cast streel-mild steel

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Intersting one. I got called out to a repair site by another experianced welder. he was having problems with welding a casting on a back hoe. He told me he had made 5 attempts to repair this unit and always had the same end result- cracks.  We discussed his prep and welding perameters on the phone on my drive out. He was doing everything right except his post weld cool down was not slow enough ( at least not for me).  When I got out there I seen what he was working on and found it to be cast steel welding to mild steel. So he was not using the right rod. None the less he listened to me and I listened to him and went on my way back to the shop. A while later he calls and says he wire welded it and it still cracked. The outside temp was in the 30's and I told him to keep it heated after the weld and very slowly bring it back to normal. He did do that and got it to hold without cracking. Would you guys agree that the stress's from cool down were working against him and that with a controlled slow cool down he avoided cracking, or did he get lucky ?  I have welded plenty of cast steel and iron over the years and with cast steel I never treated it any different then mild steel, this was the first time I had seen it where cast steel needed the loving care of cast iron. Anyone else experiance this same thing ?  I love to learn and this was a very interesting situation and thought I would share it and see if there is more to learn from this.Dan.Repair Specialties LLC
Reply:Cast steel welds almost the same as regular steel, afterall, many beams are "continuously cast" steel.  How thick is the metal?  Depending on the thickness of the steel, it may require preheat.  I don't know what everybody's rule of thumb is and I don't get much experience with the thick stuff, but I've always heard 3/4" up requires preheat.  30 degrees is pretty cold for welding.A lot of cracking problems have to do with how rigid the pieces being held are restrained.  If both pieces are securely restrained, the chances of cracking are much greater as they will try to pull apart as they cool.
Reply:preheat to 500 and maintain 400 on the interpass. peen everything except the root and the cover. wrap up afterwards and let it slowly cool."Retreat hell, were just fighting in the other direction"Miller Trailblazer 302, Extreme 12 VS, Dimension 400, Spectrum 375, HF 251D-1, Milermatic 251 w/ spoolgun  Hypertherm 1000Lincoln sp 1702000 F-450 to haul it
Reply:Hopefully the material hasnt crystalized from all the other repairs done to it. With proper prep and if you let it cool slowly, it should hopefully be good as new(400 degrees Per inch of thickness per hour is used if im remembering right) but then again you are welding cast steel to miild steel hmm, another thought, id try to weld a few beads across the cast steel and then after weld the mild steel too the weld beads on the cast instead of laying a bead frome one to another, that may help in some way, always stringers on cast too. just some thoughts on it.Nothing Ever Got Done By Quitting, Never Give Up.
Reply:Originally Posted by DanMIntersting one... ...I got called out to a repair site by another experianced welder. he was having problems with welding a casting on a back hoe...  ...I have welded plenty of cast steel and iron over the years and with cast steel I never treated it any different then mild steel... ...this was a very interesting situation and thought I would share it and see if there is more to learn from this.
Reply:Originally Posted by backuprollerpreheat to 500 and maintain 400 on the interpass. peen everything except the root and the cover. wrap up afterwards and let it slowly cool.
Reply:Hmmm, is backup roller a fellow cav trooper? I was 3rd ACR. I have done a lot of cast steel to mild steel welding over the years while working in the oilfield. Most if not all welded on bearing housings are cast steel. I have never had cracking problems ever. Now keep in mind these are heavy castings welded to heavy beams. I always pre-heated, but never to any specific temp and used 7018 for all passes. By the time you lay on five or more passes of 5/32 you have put in a lot of heat. When finished I just let it air cool with no post heat. Maybe I just got lucky but I never had a crack. I also never attempted it in 30 degree weather and probably wouldn't. I just don't think it's a good idea because it would probably cool much too rapidly. In cold weather I brought them inside and when finished set them up with a turbo heater pointed right at them and just left it for a few hours. I have also welded on a number of wellheads (and they don't care how cold it is they just want it done) even in the middle of ice storms. Most wellheads of any size are cast steel. I always built a fire in the head, and then went about rolling out and prepping the casing. Usually by then the fire had burned down and we would set the head and I would weld it out. Once again always with 7018, and hydro test afterwards. I never had problems with cracking except on the inside welds when testing and this turned out to be caused by testing to too high a pressure. Never go more than about 70% collapse pressure, lol. I was just doing what thr drilling superintendent told me to. But they usually agreed on the pressure once I explained how that is determined and why it wouldn't work.The difference between art and craft is the quality of the workmanship. I am an artist.
Reply:"Cast steel" is just regular steel, no magic about it. Your friend needs to carbon arc the area "another experianced welder" repaired to remove ALL of his repair. If he run's the carbon arc correctly he'll be able to see when he passes through the limits of the other guys repair, the color and grain will change. Then I'd just insure a quick heat (100 degrees would be plenty) and weld it normally with 7018.Anything worth doing is worth doing RIGHT
Reply:I have never had a problem with it, just prep the area(gring, Arcair, or whatever), preheat, and weld. I use any LoHy rod(7018,8018,9018,10018, etc...) and all is usually well. Tempil sticks are your friend by the way.Disclaimer; "I am just an a$$hole welder, don't take it personally ."
Reply:Was this a Case backhoe?   Seems I read a factory speced procedure for repairing the boom.
Reply:Originally Posted by welderman1I was taught to peen the root. What is your reasoning here.
Reply:[QUOTE=Jolly Roger]Hmmm, is backup roller a fellow cav trooper? I was 3rd ACR. 2nd ACR Polk, 4th Cav Schweinfurt, 1-15 Inf Benning, 15th Cav Knox, 3-73 Armor Airborne Bragg"Retreat hell, were just fighting in the other direction"Miller Trailblazer 302, Extreme 12 VS, Dimension 400, Spectrum 375, HF 251D-1, Milermatic 251 w/ spoolgun  Hypertherm 1000Lincoln sp 1702000 F-450 to haul it
Reply:I was 3 ACR, Ft. Bliss, 108 MI, Wildflecken, been to Schweinfurt many times, got my first tattoo there.The difference between art and craft is the quality of the workmanship. I am an artist.