Stellite #6 on large valve parts

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Hello everyone I'm new to the forum. Just signed up. I have some welding questions. Can someone please inform as to the proper way to lay stellite #6 on large valve parts. This is what we've been doing so far: 1. Cut off all the old cracked stellite in a lathe. 2. Preheat the piece to about 150 deg. F. 3. Lay 309 with a mig running at about 200 amps using .045 wire. 4. Machine back the 309 to a smooth finish after it's cool. 5. Preheat the piece to about 150 deg. F. 6. Lay the stellite #6 using 5/32 rod to attain a build up of .040 to .080 inches running a good 300 amps. 7. Bring the temperature of the piece down slowly over a period of about 36 hours until it's room temperature. 8. Cut it to finish size. Problem is when it's cooling off you'll hear the piece ringing out with these pings and when we dye check they really stand out. These pieces are around 16" in diameter and about 4" thick. My thought is one or both of these things. Either the piece of material is too thick and there is a lot of expansion and contraction going on (I've never had any problem with much smaller items. They're literally glowing red hot after welding) or the 309 we put as an underlayment does not have sufficient penetration and there are unseen voids in the 309. A buddy of mine told me when they layed the 309 at another facility they were running at about 450 to 500 amps. Then again they may have running 1/16" wire. Does anyone have any ideas as to what the problem may be. It doesn't actually happen all the time and I think it's because we just get lucky.Also is there really any way to repair cracks in stellite.ThanxJim
Reply:What is the recommended interpass temperature  for both the 309 and the Stellite #6, also is the 309 hard wire or fluxcore.
Reply:The 309 is hard wire. Don't know what the interpass temp is supposed to be. I would imagine the stellite #6 has a much higher one than the 309. Problem is the stellite is rock hard and it's still glowing red hot. There doesn't seem to be a malleable state. It's either liquid or hard.Last edited by jmnew51; 03-24-2015 at 10:35 PM.
Reply:Another question, can you get stellite #6 on spool for MIG. The owners tell you cannot, only stellite #21. Don't know how true it is. Also what type of shielding gas would you need for it if you could.Jim
Reply:I think you should contact Stellite company and follow their recomendations.  Is 309 the right material to use as base material?  I sure don't know but there may be an issue with dis similar metals growing at different rates.  It has been years sense I have messed with any Stellite.  What we used on extruder screws was tig welded on, then had to be ground to size. A lathe would not touch it.  The original screws were made of D2 tool steel and heat treated.  I recall we kept the part crazy hot while welding and put it in a heat treat furnace and ramped the temps down.  I hav no idea what the temps were.  Was over 30 years ago.  Dan D.Manipulator Of Metal
Reply:jmnew51What machine-tool-cutter are you using to hog-out 'the old cracked Stellite' in the lathe.Usually, Stellite valve faces are 'Ground' then pressed in the valve body.Is your repair: welding a 'spent' pressed Stellite ring in the valve - and have you been successful before?'150 deg. preheat - glowing red hot - 36 hr. slope - 450/500 amps'.  These procedural incongruities make recommendations difficult.  'Does anyone have any ideas as to what the problem may be' - Yes.'Also is there really any way to repair cracks in Stellite' - No - but NASA is working on it.Opus
Reply:ULTIMET, a more ductile alternative to Stellite 6,  manufactured by Haynes Int'l recommends a maximum Interpass temp of 200deg F, www.haynesintl.com/pdf/h2099.pdfLast edited by ManoKai; 03-25-2015 at 05:44 AM."Discovery is to see what everybody else has seen, and to think what nobody else has thought" - Albert Szent-Gyorgyi
Reply:@ jmnew51 - see http://www.stellite.com/ProductsServ...0/Default.aspx.  Spec sheet for Stellite 'X' suggests the product is FCAW vice solid wire.  FCAW-S versus FGAW-G or MCAWA?  Acall to Kennanetal would resolve your question."Discovery is to see what everybody else has seen, and to think what nobody else has thought" - Albert Szent-Gyorgyi
Reply:Thank you for all your input. I will have to call Kennametal to get the proper procedure. Opus, we are using carbide on a lathe at very slow speeds to hog out the old stellite. We also are using ceramic inserts to do our finish cuts.Jim
Reply:At a previous job I welded probably several thousand pounds of 3/16" Stellite #6 and #12. We were welding large valves and there housings. We played with the heat per Stoody's recommendations and kept it at least 300° to 600°. As far as welding amperage we typically ran anywhere from low 200's to 300 amps at the most. We always had some cracking and was told it's simply the nature of the beast.
Reply:If you're just hard surfacing, cracks are OK. What we are working on are high pressure steam valves and any cracks on the surface will cause steam cuts in the valve surface.Jim