Buildup Cast Steel Gear

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I'm looking for some info on how to buildup Cast Steel. I have a giant gear from a rock crusher and the gears need to be built up again. I just got out of trade school and never touched cast steel until today at work. We were using 7018, but it looked as if the weld wasn't sticking very good, you could see a faint line between the weld and the cast steel. We then brought in a different rod, and I can't remember the name of it now :S, but the beads ran poor with alot of porosity on the first pass or 2. But after multiple passes the porosity pratically disapeared. And the same thing happened with each tooth. First few passes;porosity, the rest, almost fine.
Reply:Are you sure of the material? Run a grinder across it and see how it sparks.John -  fabricator extraordinaire, car nut!-  bleeding Miller blue! http://www.weldfabzone.com
Reply:Just curious, but is the gear Cast steel or Cast iron?  Cast steel will usually weld without much trouble, but cast iron on the other hand sometimes reacts as you described when welded with mild steel rods.  Have you tried a nickel rod yet?  I haven't ever built up an entire gear, but I have built up a chipped or broken gear tooth with silicone bronze, brass, nickel, even 309 stainless at times.I'm a Lover, Fighter, Wild horse Rider, and a pretty good welding man......
Reply:That's what I was thinking Jackson, it might be cast iron. He may need/try some Nickel 55 rod on it.John -  fabricator extraordinaire, car nut!-  bleeding Miller blue! http://www.weldfabzone.com
Reply:I'm with ya on that one John,  I think all the gears I have ever dealt with were cast iron,  there could very well be some made of cast steel, (I honestly am not sure), but I don't think I have ever run across one.  I say a  nickel 55 or a 309 stainless in a tight.I'm a Lover, Fighter, Wild horse Rider, and a pretty good welding man......
Reply:I thought it was nickle 99... ...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:There's a 55 & 99. I have always used the 55 but that is what is the easiest for me to find around here.The 99 is a 99% nickel weld and has a lot softer weld deposit for easier machining.  The 55 is a 55% nickel that has a higher strength and less prone to cracking in the heat affected zone.Last edited by Hammack_Welding; 07-05-2007 at 05:03 PM.I'm a Lover, Fighter, Wild horse Rider, and a pretty good welding man......
Reply:Ahhh 'Cause all I have ever seen is 99... Carry on!...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:Teeny red sparks Cast Iron.  Yellow sparks with tails, Cast Steel or better.Right?DavidReal world weldin.  When I grow up I want to be a tig weldor.
Reply:As been said already, it's probably cast iron, at least it sounds like it is, from the description. Ni-rod here will run you about $42/lb. That's kind of high, I know. I have done quite a bit of cast iron work, while Ni-rod is the best, 309 stainless rods will work in pinch. I always try to apply alot of pre-heat, with both rods. I personally believe the hotter the better, but I'm sure there is a pint were too much is not good. Anything around 300-350 degrees is sufficient.  Hope this helps.
Reply:Hey guys, thanks for all the responses. It really helps. I'll run a spark test tommorrow. I did preheat before welding, but even preheating didn't cure the porosity. The 7018 beads looks are fine, but as I mentioned when i grinded the weld down I could see the line where the 7018 met the cast iron/steel.These rods (Ni-Cr I think) I started using after are really shiney and the problem is the porosity on the beads. But it looks like they're taking to it better. Oh, the rods are Blueshield  Xtreme ? and have a light Blue flux on the outside....dunno if that helps....but that's the best I can do till tomorrow.
Reply:Newfie, I did a little searching and i think the Blueshield Xtreme is an alloy rod.  I think what you are looking for is a Blueshield MNR 55 I've never used that brand before just going off what i have run across looking around the web.  Easiest way is to call your welding supplier and tell them you need some nickel rods.  They should know what you need.  Just curious but are you building up every tooth on the gear?  It looks to me with the time involved in doing that they could have bought a new gear.   Just curious.  Let us know how it comes out. ~JacksonI'm a Lover, Fighter, Wild horse Rider, and a pretty good welding man......
