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Can someone explain why filler metal wants to explode when heated? I've seen this happen with both steel and brass rods. It seems better when dry flux is added (at least when doing some brass brazing last night). I'm thinking the metal is probably too hot, but it seems to happen fairly quickly after getting to the molten stage. Everything seems to be going pretty well, and then the filler pool pops and everything is gone. Doesn't make for much of a weld (or braze).I've tried searching for answers to this, but "pop" usually refers to the torch itself popping, and "explode" to the obvious.Hobart Handler 210Lincoln AC-225Smith Torches/Regs
Reply:I guess I'd have to be there to see it, but when it pops on me I turn the flame up a little. If the flame is too small it tends to back up in the tip causing a small explosion. JMHO, MikeOl' Stonebreaker "Experience is the name everyone gives to their mistakes"Hobart G-213 portableMiller 175 migMiller thunderbolt ac/dc stick Victor O/A setupMakita chop saw
Reply:What is your application? If you are welding on a pipe or tube that is capped, a build up of internal pressure will blow out the molten filler on you. This is also an issue with TIG. When this happens, you have to let the piece cool down and then continue.
Reply:I think I know what you are describing. It's been 30+ years since I did any OA stuff so I'm a bit hazzy on the exact issue. I believe you got the torch too close to the metal and the reflected heat has overheated the tip causing the pop. Maybe this may help someone else understand and explain it better..No government ever voluntarily reduces itself in size. Government programs, once launched, never disappear. Actually, a government bureau is the nearest thing to eternal life we'll ever see on this earth! Ronald Reagan
Reply:You are overheating the puddle either keep moving once you have the puddle started adding filler or pull away the torch.
Reply:I guess this is probably it, but it just seems like it would take more heat. Am I basically boiling the metal?Application wise, it doesn't really matter (plate, tubing, whatever). It does seem to happen less on clean metal, so I wondered if it was something to do with impurities in the metal. I don't think I have the torch too close (it can happen at any distance). Before it happens, I can start to see more "turbulence" in the puddle, again sort of like it's starting to boil. Shortly after that the puddle will explode and throw molten metal everywhere.Hobart Handler 210Lincoln AC-225Smith Torches/Regs
Reply:Are you setting your pressures and adjusting your flame properly?
Reply:Originally Posted by thomasalvaCan someone explain why filler metal wants to explode when heated?... Everything seems to be going pretty well, and then the filler pool pops and everything is gone.
Reply:Thanks Rick, your write-up makes sense. I do tend to try and keep the tip of the inner flame on the puddle, but last night I was having to move it way back because I was brass brazing/welding a very thin (probably 29 gauge or less) watering can spout to a steel threaded ring (so the spout can attach to the can). Probably in this case I should have been using a micro torch to be able to better control the flame.I'll try your techniques maybe later today if I get a chance to compare the difference.Thanks again.Hobart Handler 210Lincoln AC-225Smith Torches/Regs
Reply:Yikes, 29 gauge (0.0135 inch) is really thin! You might be better off brazing that for sure.In my course, my comments referred to welding 1/16" (0.0625 inch) thick steel plates with a Harris #4 tip (56 number drill, orifice 0.0465 inch diameter - same as a Victor #2 tip) and 1/16 inch diameter R45 steel filler rod.Rick V 1 Airco Heliwelder 3A/DDR3 CTC 70/90 amp Stick/Tig Inverters in Parallel1 Lincoln MIG PAK 151 Oxy-Acet
Reply:Yeah, it didn't take anything to burn right through that stuff. That was not something I typically work on, but my wife really liked the watering can so I thought I would at least give it a shot. It's better than new now and the bronze looks nice to boot.I tried your suggestions on some 1/8 tubing tonight, and I can see it's going to work better. I didn't have any pops this time, and the bead itself was nicer also. Need more practice of course...Hobart Handler 210Lincoln AC-225Smith Torches/Regs
Reply:When an O/A torch pops, it's not the metal exploding. It's the torch going out due to lack of oxygen or fuel, then relighting itself from the puddle. When it relights it blows the molten metal out of the puddle. To be safe you should turn off the needle valves when the torch pops and make sure you don't have a flashback.Pops are backfires and are caused by one or more of 5 things*:- insufficient fuel or oxygen - turn fuel and/or oxygen up- tip too close to workpiece, smothering flame - back off workpiece- too small a tip - use larger tip- debris in tip - clean tip- loose tip - tighten tip on torch*As I've been instructed in class.
Reply:amen 6530lincoln weld pak 100 hdlincoln ranger 225gxt ac/dcoxy/acetylenepuroxcw202 victor fc100harris model 85harrismodel 16oxweld w24roxweld w17
Reply:I'll keep an eye on this, but the flame isn't visibly changing when this happens, and the torch can be two inches away the whole time.I have seen what you are talking about though. A while back I was almost out of acetylene and trying to weld some thick pipe. I had the torch really close to compensate and I could see the flame extinguishing and reigniting, so all of the things you listed would apply in that case. With the bronze brazing though, the metal would just explode if it got overheated. I had a good neutral flame and the torch was at least an inch or two away the whole time. I would have used a smaller tip if I had one.This popping thing doesn't seem to happen so much with thicker metal and with steel rod. I'll try it again with some thin metal and bronze filler to see if it happens again.Hobart Handler 210Lincoln AC-225Smith Torches/Regs
Reply:Its been a while, but as I recall if the pop is from insufficient heat (not enough flow or too small a tip) the metal will 'crackle' before the pop. It never happened to me but the guy in the booth next to me sent molten metal on my sweat shirt. Note - unless its 100% cotton sweat shirt, don't wear it welding.Fortunately it was a very slight burn and healed in a week or so.Anyway, instructor said when you hear the crackling, go closer with the torch or else it will pop. Once you got everything under control, turn up the heat (more gas + oxygen).As a beginner class, everyone was a little cautious and tended to go too low on gas flow/pressure etc.Con Fuse!Miller Dynasty 350Millermatic 350P-Spoolmatic 30AMiller Multimatic 200Hypertherm PowerMax 1000G3Miller Maxstar 200DX
Reply:Interesting that low heat can cause it. I was trying to avoid giving it too much heat because the base metal wanted to burn through, but enough obviously to keep a puddle going. I'll experiment with that too when I get a chance.Hobart Handler 210Lincoln AC-225Smith Torches/Regs
Reply:If you're welding very thin metal, use th esmallest torch tip that you have available. Practice on heavier material until you get a feel for how much heat is required. |
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发表于 2021-8-31 23:28:06