Can You Weld Cast Iron??

[Music] don't turn on that light greetings father can you bend this wet noodle for me i don't know let me take a look yeah we can maybe do that we'll have to give it a try but you know what i think you're getting old enough to do this kind of stuff on your own your puny human brain cannot comprehend the strength i possess yeah i know buddy but what do you say we start off with a small bender at the end of the bench all right you remember how this works open up the bender first have enough space to get that noodle in there perfect let's cinch up that clamp just a bit not too much looks good now let's see if we can't find that handle take a look under the bench i think it's somewhere in that pile of old shoes okay you ready get a good footing go ahead and pull her around nice and steady well my cheap bender broke again those of you really good at taking notes may recall i have a love-hate relationship with this thing mostly hate if i'm being honest but i have it it's here and it gets used in fact i only realize just how much it gets used when it's broken joni mitchell was right all along despite the overly dramaticized intro some of which was true mind you this thing broke about a month ago if not more the part that keeps breaking is cast iron which means it's a pain in the butt to fix hence the feet dragging but it's got to get done i've got some time right now and as the old saying goes carpet dime i do have a second more bigger bender opposite this small one on this end of the bench for reference we usually youtube at the other end of the bench in case anyone has lost their bearing which is actually right this is a homemade clone of a hospital number two and it's way better than this import piece of junk but i don't have the tooling for this to make sharp crisp bends in small parts which is what this one is good at ipso factoid why i still have it wow we can't be more than what three minutes 24 seconds in i've already dropped two french words i didn't realize this video would be so high brow that's not a lot to work with is it so welding cast iron this gets hairy but between me and you it's not all that difficult there's really only one cardinal rule know what you're doing which unfortunately puts me at a disadvantage right out of the gate however and historically speaking i have a pretty good success rate and i'm happy to share what i think i know problem number one and coincidentally also the reason i'm still at large it can be difficult to identify can you tell by looking at it that it is indeed cast iron and not say cast steel or cast aluminum can you look at that and tell me definitively that it's not oreo cookie well it's not cast aluminum because it isn't i'm not trying to be a smarty pants but cast aluminum is completely different similar crumbly grain structure maybe but lighter and a brighter color the more you do this the more you recognize the usual materials i know that doesn't help much but aluminum is different than iron the only reason i bring this up is scare mongering i'm also pretty sure it's not oreo cookie though given its provenance you never know but in the famous words of carl's jr any sufficiently aged oreo cookie is indistinguishable from cast iron however the cast iron verse cast steel debate is a little trickier there are gray areas but here we can turn to the trusty spark test cast iron usually throws short orange sparks cast steel will make longer brighter sparks if you're still not sure you can try drilling it if you can cast iron chips will be flakier or powdery and cast steel will give you continuous chips the kind of chips you might expect from steel okay so we definitely have cast iron but the scaremongering doesn't end there did you know americans have over four different words for cast iron isn't that crazy and you know why because there are four to five different types six even if you believe the rumors we're now pretty sure that it's cast iron but is it gray cast iron or white cast iron is it nodular or malleable iron if you're looking to me for answers you're out of luck i have no idea i'm guessing it's regular cast iron because where this came from and what i paid for it but if it were say white cast iron which fun fact you wouldn't use to make a bender it'd be unweldable you'd weld it it'd break immediately explode maybe i don't know moral of point number one just like when you're welding anything it's best to know exactly what you're dealing with if it's really critical like you're welding your best friend's iron lung your only real option is to send it to a lab for chemical analysis but you're watching youtube here let's not get carried away so right out of the gate you've got at best maybe a 25 chance you're looking at weldable cast iron less than that if you thought it might have been cast aluminum let's stack one more thing against this shall we thermal expansion i know that might sound like a big word but don't worry it's actually two big words really close together cast iron is brittle and it has a lot of carbon in it like an imperial boatload in fact now i'm wondering is it brittle because of all that carbon in it i don't know what do i know do i look like a carbon based life warmth moral the story it has a lot more carbon than the steels you might usually weld and way more than aluminum when you heat it while you weld it when you cook it at those high temperatures in a small area the carbon in the cast iron will migrate to that heat zone like little children falling into a campfire that extra carbon turns the cast iron near your welds into a more different cast iron and you guessed it even more brittler so now when your weld puddle starts cooling down as it contracts it starts pulling on that brittle cast iron from every direction and what happens when you put stress on brittle cast iron you guessed it you've just been fired hey you know what let's try it i've never actually done this before not intentionally at any rate so this could go either way here are two little pieces of cast iron i cut out of my neighbor's engine block just for a minute let's not know any better and just weld it the way we normally would and just see what happens not exactly sure how to do this maybe end to end