Why did this weld break ?

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I have welding for years and most stuff stays together. For the most part kinda of a Mechanic that can weld a little. Not a pro by any means. I had to replace the round bar on my lowbed that the two trap doors were welded to and one of them broke and I though I had burned it in pretty good. There is no real weight on so I was surprised that this happened.The 2 inch round bar is brand new. I ground everything down clean. I used 1/8 7018's but I will confess the rods are probably 20 yrs old.  A friend of mine who is a welder said he thinks I used too much heat, old rods and should have preheat the metal with a rosebud.I included a pic of the welder and settings.The 3rd pic down is the other side. it did not break(yet??). Attached ImagesLast edited by acesneights1; 05-22-2016 at 07:53 PM.Lincoln Ranger 8Lincoln 140c MigLincoln Tombstone(doesn't everybody have one ?)Miller 200Diesel/Heavy Equipment MechanicLead Plant Mechanic Municipal Water
Reply:BTW this is what I am working on.Thanks for any advice. Attached ImagesLincoln Ranger 8Lincoln 140c MigLincoln Tombstone(doesn't everybody have one ?)Miller 200Diesel/Heavy Equipment MechanicLead Plant Mechanic Municipal Water
Reply:This is what the trapdoor that broke off looks like. Attached ImagesLincoln Ranger 8Lincoln 140c MigLincoln Tombstone(doesn't everybody have one ?)Miller 200Diesel/Heavy Equipment MechanicLead Plant Mechanic Municipal Water
Reply:Looks like you may have held to long of an arc length.Don’t pay any attention to meI’m just a hobbyist!CarlDynasty 300V350-Pro w/pulseSG Spool gun1937 IdealArc-300PowerArc 200ST3 SA-200sVantage 400
Reply:did you run your bead from top down with the joint in the vertical  position?i.u.o.e. # 15queens, ny and sunny fla
Reply:Here would be my guess. Old rod that was wet.Klutch 220si mig , stick, and dc tigHobart 140 AHP ALPHA 200X 2016Lotos LTP5000DSmith O/P
Reply:How clean did you get the the steel to be welded.Doesn't look like you got any penetration on one side of the round bar
Reply:Originally Posted by tinker001Old rod that was wet.
Reply:Well look man 20 year old 7018? Was it sealed the whole 20 years? ditch that **** unless it was 20 years old sealed the whole time up untill now.   Use fresh 7018. Excalibur or esab atom arc. Turn ur machine down to the 125 amp mark.  Turn the arc force knob down to 3 or something like that for 7018. U have it on 7 now.  Hold a tight arc.Dynasty 200DX   (2014)Millermatic 211 (2015)Optrel 864   (2014)Smith Medium duty MBA 30510 (Xmas 2014)Tennsmith 16ga 4ft finger brake (2015)Trailblazer 325 EFI and excel Thermal dynamics Cutmaster 82Miller maxtron 450
Reply:No the rod was not sealed. Just in an open cardboard box. They have gotten damp many times from condensation.Should I also pre heat the metal ?Also I am now worried about the other side. Should I cut it back apart or weld over it. It did not break.Lincoln Ranger 8Lincoln 140c MigLincoln Tombstone(doesn't everybody have one ?)Miller 200Diesel/Heavy Equipment MechanicLead Plant Mechanic Municipal Water
Reply:The round bar was new steel so just a quick dress with the 4 inch.The Trap door I cut most of the excess off as flsuh as I could with the torch then finished grinding it flat with my Milwaukee 7 inch grinder. It has some serious balls.Lincoln Ranger 8Lincoln 140c MigLincoln Tombstone(doesn't everybody have one ?)Miller 200Diesel/Heavy Equipment MechanicLead Plant Mechanic Municipal Water
Reply:Originally Posted by outdoortWell look man 20 year old 7018? Was it sealed the whole 20 years? ditch that **** unless it was 20 years old sealed the whole time up untill now.   Use fresh 7018. Excalibur or esab atom arc. Turn ur machine down to the 125 amp mark.  Turn the arc force knob down to 3 or something like that for 7018. U have it on 7 now.  Hold a tight arc.
Reply:Those rods your holding look bigger than 1/8, if it was me I would be cleaning the metal real good, preheat with a propane weed burner or rose bud and set the welder at 200 amps. I can't see what the welder is set at in the picture but if your using 5/32 rods or bigger I would start at 200 amps and keep a tight arc length.Good luck!
