Fluxcore & rebar?

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My buddy seen some guys stealing some of his steel to scrap. While chasing them he rolled his SA250D.He has this lowpay gig welding rebar grids. The mill uses the grids to hold the refractory in the bottom of the latel. He asked me to take it over for him until further notice.I tried to use Hobart Fabshield 21B .045 flux core, figuring it would go faster.  When I started tossing them on the ground, they were breaking apart. It was the weld that was actually breaking. So ended up just using 7018 because thats what he does and never had an issue. These are not rocket science. They are not critical. I was just wondering why the FC didn't work? It was cold out with a really good wind at times. Rebar was ambient temp. I did try to turn up the heat and speed to move faster. Does FC turn sour if you run it hot? But I think some of the ones I welded at normal settings broke also."Where's Stick man????????" - 7A749"SHHHHHH!! I sent him over to snag that MIC-4 while tbone wasn't looking!" - duaneb55"I have bought a few of Tbone's things unlike Stick-Man who helps himself" - TozziWelding"Stick-man"
Reply:I have welded a lot of rebar doing embeds. As long as the rebar says W400 on it, its weldable, otherwise it will give you problems. Hard to say with out seeing the welds. Normally cracking or braking welds means either the weld was improper or the material is hard and needs preheat. Also are your welds shallow and hot? Sometimes shallow welds crack easily. Post pics if you can.
Reply:I believe I read on here last year that rebar is not the best to try and weld, might want to do a site search for rebar and see what comes up.
Reply:Originally Posted by oxygen454I have welded a lot of rebar doing embeds. As long as the rebar says W400 on it, its weldable, otherwise it will give you problems. Hard to say with out seeing the welds. Normally cracking or braking welds means either the weld was improper or the material is hard and needs preheat. Also are your welds shallow and hot? Sometimes shallow welds crack easily. Post pics if you can.
Reply:Originally Posted by Big65moparI believe I read on here last year that rebar is not the best to try and weld, might want to do a site search for rebar and see what comes up.
Reply:rebar isnt crap metal. in a structure it withstands considerable loads. It is not mild steel, and as mentioned, most grades of rebar are not weldable. The rebar I weld onto bent plate to tie into the slab is not the same grade as what the rodbusters put in their dowels. I should learn the specifics; but the stuff I touch is always bundled and marked "weldable".Weldanpower 225 G7Ironworkers Local #24
Reply:Originally Posted by Stick-manMy buddy seen some guys stealing some of his steel to scrap. While chasing them he rolled his SA250D.He has this lowpay gig welding rebar grids. The mill uses the grids to hold the refractory in the bottom of the latel. He asked me to take it over for him until further notice.I tried to use Hobart Fabshield 21B .045 flux core, figuring it would go faster.  When I started tossing them on the ground, they were breaking apart. It was the weld that was actually breaking. So ended up just using 7018 because thats what he does and never had an issue. These are not rocket science. They are not critical. I was just wondering why the FC didn't work? It was cold out with a really good wind at times. Rebar was ambient temp. I did try to turn up the heat and speed to move faster. Does FC turn sour if you run it hot? But I think some of the ones I welded at normal settings broke also.
Reply:Only meant crap in the instance that most  rebar is difficult to weld and after some thought I remember that I tried doing that last year in school with stick and not liking the results at all.  As for its intended purpose for structural reinforcement in cement structures theres no doubt that it is worth its weight in gold.
Reply:Pictures would help , i do welding on poured wall foundations and havent had problems. We overlap 3" and make a 2" weld at each end , it is run thru a curbing machine with two runs of rebar in each wall. Weld with Miller Passport .035 fluxcore , normally burn it a little on the Hot side.
Reply:Turning up the amps using flux core wire can work against you. You will get deeper penetration, but will be mixing more of the high carbon base metal with the fill metal. The resulting weld profile will probably be more concave, and the lighter slag will result in a faxter quench rate. Like Donald said, when you take short cuts and deviate from engineered procedures, all bets are off. A lot of welders who are very qualified will argue that it can or can't be done based on their personal experiences, but the fact that you working under less than ideal conditions also worked against you.