long ways oh look at that it's a nice little book match there maybe we'll try it and end this way i'm going to tig weld this just regular vanilla tig wire but we could do the same thing with stick or mig or whatever you usually use to weld in fact what i think i'll do maybe weld these ends to the bench put the main weld there and we'll leave the camera on while it cools down see what if anything happens i think if i weld them to the bench they'll act like a bigger piece of cast iron i don't know let's give it a try all right i did hear it crackle i didn't get the camera moved around and set up in time but we're just going to let it cool down like this yeah it's still pretty toasty i don't really see a crack anywhere though let's let it come down to room temp i assume this bench is gonna bring it down pretty fast all right it's been about five minutes ten minutes it's more or less cooled down it's a smidge warmer i heard it do that little dinging crack sound but i'm not really seeing anything oh i think i can hear it though oh it broke on this end i've got you around the other side of the bench now this is hard to see by eye but under good magnification you can see the entire weld separated from the cast iron and i think i'm even seeing cracks down the middle of that weld bead if i can lift this off the other two welds seem to be on there pretty good so i guess what happened because of the sort of geometry of this thing when these welds cooled and they contracted that weld bead gave way actually the brittle material at the border of the weld bead and also brittle weld failure on this side granted i picked that up a bit but you can see that cracked right through the weld bead weld in the middle is still there i don't know if i said the heat affected zone already but here you can really see it the zone affected by the heat the cast iron in this area is probably not the same cast iron we started off with chemically speaking i don't know if i can nope not by hand anyway i don't know what that looked like on video but that didn't really take too much effort again brittle failure right next to the welt [Applause] [Music] [Applause] [Music] [Applause] [Music] i made a new piece there just isn't enough to work with here anymore yes i could have machined a whole new plate and yes i could have probably just drilled two more holes up higher and mounted the vise about there but hey hey focus we're talking about welding cast iron here [Applause] so to weld this we've basically got two things to worry about assuming you're sure it's weldable cast iron on the one hand we have the high carbon content that could make things brittle and still on the same hand the cooling and contracting weld beads inducing stress i think those two things are actually intimately connected but for the purposes of this video we'll talk about them like two separate things and i'll just cut to the chase for the high carbon content and that whole potentially changing our chemistry thing the issue is essentially the highly concentrated heat we'll be using for welding i mean that's the definition of welding right that pinpoint heat is what draws the carbon in and mixes up all the magic lego blocks inside to mitigate that we should be very careful controlling the heat into the part what that means in practical terms is preheating and then controlling how fast or slow rather the part cools down there are some things you can do during welding too but hold your horses there cowboy we want to get this to four or 500 degrees fahrenheit that's around 300 c i think the exact temperature depends on the kind of iron we have but we don't know that now do we ideally you'd want to heat the whole piece up slowly and uniformly this isn't too bad because it's not a big part i could throw this in the heat treat oven or even in the barbecue but for this video and maybe for bigger parts you'll likely use a torch i've got a temple stick ready temp stick whatever these things are called temperature indicating crayon they're temperature sensitive crayons the mark will melt when it reaches the temperature it's rated for i'm starting a little low and then i'll move up to the next crayon i tend to usually overshoot my temperatures while future me heats the parts up over there let's talk about the bead contraction thing we said filler metal will contract as it cools and consequently put a bunch of stress on the parts that we're welding wouldn't it be great if there were a filler metal that didn't contract as much these are nickel alloy welding electrodes and you'll never believe this but they contract less than mild steel filler i know what are the odds right do you know why they call these nickel rods because you're going to need a lot of nickels to buy them depending which ones you get i believe these are 90 plus nickel turns out it's a lot easier for me to jump in the car and buy nickel electrodes for stick welding than it is for me to buy nickel rods for tig two things of note first i'm demonstrating how not to remove flux from cast iron electrodes i'm pounding them from the top against my bench you'll want to do it the correct way and pound them from the bottom second i think i'm doing myself a bit of a disservice by removing this flux a smarter person would just use these as they're meant to be used and stick weld the parts the flux is very important it's got vitamins and minerals or whatever to help the chemistry go right during the weld personally i prefer to live dangerously in tig weld it's unreasonable i know i know but i like to see exactly what's going on if there's something really gnarly in that casting if it starts to bubble and spit with tig i'll see it i don't know if i'll be able to do anything about it but i'd see it with stick welding it's just a big loud mess of smoke and fire and it's over having said that all of my initial cast iron tig welds broke and all the stick welded ones did fine so the parts are hot up to temperature and they're up in the air so the bench doesn't suck the heat out this part is relatively thick and the weld is short so it's not super important but generally speaking with cast iron you want to stitch or skip weld try to avoid one long continuous weld remember we're trying to manage