Reply:Originally Posted by acesneights1Ok, here's where I'm gonna look stupid but I'd rather learn something so...I never actually knew exactly what that knob does. Can you explain what exactly it does ?(the arc force knob)
Reply:All that rod is supposed to do hold the blocks in line. If there was any gap on the top of those blocks so they are not aligned properly one or the other will break. I hope with our welding skills the way they are you d.on't do a lot of work on that lowboy
Reply:No problem man thats what this forum is for. Learning.   Basically it make the puddle/bead more "buttery" or more "stiff".  Lower is more buttery and higher is more stiff. 7018 and most rods i would prob keep the arc force around 3 and go from there. Feel free to experiment too.   Acr force also makes it harder to "stick" your rod.  So rods like 6010 i would maybe turn it up to seven or nine.   U should be able to get a good bead with 7018 or any rod for that matter with the arc force turned all the way up or down, so this isnt critical, but just one more thing u could do to help urself out.Dynasty 200DX   (2014)Millermatic 211 (2015)Optrel 864   (2014)Smith Medium duty MBA 30510 (Xmas 2014)Tennsmith 16ga 4ft finger brake (2015)Trailblazer 325 EFI and excel Thermal dynamics Cutmaster 82Miller maxtron 450
Reply:Originally Posted by acesneights1Ok, here's where I'm gonna look stupid but I'd rather learn something so...I never actually knew exactly what that knob does. Can you explain what exactly it does ?(the arc force knob)
Reply:Originally Posted by mikecwikI thought that was the fine control not arc force. Which would put you at about 165 amp but it does not look like that in the photo. Can you check the output of the machine?
Reply:Originally Posted by outdoortNo problem man thats what this forum is for. Learning.   Basically it make the puddle/bead more "buttery" or more "stiff".  Lower is more buttery and higher is more stiff. 7018 and most rods i would prob keep the arc force around 3 and go from there. Feel free to experiment too.   Acr force also makes it harder to "stick" your rod.  So rods like 6010 i would maybe turn it up to seven or nine.   U should be able to get a good bead with 7018 or any rod for that matter with the arc force turned all the way up or down, so this isnt critical, but just one more thing u could do to help urself out.
Reply:Originally Posted by kctgbAs far as I know the knob you seem to describe is a percent of what the amperage setting is. If your welder is set at 100 amps and the knob is set at 5 it's 50 percent of 100 amps. I'm not an expert on engine welders but that's how I understand it.
Reply:Originally Posted by theweldorAll that rod is supposed to do hold the blocks in line. If there was any gap on the top of those blocks so they are not aligned properly one or the other will break. I hope with our welding skills the way they are you d.on't do a lot of work on that lowboy
Reply:Originally Posted by docwelderdid you run your bead from top down with the joint in the vertical  position?
Reply:Was the long side of the trap door hanging down?
Reply:Did you remove all the old broken weld from both pieces?Did you get both pieces cleaned up with all the rust and scale removed prior to welding. The material looks fairly heavy, if your not welding hot enough some preheat would have helped. I also suspect that the round bar is cold rolled. Your weld appears to have a lot of undercut on the top toe of the top pass. That creates a weak spot right there.JasonLincoln Idealarc 250 stick/tigThermal Dynamics Cutmaster 52Miller Bobcat 250Torchmate CNC tableThermal Arc Hefty 2Ironworkers Local 720
Reply:First and foremost get a welder to weld this. No disrespect but those weld are no good. If those rods are 1/8 you should be welding this at around 125 amps not 165 amps like you had it set.If this round stock is hot roll or cold rolled and the bar you're trying to weld it to is mild steel, a little preheat wouldn't hurt. But if it's a 4140 round stock more heat would be required.And with this size of steel start with a couple passes of 1/8 and finish it with some 5/32at around 170 amps. And don't cheap out get some new rods. I wouldn't weld anything structural that operates on public roads with 20 years old rods.Last edited by Daniel-B; 05-22-2016 at 10:47 PM.Originally Posted by snoeproeDid you remove all the old broken weld from both pieces?Did you get both pieces cleaned up with all the rust and scale removed prior to welding. The material looks fairly heavy, if your not welding hot enough some preheat would have helped. I also suspect that the round bar is cold rolled. Your weld appears to have a lot of undercut on the top toe of the top pass. That creates a weak spot right there.
Reply:Originally Posted by Daniel-BFirst and foremost get a welder to weld this. No disrespect but those weld are no good. If those rods are 1/8 you should be welding this at around 125 amps not 165 amps like you had it set.If this round stock is hot roll or cold rolled and the bar you're trying to weld it to is mild steel, a little preheat wouldn't hurt. But if it's a 4140 round stock more heat would be required.And with this size of steel start with a couple passes of 1/8 and finish it with some 5/32at around 170 amps. And don't cheap out get some new rods. I wouldn't weld anything structural that operates on public roads with 20 years old rods.