Reply:This might be one of those instances where "ignorance is bliss".  No one ever told me that rebar wasn't weldable, so I've been happily welding it for over 40 years with both stick and mig.  I make my own fireplace gratings out of it too.  Maybe I've always been lucky in getting "weldable" rebar?Miller Syncrowave 350Millermatic 252/ 30A spoolgunMiller Bobcat 225g w/ 3545 spoolgunLincoln PowerArc4000Lincoln 175 Mig  Lincoln 135 Mig Everlast 250EX TigCentury ac/dc 230 amp stickVictor O/AHypertherm 1000 plasma
Reply:Originally Posted by DougAustinTXThis might be one of those instances where "ignorance is bliss".  No one ever told me that rebar wasn't weldable, so I've been happily welding it for over 40 years with both stick and mig.  I make my own fireplace gratings out of it too.  Maybe I've always been lucky in getting "weldable" rebar?
Reply:Originally Posted by Pro-FabBeen there too. I welded it for years, untill I was on a site where someone used it for ladder rungs and one snapped off under a man's weight. I have never used it for critical applications since, no matter what grade it is.
Reply:If you really want to know how to weld rebar and see drawings of connections and so forth get the AWS publication. AWS/ANSI D1.4-98Now it is called D1.4/D1.4M:2011 STRUCTURAL WELDING CODE - REINFORCING STEELIt is back order now it says. (popular booklet)Last edited by Donald Branscom; 03-27-2011 at 07:48 PM.AWS certified welding inspectorAWS certified welder
Reply:I will try to get a number off of the rebar mon. I got it pre cut into 9" and 13" pieces in two drums. I will also take a pic of the finished product. I am going to guess it is the cheapest rebar available."Where's Stick man????????" - 7A749"SHHHHHH!! I sent him over to snag that MIC-4 while tbone wasn't looking!" - duaneb55"I have bought a few of Tbone's things unlike Stick-Man who helps himself" - TozziWelding"Stick-man"
Reply:I have done a fair amount of splicing rebar in precast concrete panels. Used a combination of joint details 13-19, and 13-28, always used Lincoln's NS-3M. 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:I have 6 sets of wps and pull test certs for welding rebar all with E71T-8-H16  class flux core wiresVantage 500's LN-25's, VI-400's, cobramatics, Miller migs, synch 350 LX, Powcon inverters, XMT's, 250 Ton Acurrpress 12' brake, 1/4" 10' Atlantic shear,Koikie plasma table W/ esab plasmas. marvel & hyd-mech saws, pirrana & metal muncher punches.
Reply:Like I said, this is not critical. Any bad weldor could do this job.Here is the marking on the rebar.Here is one completed. They refer to them as "chicken ladders". Four welds....DONE!Here is the empty jig I whipped up really quick.Here is the jig loaded up to weld four at a time. "Where's Stick man????????" - 7A749"SHHHHHH!! I sent him over to snag that MIC-4 while tbone wasn't looking!" - duaneb55"I have bought a few of Tbone's things unlike Stick-Man who helps himself" - TozziWelding"Stick-man"
Reply:"Chicken ladder jig"  That'll have folks scracting their heads wondering WTF. So those things must be disposable then? Just what is it they get used for?  Besides chicken ladders that is. "The things that will destroy America are prosperity at any price, peace at any price, safety first instead of duty first, the love of soft living and the get rich quick theory of life." -Theodore Roosevelt
Reply:You know, I have used rebar for years on the farm.  We actually made a scaling drum out of 3/8 Rb to take scales off of fish.  Ive also used it for rungs on ladders that went some 15 feet high ( top of a food pellet hopper). Now that I think of it,  Ive welded probably a ton of the stuff....table legs.....tool hangers...cable hangers...weed draggers...My gosh, all the weed draggers.  I have always used 6011  1/8th to weld it.  Glad no one ever got hurt??!! JDLincoln IdealArc 250 AC/DC  w/ tigLincoln Ranger 8Miller Millermatic 140Victor Cutting setForney gas welding setMilwaukee power-tools3 legged dog named SpeedyFridge full of Diet Coke1 angry wife2 loud kids
Reply:It s about to repair a ferro cement boat.have a look to the picshttp://www.flickr.com/photos/awab/?u...95045387cd4daeThe front is damaged. To repair I need to build a new armature. Should I weld the new rebar to the old one.I just bought the boat and have no experience with welding.What is doing the heat to the old cement.need your guys advice in the matterthankspeter