welding steel tabs onto ductile iron.

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I'm designing a parking brake system for a test machine.  It's in no way a prodction solution.I would like to take a Carlisle brake, which is a ductile Iron housing, cut it's mounting ears off and weld my own on.I've spoken with Carlisle engineering and they actually reccomended we try that (rather than make a new caliper from scratch to use their internals -which was my first idea.)I figured to just preheat the casting (no idea how much) and tig A36 or 1018 or whatever tabs on it with er70s2    ??? just a default guess.so my question is what process would be my best bet?  to keep down any warping.  because the piston needs to still fit into it when I'm done.thanks,
Reply:I don't know what ductile iron is, but give it a spark test.  If they are short,red  with no tails, then use cast rod. Otherwise I would mig it with S6.  Least heat.  Its a brake, I personally would be more comfortable with 7018 even though it may be hotter.  Is this sort of like a soft cast steel? DavidReal world weldin.  When I grow up I want to be a tig weldor.
Reply:Originally Posted by David RI don't know what ductile iron is, but give it a spark test.  If they are short,red  with no tails, then use cast rod. Otherwise I would mig it with S6.  Least heat.  Its a brake, I personally would be more comfortable with 7018 even though it may be hotter.  Is this sort of like a soft cast steel? David
Reply:OK, from somebody who knows ......   Ductile iron is oftentimes what people call "cast steel" .....    many tractor front axles, loader axles, Case backhoe booms, etc. are made of this stuff ....  Stamped right on it, "Ductile Iron ..  Do Not Weld"  ,,,,, hahahahahaha ....  go right to the dealer, you can buy new spindle ends to weld on ...... IF you preheat, and peen, and post-heat and slow-cool properly, you can weld ductile iron with regular 7018 rod.  ALSO, you can weld with nickel 55 or 99 rod .....  if you want to go with minimum heat, with the least likelihood of cracks, use the NI99, but it's also the most expensive ($50/ lb. or more).  It's also the least strong, but for a prototype it may be adequate for your purposes.
Reply:I would use nickel rod and pre heat based on thickness and peen as well as post heat. You may even want to get it up to temp and then leave the flame on a low setting to keep the heat in and prevent cracks. Nickel would be my call.'Mike
Reply:Okay, pun timeJust my two cents, use the nickel(Let the moaning begin)Seriously, though, Ni99 with GTAW, you don't necessarily have to preheat.I r 2 a perfessional
Reply:Hmmm, the heads and barrels on my old Harley are made of ductile iron and that's not cast steel. Cast steel can be welded to mild steel with no preheat, postheat or peening using 7018. Being as it is a prototype I'm not sure I wouldn't braze it. I have used brazing alloys that had 100,000 psi tensile strength. I've brazed up gearboxes and bearing housings on 640 pumping units (that translates to 640 tons per square inch in torque) and never had one fail yet. That's pretty tough.The difference between art and craft is the quality of the workmanship. I am an artist.
Reply:Originally Posted by Jolly RogerHmmm, the heads and barrels on my old Harley are made of ductile iron and that's not cast steel. Cast steel can be welded to mild steel with no preheat, postheat or peening using 7018. Being as it is a prototype I'm not sure I wouldn't braze it. I have used brazing alloys that had 100,000 psi tensile strength. I've brazed up gearboxes and bearing housings on 640 pumping units (that translates to 640 tons per square inch in torque) and never had one fail yet. That's pretty tough.
Reply:Preheat to 350º in a kitchen oven. then immediatly weld with stick nickel rod or TIG with 309 filler wire. Then bury the weldment in a bag of DRY sand overnight.Make sure you get full penetration, so if you need to put a bevel on the mating edges prepare it ahead of time.The cast metal expands and contracts a lot. That is why the nickel cast electrode will help to be more maleable, just as the 309 stainless filler wire with the TIG.TIG will have the lowest heat input and make expansion and contraction issues at lower levels than SMAW.7018 has a higher nickel content but the nickel cast electrode really is the right thing for the job. The 7018 might work but you will have the awnswer when you remove it from the sand.