Reply:Should I ground the round bar flat ? See attached pic. Attached ImagesLincoln Ranger 8Lincoln 140c MigLincoln Tombstone(doesn't everybody have one ?)Miller 200Diesel/Heavy Equipment MechanicLead Plant Mechanic Municipal Water
Reply:Some of the best weldors practice and experiment all the time , Jody and CEP come to mind. Welding and bend testing. I'm a hobbiest, and I'll admit that I don't do that. I might go a month without welding. When I do a project, The welds at the end of the project ALWAYS look better than at the beginning. And I always tell myself the next time I'll at least run a couple of rods before my next project. And almost never do. A bead can look good , and be weak, but if it looks bad, it WILL be weak! IMHO, with welds like those, grind them out and reweld. Just my 2 cents.
Reply:I asked around some of the excavating guys around here and they all do like me, fix their own. Trying to see if I can find a local guy who is reputable.Lincoln Ranger 8Lincoln 140c MigLincoln Tombstone(doesn't everybody have one ?)Miller 200Diesel/Heavy Equipment MechanicLead Plant Mechanic Municipal Water
Reply:Sad part is a good friend of mine was up the day before and he was a certified welder from DOT. Might have to try and coax him back for another visit.Lincoln Ranger 8Lincoln 140c MigLincoln Tombstone(doesn't everybody have one ?)Miller 200Diesel/Heavy Equipment MechanicLead Plant Mechanic Municipal Water
Reply:Can appreciate that you want to do it yourself but, if I'm reading this right, you're trying a pretty tough weld in an awkward position.  Might have been beyond your experience.  Couldn't see the backside and wound up with just a couple weak birdcrap tacks.  The backside is critical to lock in the piece so it's weight can't leverage the front.  Any chance you could weld a flatbar on the trapdoor before you position it and so leave yourself an easier weld? Attached ImagesLast edited by OldSparks; 05-23-2016 at 09:08 AM.
Reply:Originally Posted by acesneights1Thank you, I normally don't tackle stuff this big. If I knew someone good around here I'd clean it up and have it welded but I live in the sticks and the only reputable welder I know are in NY. Even a half *** weld should have held. There is not much stress on it which surprises me why it broke in the first place.Like a lot of people, I was a heavy truck/equipment mech who spent a good 30 yrs working for cheap *** dirt merchants who wanted it fixed and if I wanted to keep my job, I better learn how to fix it. If I know something isn't safe I will not run it down the road hence coming here and asking for help. If I still don't feel confident I will try and source someone but who's to say just because someone has a sign on their truck and a welder in the back that they are any better than me ?I don't know anyone in my area.
Reply:Originally Posted by OldSparksCan appreciate that you want to do it yourself but, if I'm reading this right, you're trying a pretty tough weld in an awkward position.  Might have been beyond your experience.  Couldn't see the backside and wound up with just a couple weak birdcrap tacks.  The backside is critical to lock in the piece so it's weight can't leverage the front.  Any chance you could weld a flatbar on the trapdoor before you position it and so leave yourself an easier weld?
Reply:Originally Posted by DennisKI can identify with your situation as I, too, live out in the sticks, and there are a lot of times just buying your way out of a problem won't work.   I may be wrong, but if your weld didn't have porosity problems, the age of your rods wasn't the cause.  Clearly, you didn't get the penetration that was needed.  As suggested previously, preheat can help, along with more amps.  Perhaps that 2” rod acted as a kind of heat sink to the bead.  From my own experience, I have made welds where, at first glance, seemed good, but what I was really doing was just stacking molten metal on top of itself without really getting into the base of my weld.  Pay particular attention to the edge of your bead – the edge should not just sit on top of the base – it should be well into the base.   As to welding over a bad weld …. not a good idea.    I've never worked on a lowboy, but perhaps you also had an alignment problem where, for example, welding it open seemed to work, but when closed, it created a bind where combined with a bad weld, can break on its own.  Whenever you heat steel, it will cause a distortion.
Reply:You need 100% weld. What I mean by that is, no void in the weldment with slag in it. Grinding like in your drawing, you'll have to do it anyways but may at the end of the bar as well wouldn't hurt. I  like I stated before start with a smaller rod so you can get deep in the joint and finish with a bigger rod so you don't have to weave so much. Weaving shouldn't be wider than 3 rods wide. If wider it creates to much stress when the weldment cools and shrinks, which is prone to cracking.And I would do the other side as it doesn't look better than the side that broke.
Reply:Originally Posted by Daniel-BYou need 100% weld. What I mean by that is, no void in the weldment with slag in it. Grinding like in your drawing, you'll have to do it anyways but may at the end of the bar as well wouldn't hurt. I  like I stated before start with a smaller rod so you can get deep in the joint and finish with a bigger rod so you don't have to weave so much. Weaving shouldn't be wider than 3 rods wide. If wider it creates to much stress when the weldment cools and shrinks, which is prone to cracking.And I would do the other side as it doesn't look better than the side that broke.
Reply:This is a good thread as I have just learned something new.  I didn't pay much attention to the difference between hot and cold rolled rods, other than my concern with tolerances, but I just learned that cold rolled rods have a greater content of carbon.  This would make welding a bit more difficult.  Preheating would be a definite aid - especially when dealing with a 2" rod.