Reply:Hey Hammack, ya, the rods I'm using now have Nickel in them. (Ni-Cr) If i recall correctly was what was written on the included pamphlet....and I'm pretty sure you guys are right about the cast iron. I was using a small grinder with a zip disc to take out the porosity welds and there wasn't a long stream of sparks. Wasn't many sparks at all actually. From th elooks of the MSD sheets on http://www.ca.airliquide.com/en/busi...tions/msds.asp the ones I'm using only have 7-13% Nickle and 15-30% Chromium. The other rod you mentioned  MNR Cast 55 has 40-60% Nickel. And the MNR 99 is pretty much all nickle.I'll relay this stuff tomorrow and see what the boss thinks, but I assume the MNR 55 and MSN 99 would be better then what I'm using now ???btw, I have 2 of these to do. And it  looks like they were built up before as well. Not sure about why they won't buy a new one. Maybe it's old equipment, but I know there will be alot of work to it. After I weld it, the Machinests have their work cut out for them.Last edited by Newfie#2; 07-05-2007 at 08:35 PM.
Reply:Just because there is nickel in the rod, doesn't mean it is a 'nickel' rod meant for use on cast iron!!Your Blueshield Xtreme rod is made and meant for welding 'high' alloy steels, like 4130, 4340, tool and die steels, spring steels, etc.  The right Blueshield rod for use on cast iron would be the Cast55, Cast99, or Tri-Cast rods.  See http://www.blueshield.ca/en/docs/pdf...hieldMNR_E.pdffor a PDF chart on selecting the right Blueshield rod.
Reply:Well, after  a Spark test, and from others point of views, it's Cast Steel.Those blue shiled extreme were cracking and had porosity. Also, the teeth had been surfaced before, and it looks as if the old welds are starting to come up. I don't think there's much hope...
Reply:I don't think there's much hope...
Reply:Cast steel instead of cast iron still can cover a pretty wide material range.  Just that you are dealing with less carbon in the steel than you would have in the cast iron.  How -much- less and what else is in the steel are still not known.Preheat, clean, preheat, clean more, preheat, then maybe try welding.Also, if this is a big piece, how are you doing the preheat and then weld and then post-weld heat soak and slow-cool?The gear -may- have had special materials used in the metal or special final heat treatments done for the desired mechanical properties.Or it might just be plain old cast steel that is putting up a struggle.And if the machinists have the ability to remachine gear teeth, why don't they just make a new gear?  Even just a toothed-bushing that you then weld onto the remains of the old gear after the teeth are removed?
Reply:Moonrise, that was something that crossed my mind and why I was asking if this was just a few teeth or the entire gear.  If the machinist have the capability to completely recut gear teeth then I would think making a ring gear then turning the older teeth off, and welding the new ring gear on might be a better solution,  or just making a new one.  but I'm just brainstorming now.  If you can post some pics of the gear I think we all would like to see them.I'm a Lover, Fighter, Wild horse Rider, and a pretty good welding man......
Reply:Lots of things to try, if it is steel, before giving up.Excavate as much as needed to get to GOOD base metal. If there are any cracks in the base metal, say, under a previous buildup layer, or in a hardface surface, or from stress, that are holding oil or crud, it will fight you forever. You gotta either dig it out or cook it out. Cooking it out goes back to lay it in and grind it out until the new material is satisfactory. If it is hardface, grind it off. The buildup won't last, even if you manage to get it to fuse in.Ni-55 or Ni-99 can help with higher carbon steels, as with cast iron. If there is hardface applied, nickel rod won't help. grind the hardface off before buildup.Ni-Cr rods often are the ticket, but when you get crud coming through, grind it out and re weld. Sometimes second or third time gives you good fusion and good metal. Once there is a good butter layer on, then go back to the 7018. My bet would be that it is crud from service in the base metal, based n the description, though I'd only go 70% confidence on this. There ARE some goofy steels. The symptoms fit contamination, though. Probably oil, but may also be cmponents of the rock being crushed if the gear wasn't protected, especially if the rock is sulfer bearing.