test. And, you might have been able to do a better braze on the second test, due to your practice on the first test. I'm not convinced that a smash test is valid, due to all of the possible variations involved, however, I'm eager to try the determine a difference between grinding wheel joint prep vs burr prep with, perhaps, a more scientific test. But, it will have to wait, until I can obtain a manhole cover.

Where do you obtain your carbide burrs?

[William McCormick]

Couple of other thoughts....

When you O/A torch braze with low fuming bronze don't do it to a grinder prepped faying surface. Grinders (and sanding discs) leave a layer of smeared carbon that interferes with getting a good bond. Use a carbide burr for your prep. Nothing wrong with using a grinder to remove a lot of metal just be sure and go back over it with a carbide burr and take a skim cut on it to remove the "smeared" layer from grinding.

Another nice thing about torch brazing it with bronze is that the solidification doesn't pull things out of alignment like metal from arc welding does. And that can really be helpful when it come to keeping everything lined up like you want it.

I'd also have to give some thought to talking the customer into just going with 3 legs instead of 4. Besides insuring it'll take any "rocking" out of it on uneven surfaces it'll cut down on the amount of time it'll take to do it.

I think that any heat is going to warp the mild steel plate some.

Sincerely,

William McCormick

[William McCormick]

Five hundred degrees over time, will burn off carbon, that is what powder coaters do. After they are done the carbon is burnt off and the powder sticks.

When I TIG weld with Everdure I melt both base metals, which can take perhaps a minute or more to reach temperature before I start to add wire or move. But then it is just like welding mild steel. You just carry the heat with you as you go. I am basically adding in a lot of copper to the weld, which makes a new tenacious alloy.

I do not get such a copper looking weld as I see you guys get, however I do get a golden tint to the weld. You can tell there is some copper in the weld. You cannot file the weld, it is hard.

I weld vises together with it and they break at a new location or just never break again. We were misusing a vise a very nice vise one day, to hold a part very tight, I used a raw hide mallet to tighten the vise, and then beat on the part. My vise broke. So I Everdured it back together, and the fellow who was with me was laughing at me for even attempting it. But when it had cooled down and we did the exact same thing to it and it did not break he was just stuck there looking at it. He was looking at the marking on the welding rod, and trying to figure out what it was. You gotta go hot with it though. The puddle gets hungry for it.

Sincerely,

William McCormick

[HT2-4956]

About half the stuff I read on the net suggest slightly oxidizing flame for brazing cast iron. My linde oxy-acetylene 2nd ed. suggest moderately oxidizing flame. Got another book oxy acetylene welding and cutting by j.w. giachino 1942. Says slightly oxidizing flame.

tap,

Now that this thread has got me re-reading up on this subject I've come across some references to doing it (Braze Welding) with a slightly oxidizing flame also. The one thing I haven't come across is any discussion of the "why" you'd want a slightly oxidizing flame.

All these years I've been operating under the impression that a neutral flame was the one you wanted when braze welding. While I know from experience that it works well with a neutral flame (that's all I've ever done it with over the past 40 years) I'm starting to think I might have missed some thing important.

Next time I've got to braze weld something I'll for sure be trying a slightly oxidizing flame. It being hotter than a neutral flame I'm thinking it should let you keep a little more stand off between between the tip of the inner flame cone and the surface of the puddle.

One thing I'll say as far as technique goes is that... if you're having to constantly keep the tip of your inner cone right on your puddle to keep it fluid and moving where you want it then you really don't have enough heat (over all) in the part yet.

[HT2-4956]

No good way to clamp and hold the part back in place so I used the broke surfaces to "self" align it with one hand and used the other to put a good sized mig tack on it. After putting one layer of braze in the partial groove you can see in this picture (done right after mig tacking it) I ground off that mig tack and finished prepping a groove (with a carbide burr) all around the rest of the joint on both sides.







Not sure just what happened to break it off to start with but am pretty confident that if the same thing happens again it'll fail some where else in the casting and not at the bond between the braze and the cast.

[jackdawg]

Personally I would have just bolted some mild steel to the legs that I would weld then to the frame. Or perhaps for the right look, I might have tried riveting.

[psacustomcreations]

On Tuesday I spoke to my co-worker/the customer about this situation and even showed him this thread.

He had no problem with what happened and appreciated the honesty. I had been up front with him even before I started that I did not think this would work. I ended up paying him for the cost of these legs. He has another set of legs he will use on his project


As stated earlier, I ordered a bunch of Blue Demon NI55 and NI99 TIG rods in one pound packages from Amazon. These all came in Tuesday and Wednesday. I ended up waking up early this morning so I could work on the last ear.