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Reply:picturesthe carlisle brake has mounting ears straddling the disk.   my application has a rim far to small to allow that.so I modeled an equivalent housing with ears on the side of the barrel.  it was my origional intention to machine a housing and use the guts of the carlisle unit.It is a spring applied parking brake.  oil pressure opens it.  a bellville spring closes it.  (there is no panic stop) Attached Images
Reply:Ductile iron is oftentimes what people call "cast steel" - your statement, not mine. And it makes absolutely no sense because nowhere in your post do you clarify that it is in fact cast iron. Think about all of those who don't know the difference. I do know and won't even tell you what I was thinking about you after reading that.I am not a mind reader and can't read your thoughts only what you type. It took you a second post to try and say - ductile iron is sometimes what people mistakenly call "cast steel" but it is in fact cast iron. You never once used the words cast iron or clarified the difference. DUCTILE IRON IS CAST IRON. All caps so your poor reading comprehension skills can get what I was saying. Ductile iron can be welded to steel using 7018, using all of the steps you described and if you get really lucky it won't crack out, but nowhere is it a recommended procedure. I won't go into details but there are some really good reasons why nickel and bronze alloys are the recommended materials for joining cast iron (ductile iron) to mild steel (look up dissimilar metals) as well as for repairing broken iron castings (again ductile iron - not cast steel) for the very same reasons. I've done a bit of prototype work and recommended brazing because it doesn't require the really high dollar electrodes, time consuming preheating and postheating, nor peening, and if locations have to later be changed you simply heat it up and it falls off, no cutting or grinding required. The longer you take and the more money you spend on your prototype the longer it takes to recoup your prototyping costs. I have used cast iron tig rods that required no preheat, postheat or peening and they worked wonderfully. The easiest cast iron repair I have ever made. I have no idea what the rod was as it has been 8 years since I have used it, but I do know that it was incredibly expensive, gray in color, required pure argon and the boss only got one of them. I use Allstate CoreCast 8600 all the time for welding iron castings to mild steel with no preheat, no postheat and no peening. I didn't mention it because of the cost involved and it is gmaw. Over 40 bucks a pound and the smallest spools I have found are 10 pound. Not to mention the need for 98%Ar/2%O2 and a very healthy wire machine to burn it as it is spray transfer only.  Large steel castings, yes cast steel, not cast iron, are welded to mild steel using 7018 with no preheat, postheat or peening required. It is done on a daily basis in the oilfield. It is also used for repairing broken steel castings as well as building worn ones up for re-machining to tolerance, and we still don't preheat, postheat or peen them though we do put a shop heater to blowing on them after welding them up in the winter if it is below 60 degrees just for insurance. They are used for weld-on bearing housings on the same pumping units referred to in my earlier post as well as those larger and smaller and a whole lot of the connections used in all of that piping. In construction I have seen many cast steel connections welded to steel pipe using tig and ER70S2 for the root and hotpass and completed with 7018 and again no preheat, postheat or peening. It may be different up in Oregon due to the huge difference in temperatures from those we have in the south. I think we had 2 really light freezes last winter here in New Orleans. I have seen 7018 welds on mild steel crack back home in NM due to the ambient temperature being near 20 degrees with a 30 mph wind blowing. My boss sent me to figure out why everyones welds were cracking out and that was all I could come up with. I even tried 7024 with the same result. I went back the next day (Sunday) after it had warmed up to about 40 and tried it again and had no problems. By Monday it was up to 60 and nobody had any problems.Learn to communicate. Learn to say what you mean with the words that you use. Then us lesser mortals with poor reading comprehension skills and no extra sensory perception skills can understand what you are trying to say instead of thinking you have your head where the sun doesn't shine, and those who don't know the difference between the two materials will know once you are done. There are a lot of newbies here that don't know any better. On a side note I maxed reading comprehension twice on the ACT's and am reasonably sure it wasn't any problem of mine and though I don't like throwing it out there I am open to a battle of the brains but must warn you I come fully loaded. If it must be that I will most likely just ignore you. I would prefer we get along and share what we know in a way that others can understand. Things occasionally come out a little rougher than I intend at midnight after spending the day in 100 degree temps with 85% humidity and no wind or shade welding down inside a steel can. As soon as it gets here I will be trying out a Phase Change Cooling Vest and will definitely pass on to everyone if it works or not. You probably don't need those things up there, lol. I flew from El Paso, TX to  Seattle in October once, thought I was going to Missouri up until about an hour before the plane left (Army life ya know) and was told we wouldn't need coats. I thought I was going to freeze. I was there a week, never saw the sun and the only time it wasn't foggy was when it was raining.My apologies to those not involved in the pi$$ing contest.The difference between art and craft is the quality of the workmanship. I am an artist.
Reply:I looked it up in the bible.  Ductile iron is a type of cast iron, also known as nodular iron.  Can be welded, but needs post heat.  Recommended rod is nickel Has been successfully welded with 7018.   This is out of the book.  If you would like I can copy the two pages, no time now, I have to go to work and am Waay behind.DavidReal world weldin.  When I grow up I want to be a tig weldor.
