I was wondering what rod you guys use for gas welding on sheetmetal. I have been using some Radnor ER70S2 1/16" rod, and hammering it after I weld it. It seems like it is hard when I hammer and dollie it, and I would like something more malleable. The local welding supply has been of very little help. I did try (maybe I shouldn't say this) using bailing wire, and it actually works pretty well. Lower melting point and super easy to work after its welded. So what do you use?
I gas weld all the time. Try some heavier mig wire. if your gaps are tight you don't need much filler at all, just a bit to insure the weld has a slight crown to it.
Most coat hangers are mild steel and work fine, just keep the paint burned off a ways back to not contaminate the weld. Oh and your wife will get pissed when she finds a bunch of her hangers missing, I know... GV
Just curious - if mig welding is hard & brittle why is different when gas welding with mig wire? Is it to do with the different temps in the welding process?
this is a great question and something I've always wondered about too. I've always figured that it was due to the heat or some property of the MIG arc, like the ozone or the like. but maybe someone with a more direct knowledge will chime in.
It has to do with the amount of heat put into the work piece, and how long it takes to cool down. A mig, its point, click, and tada.. you have a weld. Tig you strike an arc on the piece, wait for a puddle, and proceed. Gas you have the flame on the piece, wait for a puddle, and go. You end up heating the work piece much more with tig and especially gas. You can see this in the heat effected zone(the area that turns blue). The mig weld heat zone is far smaller than that of the gas weld. Having more heat in the piece causes a longer cool down time(obviously). This is where I get shakey on this... I'm no metalurgist, so someone may correct me, but the way I understand it is the longer cool down time allows the carbon molecules in the steel to settle into a different crystal form that allows for more ductility in the metal. Quenching the weld will stop this from happening, because you shorten the cool down time.
Bingo! Steel molecules change their orientation with temperature. The crystalline structures are known as body centered cubic and face centered cubic. This structure has a very direct effect on the property of the steel. When you quench a hot piece of steel, depending on the temperature it will "freeze in" a higher temperature crystalline structure and give it different properties. These different temperature driven phases of steel have different names like Martensite etc. MIG welding tends to cool too fast freezing in the higher temp. structure and hence a brittle weld, regardless of the type of wire used. Thanks for the responses. I'm going to try just using some .025 Mig wire for now and the next time I'm at the welding supply house I'll look for the RG45 or RG60.
Taught myself how to gas weld (we call it brazing here for some reason) on a 30 or 31 Model A tudor that I bought off a hunter for about $50.00 quite a few years ago. The body was in really nice shape but had over three hundred bullet holes in it. Filled everyone one of them with coat hanger and oxy acetylene. For what ever reason the hunters seem to like shooting at the back half and pretty much stayed away from the cowl and doors. Sold the body to guy that used it in a restoration project.
i useda lot of wire coat hangers on my 54 chop. worped the shit out of it but when you hammer weld it, it actually helps with the cooling process. any shop that gets a uniform service will have penty of hangers to give away. if anyone needs any in my neck of the woods, ive got a lot left over.
thats what happens, just finished taking a material science class for mech engineering, and what happens is the longer it takes to cool down the more time the carbon has to diffuse into a steady state, adn since that state i believe is much more ductile it wont be as brittle.
I used tie wire and a burning torch to do some welding on a construction site, you do what you have to do.
Harbor Frieight sells Hobart 3/32 RG45 (copper flash) works good with chromemoly tubing, and is larger to work faster. It's what we used in welding school, so I've never seen fit to use anything else on steel.
The 70 on the front end of the rod number means 70,000 psi ultimate tensile stress, which is pretty strong, and therefore, hard. (not brittle). In this case, you want something with a lower tensile like the low carbon steel wire in coat hangers, or a lower tensile welding rod.
