stellite

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we are welding a gate valve that has a seat dia of 10in down 24in tru a 8in bore with stellite.we can not stop it from cracking.any idea how to stop from cracking?thanks
Reply:What is stellite?  Are you preheating it?  Usually preheating before welding and wrapping with insulation to bake out and slowly cool usually helps.  Sounds like it's cooling too fast.
Reply:Why in the world are you using Stallite for "filler"??Stallite is used for stuff that needs wearability..We used to use it in "flutes" that are like a big corkscrew that sucked plastic pelletts out of a vat and into injection moulding machines..I have never used it as a filler because of the problems your having..What is the base material that your attempting to weld made out of??...zap!I am not completely insane..Some parts are missing Professional Driver on a closed course....Do not attempt.Just because I'm a  dumbass don't mean that you can be too.So DON'T try any of this **** l do at home.
Reply:My old Matchless motorcycle used to have Stellite valve caps. They were extremely hard parts that would prevent wear on the valve end. I can't imagine that it would weld very nicely or if used as a filler..Miller Millermatic 252Miller Syncrowave 200Liincoln AC-DC 225Victor O-A Set
Reply:Originally Posted by zapsterWhy in the world are you using Stallite for "filler"??...zap!
Reply:Maybe contact the manufacturer.  They seem to have a tech staff that might be able to help.  If they solve the problem, let us know what the secret is.http://www.stellite.com/products_ser...s_cast_rod.asphttp://www.stellite.com/products_ser...electrodes.asphttp://www.stellite.com/products_ser...bular_wire.aspInteresting stuff.  Apparently extremely hard alloy of cobalt and chromium with some tungsten.  From what I can gather, an existing layer of stellite is weldable.  Can't find out more about how to do it though other than passing references to the need for preheat and controlled slow cooling.
Reply:Found another article that talks about stellite welding on dies.  Calls for 800F preheat, weld while in furnace, back in preheat furnace to equalize temps, and then slow cool.http://www.forgingmagazine.com/full_story.php?WID=11904Seems like a PITA.
Reply:You haven't done much work around steam yet?
Reply:I'll bring the butter "Every choice you make will effect at least one other person"
Reply:clams   ---butter---  oh  and  beer   (cold )MMMMMMMMMMMMMMMMM  good stuff
Reply:HI everibody, this is my first post!!!!I´ve worked A LOT with stellite.-First step: WHich base material are you using? Martensitic, austenitic??? It helps you to calculate the preheat temperature.-There are tables to calculate the preheat temperature depending in the carbon equibalent of the base material.-Be carefull not to rise the interpass temperature (use a gas natural torch if needed - the same to preheat).-Be sure that the base material is not contaminated (in case it is a casting)-Cool softly (but get there cuickly) in vermiculite or similar.-Avoid two layers, if you need more hardness or less dilution, get it changing the welding parameters.Thats all folks!!!
Reply:Welcome B.A.    Thanks for the helpful post!!!Best regards, KbnitI r 2 a perfessional
Reply:There are several types of stellite, either chrome carbide / tungsten carbide in a nickel matrix.The chromium carbide types are extremely hard and craze cracking is natural. Tungsten carbide types don't crack.IMO, stellite has no place on valve seats - wouldn't machine too well, however the tungsten carbide types may machine up to a rough finish. Its primary use is wear resistance as an overlay on top of various base materials either inside pipes / firttings to cope with erosion, or on contact parts in refining / earthmoving etc etc.All the stellite would need to be removed and the whole seat overlayed with appropriate consumables. If you provide more information about service conditions, I may be able to assist with a repair method.
Reply:Stellite is very commonly used for valve seats.  It's the only thing that holds up to high pressure saturated steam, especially in throttling applications.Last edited by 76GMC1500; 09-04-2008 at 04:39 PM.
Reply:It also used to be used for replaceable valve seats for vehicle engines, and long ago for lathe toolbits and similar metal cutting tools. I think the carbide inserts have made the latter use obsolete.
Reply:I have performed valve repairs on turbines and stea, lines on ships using stellite #6 R-CoCr (i think) . We used GTAW for the process and a 700 degree preheat. Seemed to get better results using a backhand technique if I remember right. It has been many years. I am sure the manufacturers information is uthe best to go with.Have a nice dayhttp://www.weldingdata.com/
Reply:Originally Posted by kbnitWelcome B.A.    Thanks for the helpful post!!!Best regards, Kbnit
Reply:Originally Posted by chrispc66There are several types of stellite, either chrome carbide / tungsten carbide in a nickel matrix.The chromium carbide types are extremely hard and craze cracking is natural. Tungsten carbide types don't crack.IMO, stellite has no place on valve seats - wouldn't machine too well, however the tungsten carbide types may machine up to a rough finish. Its primary use is wear resistance as an overlay on top of various base materials either inside pipes / firttings to cope with erosion, or on contact parts in refining / earthmoving etc etc.All the stellite would need to be removed and the whole seat overlayed with appropriate consumables. If you provide more information about service conditions, I may be able to assist with a repair method.
Reply:Apologies, I understand automotive valve seats can be repaired with stellite based consumables, and this is properly completed using plasma transferred spray technology, and finished using machine grinding techniques.I was referring to the seats within gate valves in a process application, and machining using conventional techniques as part of a refurbishment regime.If the original valve seats were overlayed with stellite, they would need to be ground using purpose built equipment to obtain a sealing face. This can be repaired, however the grinding may be impossible, unless it's returned to the original manufacturer - Probably cheaper to buy new.If valve seats originally overlayed with stellite need repair, I would look to alternative consumables after machining off the stellite.Last edited by chrispc66; 09-08-2008 at 08:18 AM.Reason: typo!
Reply:BABaracusCrack repairs in stellite may highlight cracking in base material, with propagation through the overlay.Chrome carbide stellite usually craze crack - not considered detrimental to wear resistance. These types should not be used where cracking is undesirable, eg: internally clad piping and components. Used only where heavy impact / abrasion is present.Tungsten carbide stellite should not crack, based on tungsten spheroids in a nice ductile nickel matrix. These are normally used in pressure applications and valve seats etc, where cracking cannot be tolerated, and a sealing face can be ground.Preheat for stellite work depends on the BM requirements, however high preheat may exarcebate craze cracking in all stellite overlays. A serious crack in stellite overlays may be masking a more serious problem.Cheers
Reply:Hello again chrispc66.I ussually use stellite 6, "normally used in pressure applications and valve seats etc, where cracking cannot be tolerated, and a sealing face can be ground".Which kind of crack is a craze crack? Sorry, my vocabulary is very poor...And what does "may highlight" mean?Thanks!!!
Reply:'Craze cracking' occurs in some thin, hard material when the top layer has a good bond with the tougher material below but the surface layer gets a series of small, interlocking cracks throughout it. Something like tempered glass bonded to the plastic inner layer for auto windows; when that cracks, it still holds together as small pieces. Anyway, the small cracks don't matter for some applications such as dirt abrasion, but would cause problems for a sealing surface on a valve face.
Reply:Originally Posted by Oldiron2'Craze cracking' occurs in some thin, hard material when the top layer has a good bond with the tougher material below but the surface layer gets a series of small, interlocking cracks throughout it. Something like tempered glass bonded to the plastic inner layer for auto windows; when that cracks, it still holds together as small pieces. Anyway, the small cracks don't matter for some applications such as dirt abrasion, but would cause problems for a sealing surface on a valve face.