Reply:There will most likely be a couple of raised bumps inside the cylinder when you're done. If so you may have to hone those down? If I recall those pistons are fairly flush in fit. At lest feel around in there just in case.
Reply:And of course ductile, like all groups, is manufactured with a fairly wide range or prpeis and characteristics.  All the way from pipe, which needs to be welded, to specials ripper shanks which should not be welded. "Should noty" means intially. It changes the property as well as voids any warranty. But once something is worn down beyond service duty or broken, then the "should not" becomes "here's how"..  I imagine this break cylinder is one of those items designed without welding in mind one way or the other.
Reply:"Ductile iron" is a type of cast iron.  Also known as "nodular iron".Cast iron is "cast iron" because it is iron with LOTS of carbon in it.  So much carbon is in the molten metal that the carbon can't stay in the structure of the iron crystals (at the molecular level) as they cool and instead it comes out of solution as small localized 'chunks/flakes/nodules/grains/whatever' of carbon and/or as various carbon-iron crystal structures (carbide structures).  Cast iron contains MORE carbon that steel does.  The carbon level in cast iron is greater than about 2.1%.The various 'other' alloying elements (element as in silicon, chromium, sulfur, lead, etc) and the processing (time/temperature/etc) of the cast iron make the different types of cast iron.  Like grey cast iron, white cast iron, ductile/nodular cast iron, malleable cast iron, etc, etc."Steel" is an -alloy- of iron and carbon (and sometimes other things as well).  The iron and carbon are in the same crystals (at the molecular level) as the molt steel cools.  The carbon level is "steel" is lower then about 2.1%."Wrought iron" has a very low carbon content (almost pure iron), but it has included in the physical structure of itself fibrous grains/strings of slag that have been beaten/forged/rolled or otherwise 'worked' (wrought is an older/archaic form of "to work") into itself.  Real wrought iron is pretty much no longer commercially produced, except for maybe some small-scale 'artisian' type producers.  Most 'wrought iron' today is actually just mild steel.For dsergison, braze your new mounting tabs on.  As long as you are not doing an aircraft or race vehicle or something heavy or fast or both whereby the brake will get red hot in use and thus melt the brazing filler, brazing should be fine.  Machine a flat where you want your new tabs to go, have a flat on the mating base of the tabs, braze together.
Reply:Sandy ive seen a lot of ductile pipe go in the ground for water main,, never welded. its bell and spigot or a mechanical joint, cut it with a friction blade..
Reply:Oh, another approach for prototyping would be to totally skip the weld/braze process for attaching the new mounting ears and just go with some mechanical mounting method instead.  Bolts, screws, split collar around the main cylindrical casting, whatever.It's a prototype, not a final production unit or attempted final production unit.
Reply:So I stand by earlier advice of nikel rod and pre and post head as needed.'Mike
Reply:Just thought I'd add a little to what MoonRise said. Two things determine the properties of cast iron; the rate of cooling, and the alloying elements besides the carbon. When plain cast iron cools quickly, essentially all the carbon remains combined as iron carbide, a very hard but brittle compound. Chills are placed around such items as locomotive wheels to give the hard, wear-resistant surfaces while the inside which cools slower will be the tougher grey cast iron. Many of the alloy cast irons behave similarly; when they cool slowly, the excess  carbon separates as flakes of graphite which gives the grey color.   If some elements such as magnesium and cerium are added in small amounts, they affect the way the carbon separates, producing instead anodular or spherical form rather than the flakes. The flakes act as small stress raisers and weaken the material whereas the spherical form does not. In fact, the ductile form can actually be bent without breaking. Cast iron has less shrinkage than average steel, but due to its brittle, (non-ductile) nature, it can't stretch when needed so cracks instead. Because its tensile strength is much less than steel, when holes are filled in cast iron parts using steel pieces, the steel is usually much thinner to allow it to stretch.When cast iron is heated by welding, it remelts and cools as the brittle white form unless the rate of cooling is very slow. Using high Nickle filler creates a high nickle alloy in the weld zone which shrinks less when it cools and this also puts a very ductile material next to the cast  iron, which is very ductile to allow for shrinkage which does occur. Brazing does not heat the iron enough to cause the transition to occur.Besides being a good material for casting (thin-flowing, small melting range, non-reacting wrt air, cheap), cast iron also absorbs vibrations so makes better machine bases, gear cases, etc. than steel would.  It can easily be melted in a backyard cupola, (neighbors and smog officials not withstanding).
Reply:Originally Posted by weldbeadSandy ive seen a lot of ductile pipe go in the ground for water main,, never welded. its bell and spigot or a mechanical joint, cut it with a friction blade..