Reply:7018 is basically a low penetrating rod. I would run the first pass with 6010, then switch to 7018. Attached ImagesDon’t pay any attention to meI’m just a hobbyist!CarlDynasty 300V350-Pro w/pulseSG Spool gun1937 IdealArc-300PowerArc 200ST3 SA-200sVantage 400
Reply:Originally Posted by acesneights1I have welding for years and most stuff stays together. For the most part kinda of a Mechanic that can weld a little. Not a pro by any means. I had to replace the round bar on my lowbed that the two trap doors were welded to and one of them broke and I though I had burned it in pretty good. There is no real weight on so I was surprised that this happened.The 2 inch round bar is brand new. I ground everything down clean. I used 1/8 7018's but I will confess the rods are probably 20 yrs old.  A friend of mine who is a welder said he thinks I used too much heat, old rods and should have preheat the metal with a rosebud.I included a pic of the welder and settings.The 3rd pic down is the other side. it did not break(yet??).
Reply:Originally Posted by WNY_TomBdo not pay attention to the "you can use 7018 wet". i once heard a guy get asbestos in his mouth saying taste not bad and asbestos never hurt him. some people think the rules of the universe do not apply to them
Reply:Starting with 6010 would be a good idea for sure.
Reply:Originally Posted by CEPBig part of my work was building falsework for cast in place bridges, and over passes. Here in the north west they never give you a tent. All welding done in the rain, with wet 7018.
Reply:Originally Posted by Daniel-BStarting with 6010 would be a good idea for sure.
Reply:Originally Posted by WNY_TomB.depends on weld inspector and the steel alloy. i have been on jobs inspector required .1) a rod oven so 7018 rod was not out over 4 hours. if it was over 4 hour out of oven it was not to be used.2) preheating of steel was required when under 50F and if steel was over a certain thickness. typically over 1" thick.3) weld area was required to be dry. if that meant erect a enclosure with a roof thats what we did. usually just scaffolding with a tarp tied to it.if i argued with weld inspector i would have been removed from the weld site and have had to turn over my weld certification stamp. i was required to stamp my welds to identify who welded what
Reply:Originally Posted by WNY_TomB.not if it was a steel alloy or free machining steel that required low hydrogen procedure. 6010 flux is cellulose based and gives off water vapor when welding.bevel the joint properly will give you the penetration.when it breaks along side of weld or the haz or heat effected zone that typically is a lack of preheat and lack of low hydrogen welding being followed
Reply:free machining cold rolled round steel is often confused with regular cold rolled 1018. i work in a machine shop. i can tell you that mistakes happen..sulfur bearing steel can barely be welded following low hydrogen weld procedure with 7018. even then for critical applications they will say get the proper steel as it is not worth the risk..i worked at places that cold rolled was never welded even if just 1018. they always got hot rolled 1018 just to be on the safe side
Reply:Originally Posted by WNY_TomBfree machining cold rolled round steel is often confused with regular cold rolled 1018. i work in a machine shop. i can tell you that mistakes happen..sulfur bearing steel can barely be welded following low hydrogen weld procedure with 7018. even then for critical applications they will say get the proper steel as it is not worth the risk..i worked at places that cold rolled was never welded even if just 1018. they always got hot rolled 1018 just to be on the safe side
Reply:Long arcing, like said, might be the problem, dunnoIf you were welding overhead ("upside down"), you have to keep the rod shoved into the steel, and wait for the puddle to build.  Don't move on just because you think you've filled the joint.  Wait for the puddle to fill, and tries to droop down.  Then move on.  Most people tend to weld too fast overhead.  It's a balance between surface tension, and speed.  Wait till it looks like it's about ready to drop in your lap.Don't mistake slag for a puddle, it's a common mistake."Any day above ground is a good day"http://www.farmersamm.com/
Reply:1/8 at 175 will show a bunch of spatter, but it's not a killer deal.  Simply move faster to compensate for the heat.  But, it's not ideal.Spatter is a sign of too much puddle agitation, and will cause what you're seeing in aggravated situations.  The arc is trying to blow the metal.Arc blow can occur.  it's a matter of magnetic fields trying to push the puddle in directions you don't want it to go.  Generally characterized by the arc straying outside the line of travel.  The solution is generally to run the weld towards the corners, not away from the corners.  Arc blow will definitely occur when welding irregular shapes.  All about corners, angles, and shapes.Wet rod, or something that has been exposed to moisture........should still run pretty good, despite what the experts say.  Been there, done that.  Only question is whether the weld is sound in such a circumstance, not the appearance.I see globs, it tells me something was terribly wrong, and you should have seen it under the hood."Any day above ground is a good day"http://www.farmersamm.com/