heat input into the part in fact watching this now i should have probably pulse welded it tig isn't a great choice of all the welding processes tig is probably the hottest most focused arc you get but anyway do short welds and jump around some people seem to think that's to distribute the stress i'm not sure seems improbable you'd have any idea what stresses are developing in the part while you weld but it probably does more to control the heat input either way jump around jump up jump up and get down everything else is as normal might have been smarter to use a larger gas lens but keep as good as gas coverage as possible no drafts both for the gas and to avoid temperature swings on the part once you start see it through don't do what i'm doing and stop to reposition the camera and try not to stay in one spot don't overheat or cook anything if the cast iron gets red that's bad you just want enough amps to keep the filler moving though nickel rods are a little weird compared to mild steel in some spots it wets out some it doesn't depends on the heat depends on the casting just take it easy and consistent welding is finished but we're not done yet this whole thing is extremely hot and i'm going to put it in my heat treat oven to cool it down the oven is very well insulated i even preheated it just a little bit if you don't have an oven or your part is too big for your oven you can cover it with something something not flammable or bury it in the bucket of nice dry sand perhaps you have a fireplace stuff it in the ashes anything you can do to get your part to cool down very slowly and that's all we can do for today see you folks wow that's a lot uglier than i remember it looking the two pieces are still stuck together i'm no award-winning metallurgist but as welding goes it's probably a good first sign i don't see any cracks a little bit of digging on either side of the weld bead i've always found that hard not to do with cast iron but i did go a little over the top literally speaking maybe with that filler i don't know we'll see how it looks once it's before that however i'd be remiss if i miss a second time let's talk about peening if you get into welding cast iron sooner or later peening will come up like the name says peening involves well painting your weld it's meant to reduce the stress in your new welds and hopefully keep them from cracking you do this when your welds are still hot of course not the next day this is just a dramatic reenactment you'd want to do it firmly and consistently don't go ape poop on the part you just fixed right out of the gate let me just say i'm not quite sure how i feel about painting like this manual painting your welds not industrial style shot painting but i'm not a welder i don't do this every day the only time i really peen cast iron welds are when they're thin feels to me like you have less margin forever there as you weld you're losing heat a lot faster than you are with maybe something thicker like this but even then honestly it's a pascal's wager sort of a thing why not you know what i mean what's it going to cost you the premise i believe with peening is that the small upsets you put in the weld bead with the hammer force it to stretch you're physically mechanically deforming the bead think of it like auto body work maybe where you stretch metal panels with a hammer it tries to balance the shrinking caused by the cooling weld bead with sort of that forced expansion from the peening anyway i didn't peen this welt let's clean it up and see how it works shall we okay uh not great but not bad i don't think i don't see any serious porosity in the actual weld bead this was that undercutting i don't even know what you call it it's not really undercutting it's sort of maybe it is when you weld cast in my experience when you get to the edges the edge sometimes sort of burns back a little bit on the surface and if the weld bead doesn't wet out you'll get this little crevice kind of a thing in my younger days i used to really sweat that and i would try to weld it again sort of fill it but i end up just chasing it up the part though interestingly it looks like it tied in better to the good cast iron this is good cast iron and this is unknown import cast iron so maybe that's got something to do with the impurities or i don't know what i know maybe it's me looks like it wet in better on the bad cast iron here that it did on the good so yeah i guess it was me frankly not too concerned with how it looks i'm sort of happy with that wise but the proof is in the bending let's start out easy this is some quarter inch mild steel round there we go i don't know what that is but looks perfect see what else i got it's a little scary this is half inch stainless end up breaking something else here all right that was easier than i expected let's find something a little more serious here's some one inch mild steel hot rolled [Music] here goes nothing i might have to call my kid in for this one you know what let's try see if a little wd-40 doesn't help there we go so that's as far as i could pull it around i was running into my tripod but i think you get the idea maybe not the prettiest but that cast iron weld should hold up nicely at least until something else breaks that's all i've got hope you enjoyed and thanks for watching

Channel: This Old Tony

Views: 415,843

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Id: usRMtTFKpmI

Length: 23min 10sec (1390 seconds)

Published: Fri Feb 04 2022

Reddit Comments

[u/lts_talk_about_it_eh]

What I love about Tony's videos, is most of the time he's learning something new along with the viewers. Like, I loved what I learned about welding cast iron in this, but I also loved seeing him learn as well and while the finished product wasn't perfect - it worked for what he needed, and he can fix it better next time.

[u/ikidd]

I've migged preheated cast and then buried it in hot sand, peening it as it cooled. Seemed to work.

I'd probably try using an induction cooktop to keep a smaller part hot and slowly turn it down. Been using the induction hotplate for heating bearings a lot the last couple weeks.

[u/skibbin]

Tony is such a delight. So good at explaining, jokes are inventive without getting in the way