Can Cast Iron be Welded

[hardtail]

radkins I'm curious if theres a quick and easy way to identify which casts are weldable? Those 2 machines I mentioned where built in the 30's and 40's and seemed to have better high quality castings, at least the scrap dealers until the price dive of late claim, I guess they were a bit more picky with what went into making it back then? I'm sure a lot of cast today is of high quality but it seems that a certain amount of questionable stuff has crept in when other countries jumped on the manufacturing bandwagon?

Stitching the crack was mentioned, this is a good solution if that style repair presents itself, Lock n Stitch has some good info on the changes CI undergoes when welding, of course their selling their product which is good but cast can be repaired by welding.

Ed this was a good question and I think radkins has explained it quite nicely, probably why the amateur looks at CI repair as voodoo.........LOL I guess the basic thing is to identify the cast, try and control the stress along the weld to a minimum while using the most suitable filler for the job?

I'll try and link an older fella that has done some remarkable repairs and really is his business for unobtainium parts nowadays, it would take a lot of patience to turn out this work. In particular look at his manifold repair.......

http://my.enom.com/14894/page99.htm

[radkins]

I have a broken casting on an olde Monarch lathe that is in need of repair. It's nothing serious or dangerous, but just something that I'd like fixed. If I ever have occasion to remove it, I'll see about getting it repaired, but until then, it will just have to wait.

Without seeing the part it would be hard to tell for sure but this does not sound like something that would be highly stressed so I seriously doubt it is a Malleable casting, in all probability it is the very commonly used Grey iron in one form or the other and should weld easily. Have you considered brazing this part? Brazing, when practical, is one of the easiest ways to weld cast iron and quite often will yield the strongest weld when properly done. A lot of people tend to think of brazing as more of just a "band-aid" approach but in fact on cast iron a properly done brazing job using the very common bronze filer rod, either bare with bulk flux or flux coated, will produce a joint that can actually exceed the base metal in tensile strength.

[rbregn]

If you weld cast with the"wrong" procedure, braze cast or even weld it with the correct procedure. If it is done good, it will break away from the weld as the weld is stronger then the original material. I understand the engineers thinking that using steel filler doesn't work, but I also know real world experiences that prove otherwise. I had a job at a job shop and we repaired anything that came in the door, if the customer was willing to pay the price. Our preferred method was brazing for maximum strength, but there was times we used cast "nickle" rod and there were also times when we used wire. Everything we did worked. I did things there that I didn't think would work, but the boss said to do a certain way and I was proved wrong. There was very few things that we did not try.

[rbregn]

We did things like the link above in Hardtails post

[radkins]

radkins I'm curious if theres a quick and easy way to identify which casts are weldable?


I'm sure a lot of cast today is of high quality but it seems that a certain amount of questionable stuff has crept in when other countries jumped on the manufacturing bandwagon?

There is a spark test similar to that used to tell steel from cast iron but it is a bit more involved and could be confusing trying to explain without pictures. There are a couple of good sites that go into detail about this and explain it quite well, I will see if I can find something and post a link.



You sure hit the nail on the head about that imported stuff! Chinese iron castings are "hit and miss" at best and can sometimes be completely different even on otherwise identical machines. I tried to weld a Chinese made vise for a fellow a couple of years ago and nothing I could do would even stick the parts together, I could not even braze it. With the imported iron you can expect to run into anything.

[radkins]

If you weld cast with the"wrong" procedure, braze cast or even weld it with the correct procedure. If it is done good, it will break away from the weld as the weld is stronger then the original material. I understand the engineers thinking that using steel filler doesn't work, but I also know real world experiences that prove otherwise. I had a job at a job shop and we repaired anything that came in the door, if the customer was willing to pay the price. Our preferred method was brazing for maximum strength, but there was times we used cast "nickle" rod and there were also times when we used wire. Everything we did worked. I did things there that I didn't think would work, but the boss said to do a certain way and I was proved wrong. There was very few things that we did not try.

This is where a lot of confusion gets started when someone manages to "stick" two pieces of cast iron together with steel and apparently produces a usable weld, the key here is usable. If a piece of cast iron is broken due to a blow or maybe to an unusual shock that will not be present after the repair then this type of "welding" may seem to work. For example a flange ("ear") for a bolt on a transmission bell housing I saw not long ago was welded on with stainless steel and the owner proudly pointed to his "success" at using the 308 stainless rod. But was it really a successful weld? The ear was broken off when they did not remove the bolt when removing the transmission so now that it (the transmission) is bolted back in place the load that broke the part is no longer there and that weld has little load on it. Quite often iron castings are broken due to misuse, abuse or some other form of temporary load that will not be there after the repair so that weld that seems so successful may hold little or nothing once the load is re-applied.