If you want softer metal you have to let the metal cool down slow. Hammering the metal while It's hot and even after the metal has cooled down makes the metal hard again. ER70S2 is actually Used normally for TIG welding and it has a higher amount of hydrogen(I think) in the weld rod. You probebly noticed that the rod is kinda like a sparkler when the torch flame touches it. It shoots haot sparks all over your arms and leaves tiny little burns on your skin. I made the mistake of using TIG rod while oxy/ acytilene welding in class. If I remember right I had to heat up the metal really hot in order to get the rod to fuse with the metal, it was also harder to move the puddle. the kind of rod your gona want is RG45, or RG60 for sure. This is kinda off but the good TIG welders out there can weld just as fast as The MIG welders depending on the thickness of the metal. So it is possible to keep the heat down with TIG. But we all know that the best thing to do to keep the heat down is to not weld from point A to point B in one pass. Skip around to prevent warping.
It actually doesn't pop much. The welding supply that I bought it from said it could be used for both TIG and O/A, but then again, I have been lead in the wrong direction before. I'll go tomorrow and try to pick up some of this RG45 stuff. Thanks for the help.
Having the wrong flame will also make your filler rod into a sparkler. I use ER70S2, RG45 and ER70S6 (MIG wire) for gas welding. I might try the "mystery metal" coathanger idea, but I've heard nothing good about it. The ER70 is, indeed, a bit harder to planish than the RG series. With 2 MIGs in the garage, I tend to find myself doing a lot of gas welding on sheetmetal! Less "violent" and easier to work. Tim D.
WOW it's nice to know I'm not the only coat hanger jockey. I thought sure I'd get ridiculed for using "junk wire". It can be tricky because the coat hanger is kinda thick for body sheet metal but you learn how to aim the flame. One of the last things I did when I sold my shop was grab all the uniform hangers. I'm really not THAT cheap. I'm just used to it and like it.
"If you want softer metal you have to let the metal cool down slow. Hammering the metal while It's hot and even after the metal has cooled down makes the metal hard again. ER70S2 is actually Used normally for TIG welding and it has a higher amount of hydrogen(I think) in the weld rod. You probebly noticed that the rod is kinda like a sparkler when the torch flame touches it. It shoots haot sparks all over your arms and leaves tiny little burns on your skin. I made the mistake of using TIG rod while oxy/ acytilene welding in class. If I remember right I had to heat up the metal really hot in order to get the rod to fuse with the metal, it was also harder to move the puddle. the kind of rod your gona want is RG45, or RG60 for sure." Actually...No, ER70S Does not have any H, Your thinking of SMAW filler rods such as 6010 wich has a high H concentration as where you're 7018H4R would be a low H concentration. GTAW filler rods do not typically work well while OXY/ACET. welding because there is no flux on the filler rod hense the "sparkler effect" formentioned. I would recomnmend a Silicon/Bronxe filler rod for a good tensile strength, flowability,finishing and paintability. Regards
Blair, bailing wire is the go, it's cold drawn low carbon steel wire. When you make a welded joint some of the carbon in the parent metal transfers into the filler wire increasing it's strength, hammering the weld improves the structure of the weld by refining the metal. The main benefit of this method is this, if you need to make complex shapes, or curve the sheet or plate, the weld will offer no resistance and will not distort the job. It also remains stable and will not crack when stressed. Another thing to try is shaving a strip off an edge of a parent sheet. We use this method when welding some exotic metals that must be polished and no welded joints should be seen. flatford 39, we refer to brazing as the joining of metals by the use of non ferrous filler wire, copper, brass, bronze and the like, this is done at a lower temperature than welding which typically uses carbon based filler wires, and requires higher temperature. To all the Mig afficionadoes, and I am one! (gas welding went out with button up boots) Mig welding is a form of Low Hydrogen welding no matter what simple Heat Treatment you apply, you cannot fully normalise the weld. Kitty litter is so-so. It can be done in a Heat Treatment furnace or if your'e like us blacksmiths you put it in a forging furnace for 30 minutes at the end of the day, close the door, turn the furnace off and let the job slow cool overnight. Get it Hot! hit it Hard!
Holy shit guys,,,,,,,,I never knew there was so much to know about gas welding. Been doing it since about 52 and never even looked to see what kind of wire I was using. Just went and bought 1/16, 3/32 or something, or coat hangers, and went to it. Stopped using coat hangers back in the 60's when my wife threatened me within an inch of my life if I stole one more of hers.
The Jalopy Journal
