Stick weld strength

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I have asked a few folks around the shop, and no one seems to know the answer yet wont just say "I dont know"I would like to know about the structural strength of various rods. When I T welded two half inch plates together then beat them silly, I couldnt really tell the difference in weld strength with 7010, 7018 or 6010. What is all the hype about 7018 for? The welds dont seem to be any stronger with low hydrogen. For repairs requiring welds that are subject to torsion and flex like trailers what is your rod of choice and why?
Reply:The strengths of the rods are more complex than it first seems.First, the 'rated' strength (60KSI, 70KSI,etc) are minimums as welded strength in controlled conditions, and are generally exceeded in practice.Second, the ductility, toughness (especially at low temperature), and a host of other properties are often important. If they arn't important in your application, then you will see little difference in the final weld properties.The ow hydrogen properties of 7018 are dead critical in some applications, but tend not to be important for thin, plain, low carbon steels (les than 1/2" or so). Thicker steels, higher carbon, and alloy steels tend to crack in or near the weld if lo hydrogen processe arn't used. Most hobby welders, and many professional welders, will never see a weld where it does matter. Many welders will also never see a weld that needs preheat, togh many wil find preheat useful.You won't 'see' the strength difference without a maching to test the welds in a controlled way, set to measure the applied forces. Beating with a hammer may test toughness, to a point, will show ductility to a point, and will test for excessive brittleness. It will not show strength in a quantitative way, other than if the weld is expected to be beaten with the same hammer in service (which some are, or the logical equivelant of this, at least, making the BFH test a nice quick and dirty validation test)In practice, most jobs are fine with whatever rod you prefer to use. Some need the characteristics of a particular electrode type.
Reply:Specific rod property tendancies as welded:7018 (properlywelded) has good low temp toughness and high ductility compared to 6010. Matters at temps below freezing.Higher strength rods (8018, 9018, etc) tend to have higher alloy content at strength goes up, be more sensitive to improper procedure during welding, and be more sensetive to preoper application (high temp service, low temp service, impact, etc)Some rods are more tolerant of contamination than others: 6010 is moderately tolerant (no, this is not a license to weld through grease and rust... clean the weld zone) 7018 is less tolerant of  organics, but is quit good at washing oxides and slag out of the material (again, not a license to avoid cleaning, but if I run into slag trapped under a weld on in a lamination in the material, I prefer '18 to most any other rod)Higher strength rods often make WEAKER welds on low strength material, as well as raising the weld cost. How weaker? The higher strength weld metal tends to lead to stress concentrations adjacent to the weld zone in many weld configurations, and tends to trap more stress in the material.
Reply:Thanks for all that info Enlpck
Reply:I posed a similar question a few weeks ago.  http://www.weldingweb.com/vbb/showthread...rence+quantify
Reply:awwww enlpck, i was just about to burn me an 18 on a greasy spring hanger, ha.ha.ha.
Reply:What's all the hype about 7018? Well, If I was only allowed to use only 1 type of rod it would be 1/8" 7018.
Reply:Originally Posted by tresiWhat's all the hype about 7018? Well, If I was only allowed to use only 1 type of rod it would be 1/8" 7018.
Reply:Just weld a stick of 6010 to a plate, then bend it back and forth to break it off.Do the same with 7018.  You WILL see the difference.    The work I do specafies "Low hydragen" and rods of E70XX.  SO 7018 is the winner. Some times it also requires a preheat of 225* f to make sure there is no moisture in the plate.  The last job I was on, I was allowed to use ER70s-6 with Co2 gas.  The next guy that came along had 7010 and was sent on his way.  I also had to show my cert before I started the job.  Bare wire has "low hydragen properties" because its eneloped in a gas. It is 70,000 tensil strength, so I was Ok.I think especially for repiar work 7018 is the way to go.  Just my opinion, yadda yadda yadda.Sorry for poor speeling today.DavidReal world weldin.  When I grow up I want to be a tig weldor.
Reply:E7018 is a low Hydrogen, Iron Powder, 70,000 pound tensile strength rod. For certified welds, it must be kept in an oven to ensure the quality of the low hydrogen flux coating and must be used within 4 hours of removal from the oven. It can be redried once in the oven. Preheat is especially needed when material thickness reaches about 1/2" or greater. Certification test plates, 1" thick for structural welding, must be completed with E7018 1/8" rod from the oven. I spent a year and a half in school to learn Mig and to become certified, which, as it turns out, begins with stick welding 1" plate, using 1/8" E7018 rod. Little did I know that I was starting off with the wrong process!  E7018 is a benchmark filler material.City of L.A. Structural; Manual & Semi-Automatic;"Surely there is a mine for silver, and a place where gold is refined. Iron is taken from the earth, and copper is smelted from ore."Job 28:1,2Lincoln, Miller, Victor & ISV BibleDanny
Reply:This is some great info. Thanks guys!!And then, after so much work...... you have it in your hand, and you look over to your side...... and the runner has run off. Leaving you holding the prize, wondering when the runner will return.
Reply:Originally Posted by David RJust weld a stick of 6010 to a plate, then bend it back and forth to break it off.Do the same with 7018.  You WILL see the difference.
Reply:I guess I need a lot more practice with 7018. I was trained by a downhill weldor using XX11 rods and I got pretty decent at down hilling. For working on repairs I have more confidence that I am getting quality welds with the XX11s. My uphills with 7018 are pretty rough. They seem to want to flow creating a ridge down the center of the bead. My flats and overheads look fine with 7018.
Reply:Originally Posted by StuckwldrI guess I need a lot more practice with 7018. I was trained by a downhill weldor using XX11 rods and I got pretty decent at down hilling. For working on repairs I have more confidence that I am getting quality welds with the XX11s. My uphills with 7018 are pretty rough. They seem to want to flow creating a ridge down the center of the bead. My flats and overheads look fine with 7018.
Reply:Shouldn't make any difference on mild steel.  Most mild steel is 40,000 tensile so the welds done correctly are stronger than the base metal.
Reply:Originally Posted by gtrmanShouldn't make any difference on mild steel.  Most mild steel is 40,000 tensile