[torker]

I agree with a lot of the "Expert" points made here...however...where the heck are all the experts when I'm layin in the mud on a mountainside...trying to get the guys machine welded up so he can go back to work in the morning?
All this coming from guys who have worked in big shops with all the bells and whistles.
Guess what? There really is a real world out there where your ideas won't work...and there isn't always big heating ovens etc. out there.
There are MILLIONS of successful Ni-rod repairs done in the field every year.
I've seen a lot of weird looking repairs that shouldn't work...but they do.
I think the best point was the "suprise" load factor.
In some cases..you could prolly stick the break together with bubble gum because it may never see a load or force like that again.
You gotta use your head...look at how it broke...or why it broke.
90% of the time it was because bolts fell out or loosened or young Billy smashed into the cat with a skidder or whatever.
Russ (still making a living welding cast all wrong apparently)

[radkins]

I agree with a lot of the "Expert" points made here...however...where the heck are all the experts when I'm layin in the mud on a mountainside...trying to get the guys machine welded up so he can go back to work in the morning?
All this coming from guys who have worked in big shops with all the bells and whistles.
Guess what? There really is a real world out there where your ideas won't work...and there isn't always big heating ovens etc. out there.
There are MILLIONS of successful Ni-rod repairs done in the field every year.
I've seen a lot of weird looking repairs that shouldn't work...but they do.
I think the best point was the "suprise" load factor.
In some cases..you could prolly stick the break together with bubble gum because it may never see a load or force like that again.
You gotta use your head...look at how it broke...or why it broke.
90% of the time it was because bolts fell out or loosened or young Billy smashed into the cat with a skidder or whatever.
Russ (still making a living welding cast all wrong apparently)

You right there are millions of Ni-rod welds done successfully in the field, there is nothing "the wrong way" about that. As far as laying in the mud on a mountain side trying to get that machine up before morning I know from experience what you are talking about, that's exactly what I have been doing since 1969! My shop was my base of operations but about 90% of what we did was in the field at the mountaintop mine site, I am sure in conditions almost exactly like what you are doing (except probably a lot warmer where I was ). I have made a great many welds, on cast as well as about everything else, that did not conform to the proper procedure as far as preheat, post heat, etc since it simply was not practical under the conditions at the time of course you are obviously well aware of this. I did however try my best to do as much right as possible and since choice of filler rod/wire was not dependent on conditions I went by the book as much as possible, since excess warranty work would have destroyed me financially I could not afford to do otherwise. This thread was about welding cast iron and it kind of got way out in left field over a suggestion to use what is considered by all normally accepted welding practice to be an unacceptable method, welding cast iron with carbon steel rod/wire. The biggest problem with leaving something like this unchallenged is that a novice welder may be tempted to try it unless he hears both sides and he would be doing so without knowing what might happen. If it was just a case of "Oh well that didn't work let's try something else" it would not be all that bad but that is not how it is. The fact is if a novice, or anyone else, does attempt to repair an iron casting with the wrong filler then the damage will be compounded by a LOT! Since the weld bead along with all of the base casting that has been contaminated (diluted) by the steel must be removed in order to expose undamaged base metal before the proper filler can be used the part may then be ruined. Often on a small part or thin casting what started out as a crack that simply had to be beveled would then be a gaping hole by the time all the damaged metal is removed. Welding an iron casting is tricky at best but it can be done most of the time however each succeeding attempt gets progressively more difficult so it is very important to get as much as possible right the first time so there won't be a second time.


Torker, Some years ago the company I did most of my repair work for bought some large Euclid Rock trucks from a coal operation in Southern BC, I think the name of the outfit was Dominion Coal? At least I am thinking it was a coal operation, any chance you may have heard of it?

[Ed Tipton]

Torker... Your point is well taken. The owner/operator of a piece of equipment on a mountainside, presumably making the big bucks, could probably care less about "going by the book". All he knows is that his nuts are buried in the sand and it's getting hot, and all he's interested in at the moment is getting his equipment back on line.

Radkin...Your point is equally well taken. With something as difficult and "iffy" as welding cast iron, when you know the proper technique, and especially where there is liability involved, it is not only prudent but also professional to use the proper procedures and techniques to accomplish the repair, especially when and where conditions allow you to do so.

Both of you guys are equally correct...at least from a philosophical viewpoint. Far be it from me to find fault with either of you.
My original question has been answered, not only by the two of you, but collectively by everyone who took the time and effort to respond. Thanks to all.

[radkins]

Torker... Your point is well taken. The owner/operator of a piece of equipment on a mountainside, presumably making the big bucks, could probably care less about "going by the book". All he knows is that his nuts are buried in the sand and it's getting hot, and all he's interested in at the moment is getting his equipment back on line.

Radkin...Your point is equally well taken. With something as difficult and "iffy" as welding cast iron, when you know the proper technique, and especially where there is liability involved, it is not only prudent but also professional to use the proper procedures and techniques to accomplish the repair, especially when and where conditions allow you to do so.

Both of you guys are equally correct...at least from a philosophical viewpoint. Far be it from me to find fault with either of you.
My original question has been answered, not only by the two of you, but collectively by everyone who took the time and effort to respond. Thanks to all.

Sorry for going a little off course there but that was more than just fudging on the procedure because of conditions and in that case was a seriously flawed selection of materials that could lead to damaging the part instead of fixing it. I probably should have just let that go instead of ranting on about it but I have just seen so much of that sort of thing and I know from past experiences the problems it can lead to. Someone doing it because they simply did not know better, which was almost the case, is one thing but to recommend it to someone else in spite of the fact it is so contrary to all normally accepted welding practice is not even giving the repair a chance!