Machinability of weld

admin

Does anyone out there know much about hardness of various filler materials as welded?Welders are more apt to be concerned with tensile strength.Machinists,concerned with hardness(rockwell).If I wanted to repair a part and machine it afterward,is one type of rod better formachining?I know tig rod comes in all steel types(d2,s7 tool steels etc.)but I'm talkingabout smaw electrodes.Is 6013 easier on cutting tools than 7018?Is there a rod made for post weld machining?Would annealing help?Miller a/c-d/c Thunderbolt XLMillermatic 180 Purox O/ASmith Littletorch O/AHobart Champion Elite
Reply:Some more info on just what you are trying to do would probably help. Stick seems an odd choice for most machining jobs I can think of. I've seen bores welded up with mig then remachined to correct for wear. I've seen shafts tigged or spray welded the returned. I guess I could see a cast iron block stick welded then remachined to do a repair, but stick is fairly heavyduty for most small jobs I can imagine..No government ever voluntarily reduces itself in size. Government programs, once launched, never disappear. Actually, a government bureau is the nearest thing to eternal life we'll ever see on this earth! Ronald Reagan
Reply:i  know that zapster used 7018 when he ran out of argon..
Reply:As DSW says, tig is often used for smaller, more intricate jobs for building up a part for machining.  I spent a year and a half as a welder at a machine shop and used stick for fabricating parts that had to be machined and also for parts that were to be turned or milled to rebuild worn areas.  For stick 7018, 8018 or what ever, was used as required to match the properties of the base metal being welded.  Had to follow all required preheats, postheats and inter-pass temps in order to maintain machineability.  Also very good weld practices had to be followed to avoid pin holes, trapped slag, cracking, etc.  Just as effective as an X-ray for finding a bad weld.  Cheat your preheat, even a small amount, and you may find a part that was too hard to machine.  Then the big guy would be there in short order to talk to you.  Luckily, I never had the need to come up with an explanation for a hard weld, but I have seen some pretty fast talkers.  Just not very convincing is all."The man of great wealth owes a peculiar obligation to the State, because he derives special advantages from the mere existence of government."  Teddy RooseveltAmerican by birth, Union by choice!  Boilermakers # 60America is a Union.
Reply:As DSW said, more information please. Stick would be a waste of time, from a production standpoint. Why do you want to anneal? and also when do you want to anneal, post weld or post machining? I would suggest post machining IMO I believe that the weld would become brittle, and the annealing process would change the molecular structure of the weld and the parent metal around the weld. which would happen upon welding anyway. I would suggest preheating and post-heating for your application, contact an engineer in material science aka metallurgist.
Reply:I was thinking of repairing worn shafts.(bearing froze,inner race spun on shaft,wearing shaft).I don't have tig.Would pre-heat prevent part from conducting heat away from the weld,causing rapid cooling/hardening of weld?Miller a/c-d/c Thunderbolt XLMillermatic 180 Purox O/ASmith Littletorch O/AHobart Champion Elite
Reply:Originally Posted by jpump5I was thinking of repairing worn shafts.(bearing froze,inner race spun on shaft,wearing shaft).I don't have tig.Would pre-heat prevent part from conducting heat away from the weld,causing rapid cooling/hardening of weld?
Reply:I really just want to build up the shaft  and be able to turn it down with a HSS lathe tool to fit the bearing.The effect on the strength of the shaft should be minimal.Miller a/c-d/c Thunderbolt XLMillermatic 180 Purox O/ASmith Littletorch O/AHobart Champion Elite
Reply:I'm going to use a carbide tool and 7018 as Zapster suggests.Miller a/c-d/c Thunderbolt XLMillermatic 180 Purox O/ASmith Littletorch O/AHobart Champion Elite
Reply:common steel shaft-- ok weld and machine. forged shafts, spindles on wheeled vehicles etc. --- be careful. make the spindle brittle and you lose a wheel when it snaps off. lots of agricultural implement spindles are turned steel shafts fabricated into axles and spindles, these are usually ok to build up and machine, and they aint usually high vehicle speed anyway. just keep in mind the end results if you induce a failure.
Reply:One thing to keep in mind though..DO NOT weld to a shoulder if the shaft has one..Start about 1/8" away from the shoulder and work "Outwards"Starting on the shoulder will bend the shaft badly..Start by cleaning the area as good as you can and then after every pass chip off the flux and continue..Go around the shaft..NOT down the shaft....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:Zapster-Good information about welding to a shoulder.Never thought about that but it makes perfect sense.CarlH-I wouldn't weld OR machine a spindle on a road going vehicle.     -ThanksMiller a/c-d/c Thunderbolt XLMillermatic 180 Purox O/ASmith Littletorch O/AHobart Champion Elite
Reply:MMCHUGH-I thought annealing before machining might make material easier to machine.Also productivity is not really an issue.Miller a/c-d/c Thunderbolt XLMillermatic 180 Purox O/ASmith Littletorch O/AHobart Champion Elite
Reply:jpump5- more then likely it will make it easier to machine, of course it depends on what type of annealing process you use. some may have a little have more benefit then others depending on application and type of ferrous metal. Normalization-is a process in which metal is cooled in air after heating in order to relieve stress. this is used for hardenable steel, can improve ductility and toughness of the steel.Process annealing- basically restores ductility so that the metal can be worked without breaking, ex:reduced risk of distortion of the work piece during machining, welding, or further heattreatment cycles. 500-1400 degrees depending on the alloyfull anneal-this creates a new homogeneous structure with decent dynamic properties. heat the item to about 50 degrees C above the austenic temperature the details for full anneal depend on the type of metal and the precise alloy.short cycled annealing- turns a normal ferrite into malleable ferrite. again details are metal specific.Hope this information helps, good luck on your project.
Reply:jpump5-- it was not my intention to insult your intelligence. I apologize if it was taken that way.
Reply:CarlH-No apology necessary, I didn't take it that way.btw shaft is for gravely garden tractor attachment.Miller a/c-d/c Thunderbolt XLMillermatic 180 Purox O/ASmith Littletorch O/AHobart Champion Elite
Reply:Originally Posted by jpump5Is 6013 easier on cutting tools than 7018?
Reply:Rick V-Good information.I think what I will do is weld on a scrap piece of shaft with 6013 and7018 and try turning it.Miller a/c-d/c Thunderbolt XLMillermatic 180 Purox O/ASmith Littletorch O/AHobart Champion Elite
Reply:Just to throw my 2 cents into the fray. I've done a good bit of stick build up in the past. I don't use stick very often any more since I've got some good wire machines which are much faster. However I firmly believe that 7018 makes a better quality buildup than either 6013 or wire. It machines better and is much easier to get a good finish on.Millermatic 252XMT 304'sDynasty 280DXHypertherm PowerMax 1250Miller Trailblazer 302 EFIOptima PulserXR feeder and XR Edge gun and more athttp://members.dslextreme.com/users/waynecook/index.htm
Reply:I tried welding a piece of shaft with 6013 and 7018 and then turning itto see if there is a difference in the machinability between the two rods..As you can see the welding didn't go real smoothly.Not unlike a large steel turd.I took an extra .060 off the dia. to get rid of some of the undercutting.(Just for the picture)With a little practice I can definitly make this work.I can't really say I see alot of difference between the machinability of the rods. Attached ImagesMiller a/c-d/c Thunderbolt XLMillermatic 180 Purox O/ASmith Littletorch O/AHobart Champion Elite