|
|
Hello all:Quick question on some T-joint MIG welds I was doing today with 1 inch Sch40 steel pipe. When I am done with the weld, there is a coating of black soot covering the weld. I have not seen this before so I don't know what I am doing wrong. My setup: Harbor Freight 171 with Selector set to 5 and Wire Speed at 7, C25 gas at 20 CFM, .023 Solid ER70S-3 wire. pipe cleaned with 80 grit flap disc before welding.Is this a normal outcome? I have not welded this material before so maybe not a problem after all. Soot brushes off with ease. I am fabricating a rack to hold raw material in a vertical format. Thank you for your patience. Take care. Burt
Reply:Originally Posted by fluvannabearHello all:Quick question on some T-joint MIG welds I was doing today with 1 inch Sch40 steel pipe. When I am done with the weld, there is a coating of black soot covering the weld. I have not seen this before so I don't know what I am doing wrong. My setup: Harbor Freight 171 with Selector set to 5 and Wire Speed at 7, C25 gas at 20 CFM, .023 Solid ER70S-3 wire. pipe cleaned with 80 grit flap disc before welding.Is this a normal outcome? I have not welded this material before so maybe not a problem after all. Soot brushes off with ease. I am fabricating a rack to hold raw material in a vertical format. Thank you for your patience. Take care. Burt
Reply:Labmaster02: Nope. Was painted but flap disc took care of that. Galvanized is nasty stuff on the lungs. Thanks for response. Burt
Reply:Was this new pipe ? Was the pipe purchased at a big box store ? If big box store purchase it must be import pipe which can do all sorts of things. Neighbor bought a piece and wanted me to thread it for him. Darn pipe was so hard it kept chewing up threads.Were you getting enough gas flow ? It may show 20 but is ?
Reply:BD1: The pipe came from frames used to hold up welding 5'x6' yellow curtains that I got at auction. Company made Stairs and Rails and had 6 screens up for auction and got them all for $20. They bought black pipe by the bundle for railings so figure this was from some of that. Used to work there as a CAD draftsman. As to the gas flow, I had it set at 20cfm when the trigger was pulled but do not know to judge if too little or too much flow. Could you give some guidance on that? I have been making tack welds on the raw material holder I am trying to build using this material and also using it as a project to improve my admittedly novice welding skills. Hope to learn as I go with this site and practice. Take care. Burty
Reply:Couple of thoughts.....If it were galvanized you'd end up with whitish yellow fluffy looking deposits.Not sure exactly what could be causing the black sooty deposits you say you're getting but if they wipe off easily and there's no underlying porosity it might not necessarily be hurting any thing for what you're building.One suggestion... get some other steel (like maybe some cold rolled 1018) and weld on it and see if you get the same black sooty deposits. If not I'd have to suspect it's something to do with the chemistry of the "black pipe" you've been welding on.
Reply:HT2-4956: Thank you for the response. Will give it a try on some 14ga 3"x8" pieces, I was able to have the former employer cut up for me from scrap. Been using it for welding practice. Got a 5gal bucket full a few years back and still have some left. It is HRS so will have to remove the mill scale. Got the 80grit flap disc for that. Any suggestions regarding knowing when you have the right C25 flow rate? Other than just trying different numbers and pick the one that works best. Take care. Burt.
Reply:Pics?
Reply:walker: If I can figure out how to post them. Not too familiar with the process. Will try tomorrow and see what happens. Thanks. Take care. Burt
Reply:Flap discs aren't the best for removing mill scale. Try a grinder disc.MM200 w/Spoolmatic 1Syncrowave 180SDBobcat 225G Plus - LP/NGMUTT Suitcase WirefeederWC-1S/Spoolmatic 1HF-251D-1PakMaster 100XL '68 Red Face Code #6633 projectStar Jet 21-110Save Second Base!
Reply:duaneb55: Thanks for the information. Will try a grinder on the 14ga pieces. The pipe is shiny bright when I remove the paint (Sampson red) using the flap disc. Just trying to eliminate sources of problems by making use of all the experience here. Take care. Burt
Reply:Originally Posted by fluvannabearHT2-4956: Thank you for the response. Will give it a try on some 14ga 3"x8" pieces, I was able to have the former employer cut up for me from scrap. Been using it for welding practice. Got a 5gal bucket full a few years back and still have some left. It is HRS so will have to remove the mill scale. Got the 80grit flap disc for that. Any suggestions regarding knowing when you have the right C25 flow rate? Other than just trying different numbers and pick the one that works best. Take care. Burt.
Reply:Another thought.... I see where you're running .023 diameter wire. To me that seems excessively small for sch 40 material. As I'm unfamiliar with the machine you have I don't really know if those settings would give you a short circuit or spray transfer. I'm going to hazard a guess though that you've got it up in spray transfer mode. So what could be happening with that small of diameter wire is that you're over driving it and running it way to hot. Not "to hot" from the standpoint of it burning thru your material but rather "to hot" from the standpoint of it over heating the puddle to where you're vaporizing out to much of the deoxidizers (silicon and manganese) in the wire. If your base material is made from a killed steel that's had some aluminum added to it I can see that aluminum getting vaporized out of an over heated puddle being the culprit for the black soot (smut). Are you pushing or pulling your puddle when you weld? And does doing one or the other make any difference in how much black soot is left on the weld?
Reply:Concerning mill scale and mig welding.... that thin, tightly adhered mill scale like would be found on 14 ga. HRS and square tube .....well, I mig weld over it all the time with out problem. I'm normally using 70S-6 wire (.030 to .045 diameters) and C25. Can't remember the last time I ever used 70S-3 wire so don't know if that might be a significant factor in why I seem to be able to get a way with doing that with out any problems. Since you're using a flapper disc to remove paint before welding the paint dust left over from doing that could be the thing that's causing that black soot if it's getting in the weld. Also just the oxide particles that come off the flapper disc could be causing the problem. I like keeping an air nozzle handy to blow things off before welding. Also if you're making a lot of that kind of dust from grinding (the chop saw is another source of it) in your work area it can settle out on the wire on the spool on the machine and then make it's way from there into the weld. So a good idea to eliminate that source of contamination is to always run a wire wiper and check it frequently for build up.
Reply:HT2-4956: Wow where to start. I will try bumping the flow a bit and see what happens. I am thinking now that my biggest problem, other than not knowing how to weld, is cleanliness of the weld surfaces. I have a wiper/lube on the wire prior to the wire feed rollers, maybe that is part of it too. The machine is set on 5, which the chart says is 100A and 19V. I have been playing with both Voltage and Wire Feed rate but have to be more rigorous with the test. I have been welding T-joints with the pipe and I can only get about an inch at a time before I am out of position again. Will go back to straight flat welds and see what happens. The wire came from usaweld if I remember correctly. I do notice that when I slow down the wire feed with the voltage tap on 5, I see small "balls" falling from the wire. If I then drop the tap to 4 without changing the feed rate the "balls" go away but harder to get the puddle to form. I think that the extent of the "smut" is not significant and may just be a product of the process. You have given me many good things to ponder. I will work through this and see what comes out in the end. Thank you for all the attention and good advice. Take care. Burt
Reply:Nobody else has mentioned this but what does the inside of the pipe look like. There could be oil/paint other stuff that comes out while doing the t joints.
Reply:mwshaw: Actually I have not paid any attention to the inside. I guess filthy would be the best description. Cutting oil primarily from notching with a hole saw. I guess it is not just the outside of the pipe that needs to be clean. More work to do the next time I try to put something together with tube or pipe. Thanks for the insight. Take care. Burt |
|
发表于 2021-8-31 22:20:35