ductile iron

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Got the pleasure of wotking on a 580  Case backhoe today  was wondering      On the boom and swing arm  it reads (ductile iron do not weld)  anybody have  any idea whyit cant be welded     and  what is ductile ironplease keep it simple kinda slow  thanks everyone hypertherm powermax 900 : miller 30a spoolgun ranger 305g lincoln ln-25more tools than a tool truck
Reply:Ductile is one of the cast irons. Of course as with most of the cast irons, welding can have damagine effects. And they don't mean that if it is broken 'don't weld on it' because at that point there are few choices. It isn't unusual to see little doodads welded on them either, as long as you keep the heat and the haz minimal. What they really mean, especially on newer machines, is that if you weld on it good bye warranty.
Reply:I heard that term before! But, I had to refer back to the text...There are 5 basic types of cast iron.1. Gray2. White3. Malleable4. Ductile5. Special alloyJust a review, cast iron is used in frames, large equipment and tools, it has very good damping capability and compressive strength and is resistant to wear, it is easily machined and castable, as the name implies. Ductile cast iron is also known as nodular cast iron because of the shape of graphite particles forming round spheres or 'nodules'. These nodules are precipitated directly from liquid iron by treatment with magnesium. As implied by the name, this form of cast iron has great ductility, with comparable strength to that of malleable cast iron. As prices have become more competitive, many times it now replaces gray cast iron.Weight:------------------------------------.25 - .27 lbs./cubic inchTensile strength:-----------------------60,000 - 120, 000 psiCompressive strength:---------------120,000 - 300,000psiImpact strength V- notch charpy:-2 - 30 ft./lbs.Hardness BHN:--------------------------140 - 330Modulus of elasticity:------------------18 - 25 X 10(to the 6th)   psiCoefficient of thermal expansion per degree Farenheit:----6 - 10 X 10(to the negative 6th)City of L.A. Structural; Manual & Semi-Automatic;"Surely there is a mine for silver, and a place where gold is refined. Iron is taken from the earth, and copper is smelted from ore."Job 28:1,2Lincoln, Miller, Victor & ISV BibleDanny
Reply:great question !    good answers.   nice job.       daye
Reply:Rookiewelder -I've been watching for this ever since I first saw a JI Case "do not weld" dipper stick.I've been secretly hoping to get a bargain on one with a broken boom; and then just find out exactly if the Ductile Iron (DI) can be welded or not.Do you have a broken stick; or just wondering about ductile?Today I had a chance to leaf through my copy of  "Ductile Iron", it has a chapter on welding, I gave that a quick review. Mainly it's the characteristic of having distinct layers that makes  DI welding difficult.I was surprised to find that brazing was strongly discouraged; mostly because of difficulty in removing spheroids prior to brazing.To make a long story short - Most recommended process without full annealing, is to use 50-60% Ni electrode, with a soft mildly penetrating arc. If anyone wants details about DI, I'd be glad to report the book's  hieroglyphics.Most notable: Under-bead cracking can be reduced by alloying with columbian (Cb), -without a capital c. Whatever that means! Maybe it's a line to trip-up copyright violators! Good LuckLast edited by denrep; 09-19-2008 at 12:51 PM.
Reply:As said, ductile iron is a form/type of cast iron.It is called ductile iron, because it isn't quite as brittle as and doesn't crack as quite as easily as 'regular' cast iron.http://en.wikipedia.org/wiki/Ductile_ironBut it is still cast iron, and is not a steel.Denrep,I think the element you/they meant is "columbium" aka niobium.  Which is sometimes used as a carbide controlling alloying element.  The best laid schemes ... Gang oft agley ...
Reply:You're right Moonrise.  I looked again, I read it wrong. The author was speaking of alloying the melt with columbium, for ease of future welding.
Reply:Thanks for the info everyone  nothing broken  just in the shop for pre-winter overhaul   wondered about  that ductile thing many times    this seemed to be a good place to askthanks again everyone  Denrep I will keep an eye out for one with a broken boom hypertherm powermax 900 : miller 30a spoolgun ranger 305g lincoln ln-25more tools than a tool truck
Reply:Originally Posted by denrepI've been secretly hoping to get a bargain on one with a broken boom; and then just find out exactly if the Ductile Iron (DI) can be welded or not.
Reply:So how can it be welded?
Reply:http://www.ductile.org/didata/Section8/8intro.htmEd Conleyhttp://www.screamingbroccoli.com/MM252MM211 (Sold)Passport Plus & Spool gunLincoln SP135 Plus- (Gone to a good home)Klutch 120v Plasma cutterSO 2020 benderBeer in the fridge
Reply:I worked for a large general contractor that bought some of those machines used in the late 90's. When the shop clean-up guy pressure washed one of them, he blew off the bondo that some one had "repaired" the stick with. I used some Certainium rods for the repair, back-step and keep as cold as you can-that was what Certainium called for. I have no idea what make-up the rods where because they use model numbers and dont want you to know you could get the same alloy for half price.
Reply:I see this one was brought back up.Problem is, the walls on the Case boom are relatively thin;  less than one inch if I recall.First time, gouged it all out, preheated, then welded.  Weld, peen, reheat.  Short welds each time, but never let it cool off.   Problem is, as you get to the end, the expansion from the heat is sufficient to put pressure on, and crack, everything you welded before, as you start getting to the end of the crack.Second time,,,   gouged everything back out again, no preheat, welded one inch.   Peened it, let it cool.   Weld another inch, peen and cool.   etc. etc.   As I recall,,,,   approximately a 6" crack.Took a day to do this,,,,,  had other things to do for the same customer, just kept coming back to this every time it cooled off.   End result,,,,   the customer used this for a few months, never cracked, then sold it.   This wasn't his daily driver, he bought it at a good discount, because of the broke boom.   Sold it for a considerable profit.I can't recall right now, if I ended up welding it with 7018, or Ni45,,,,  either will work.When I do the front axles (solid section, approx 2" thick, cut the ends off, vee them, tack, preheat, weld/peen/reheat ,,,,  unless it gets too hot, I don't stop.Last edited by mark8310; 07-28-2009 at 02:46 PM.Reason: added "no preheat"
Reply:I read on here that tig welding ductile iron with 309 ss filler wire would work when welding mild steel to ductiile iron. This is due to the high nickel content. Would it be better to weld stainless steel bar rather than mild steel bar to the DI again using 309 filler wire?Last edited by Alank; 07-28-2009 at 03:24 PM.
Reply:Originally Posted by Broccoli1http://www.ductile.org/didata/Section8/8intro.htm