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Hi all. This is my first post, so it might be a bit long. I looked for the answer to my question using the search option, but I cant seem to find it. In my search though, I found that this seems to be a very friendly and helpful sight (why is it that sites frequented by people who can actually do something seem so much more polite than sites where people argue about theory and abstract stuff.) Anyway, on to my question. I am a newby trying to learn to oxy/acet, weld from a book. With practice, my welds have gotten fairly pretty. The problem is they are weak. I have been practicing butt welding two ¼ x 1 by about 4 pieces of mild steel long-ways. Then I use a vise and big crescent wrench to break them apart. Since they always break right along the seam I assume they are weak (is it just a myth that a good weld should be stronger than the surrounding metal?) I am using the appropriate pressure, tip, rod etc. according to the book; but even the welds with good penetration (80%-90%) break. The metal along the break looks grainy; kind of like cast or pot metal. Is this what my book calls crystallization? If so, Im confused. The book says that its caused by too much gas pressure, usually oxygen. But if the pressure is correct at the regulator and the flame is neutral, what can I adjust? Any advice you can give me would be really appreciated. I can give you pressure, tip size etc. info if it will help. This post was getting pretty long already though. Thanx in advance. Vince.
Reply:This thread is useless without pics.. ...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:Sounds to me like you might be boiling the puddle. Like zap said, get us some pics. How clean is the metal, what type of rod, will help as well. Im assuming your running no more than 5cfh on both regulators. Are you bending 180 degrees? Remember also, that a weld will be stronger tensile wise, but will not be as ductile as regular steel, thus it will crack on mild steel before the steel will in extreme bends (like 180 degree fold right on the weld). As long as the toes of the weld hold (the edges of the weld). When we bend in class, we usually do 90 deg tests and 1 inch radius 180 deg. curved bend tests on butt joints/square grooves. I have yet to have one fail . BTW you can test the oxygen theory, just go slightly carbonizing to see if there is any change. Im curious as well.Various GrindersVictor Journeyman torch200cf Acet. 250cf oxygenLincoln 175 plus/alpha2 gunLincoln v205t tigLincoln 350mpEsab 650 plasmaWhen you can get up in the morning, Its a good day.Live each day like its your last.
Reply:You need 100% penatration to be as strong as the plate. Broken welds look crystalized anyhow. Try welding both sides or work on your prep before welding. What are you using for filler?Torch welding is almost a lost art, but the BEST place for a welder to start and learn heat control.DavidReal world weldin. When I grow up I want to be a tig weldor.
Reply:Hey guys, thanks for the replys. I will try and get some pics up. It may take a while though (I will post a new thread). To clean the metal I run an angle grinder over the top of the flat and the edge to be welded until it is bright shiny, then brush it off. The rod I use is 1/8 inch........rod. I asked they guy at the welding shop for rod to gas weld mild steel and bought a few pounds of it. Is there more than one type for gas welding? I have been using 4 pounds each on the regulators. Doolittle, I am curious about how you do test bends in class. What is the proper method, what is pass and fail? Should I put the practice piece in the vise right down to the bead? Should I grip the piece with the wrench right down to the seam? If one of my bends makes it to 90 degrees, does the weld have to be perfectly in tact to be considered a "pass?" What is a one inch, radius test? Thanx again.P.S. That is not the first time I heard the advise about learning to torch weld first. The money I spent on this set-up would have bought a good chunk of mig welder. I wanted to start with the basics though and be the best all-around welder I can be. The mig or arc will be next
Reply:Well, you need to ask for either r45 or r60, both weld nice. Ive had good luck with radnor rods. The way this guy does his testing is he will take for example, a t joint and bend away from the weld side (your stretching the weld). He mashes it until the t is as flat as it can get. For butt and square groove joints, he takes a test plate and cuts about a 2 inch strip out perpendicular to the weld, then grinds the weld flush with both the back and front sides of the piece. He then has a jig, it bends the sample into a 'U' shape. Its got a chisle type (its rounded on the pointy end) plunger that pushes the test piece between two stand offs. Really simple. He has this nice press brake to do em on. I guess for a do it yourselfer you could take a piece of channel and deepen it (weld on some extensions to deepen the channel, then get yourself a piece of 3/4 steel to make the plug or punch, or whatever we want to call it. Your channel will have to be pretty sturdy stuff, say 5/8. After you get pretty good with the torch, get a tig. It will be an easy changeover. You can also learn stick with a tig welder which is another can of worms, and seems to be my weak spot when welding stuff up. A small mig is wonderful to have around as well. Gas welding for me, is never as pretty as a tig weld.Various GrindersVictor Journeyman torch200cf Acet. 250cf oxygenLincoln 175 plus/alpha2 gunLincoln v205t tigLincoln 350mpEsab 650 plasmaWhen you can get up in the morning, Its a good day.Live each day like its your last. |
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发表于 2021-9-1 00:11:02