The settings were:
150 amps DC+
Size 7 cup
1/8" tungsten
20 cfh argon
1/16" NI55 tig rod

I changed this ear up a bit and cut off part of the rounded surface so it would sit flat and I could weld on both sides. I initially cleaned everything with the grinder then went back and used a burr to skim over all surfaces.

While I was doing that and the rest of the following, I preheated a large bowl of sand in the oven to 400 degrees.

I preheated the pieces to approximately 500 degrees. I ended up having to use the propane torch since the acetylene fitting on the hose of my OA rig started leaking. The biggest problem I was running into is the 3/4" thick table was acting as a heat sink so it took a good 15 minutes to get up to heat.



Once it was ready I ran three passes trying to wrap the corners and keep going as suggested. My technique still needs work and practice.

I carried it inside and it went into the bowl of hot sand. I turned off the oven and let it cool today when I went to work.

The wife wasn't real happy waking up to find I was baking a bowl of sand at 5 AM in her two week old new stainless steel gas oven, but we have been together for 30 years so she is used to strange stuff.



I wired brushed everything this evening and found there was some obvious porosity in some of the welds.

[psacustomcreations]

I cut the piece in half and polished up and etched the weld. There was a bubble of porosity in the cut so that should mean there is more present in other parts of the piece.



I then did some destructive testing with the 8 pound hammer again. I tried to use the same force and technique as before.

There was an obvious improvement in this welding technique. I let the hammer hit the first piece twice from about 8 inches up and it did not do anything. I hit the piece progressively harder until on the 5th hit the cast piece broke above the weld. At that point I was hitting it pretty dang hard.

I grabbed the other half of the ear and hit it in the opposite direction. The flat bar was a little bit shorter on this section so it was a bit harder to hold it in the vise. Ultimately, the flat bar ended up bending on the 6th hit as I kept hitting the cast ear. I was not able to hold it so I flipped the piece around and hit it a few more times until it broke at the cast portion above the weld.




The short answer for me is that even with my crappy welding technique, this rod and the pre and post heat made a great difference to me in the strength of the product.

[farmer37]

You are trying to do the impossible.Wonder why this got 66 replies.

[psacustomcreations]

Thanks to Manokai, HT2, Weldordie, WNY, Storeman and others for the advice on rod selection and technique.

If anyone reading this has suggestions on the settings I used or new material to use like William McCormick, go ahead and post it.

I did a lot of searches on here and other sites to find out what rods, techniques and settings to use. If any of the pros or "hobbyists" have time to do a direct comparison of techniques like this it might help. Typically there is a thread on how a person did one repair but maybe my searching isn't as good as needed.

[psacustomcreations]

You are trying to do the impossible.Wonder why this got 66 replies.

You are probably right, no one has ever tried to weld cast to mild before. If I could just figure this out, I will be a millionaire.

[a2lute]

I got a nice cast iron bench vise with 1 mounting tab broken off for free. I made a tab out of some cold roll, Preheated both pieces, peened the weld as it cooled down from orange to dull red, quickly wrapped it up in an old asbestos blanket and tossed it in a bucket of kitty litter and buried it. This method will keep you out of the wife's stove, and I bang on this vise fairly regularly, it has held up well.

[ManoKai]

@ psacustomcreations - way to dissect the problem, consider alternate approaches, and close on an effective solution. Your revised technique of TIG welding with Ni-55 is solid. You learned as much with your earlier attempts as you did with your ultimate solution, IMPO.

You got this bro. Nice job!

[psacustomcreations]

@ psacustomcreations - way to dissect the problem, consider alternate approaches, and close on an effective solution. Your revised technique of TIG welding with Ni-55 is solid. You learned as much with your earlier attempts as you did with your ultimate solution, IMPO.

You got this bro. Nice job!

Thanks. Just trying to learn now and maybe help someone else that may need to do work like this in the future.

As much as I want to do this test again with larger pieces, I don't have enough time right now to give it a shot

[69sa200]

That's the nature of the beast. Cast Iron is strong but brittle. Any impact or side load to the weld or bolts will have the same outcome. Can you make them out of steel. Maybe a blacksmith can make some out of 1" twisted square steel and hammer out the feet. Or you can make them out of 1/2" round bar in a U-shape with 2 u-shaped legs welded together at 90 degree angle and bend out the U part at the bottom for the base. Not as nice looking but much stronger.

You could also make a loop of 3/4" round bar larger diameter than the top and connect it to the top with 3/4" spoke legs. 6 of them would hold that barrel but that's a judgment call. I was thinking of the step stools at the carnival the the elephants would stand on looked like what I'm describing.