Glenn Posted July 22, 2006 Share Posted July 22, 2006 From the email: What is the purpose of flux during forge welding, I mean what does it do exactly? Can other things be used instead of borax? Quote Link to comment Share on other sites More sharing options...
HWooldridge Posted July 22, 2006 Share Posted July 22, 2006 From what I can determine, flux prevents/minimizes the normal formation of oxides (scale) that develop in the high heat of the forge and helps float away impurities that may be present. The intent of a forge weld is to put two clean pieces of iron or steel together under heat and pressure to form the bond - but interference from contamination can prevent that from occurring. Good wrought iron can often be welded without flux because the scale is molten enough to push aside. This is harder to do with steel because the proper welding temp is lower and the scale clings to the surfaces to be welded. The Japanese were doing some R&D a few years ago with "forge welding" at room temps with chemically clean samples in an oxygen-free environment, using large hydraulic presses to generate the pressure. The metals would bond at the molecular level because there was nothing to interfere. Quote Link to comment Share on other sites More sharing options...
irnsrgn Posted July 22, 2006 Share Posted July 22, 2006 Flux is a liquid seal when hot to prevent the metal from oxidizing, most people put way to much on. A light coating is all that is necessary and then hold it over the fire till it melts completely before putting back in the fire. There are other prepared and made up fluxes, but they are borax based. Quote Link to comment Share on other sites More sharing options...
ThomasPowers Posted July 24, 2006 Share Posted July 24, 2006 Flux works in several ways: one is to keep O2 away from the metal; another is to help liquify the scale that has formed. Wrought Iron was pretty well self fluxing from the metal silicates in it and from the higher temperature you worked it at. Traditionaly if you needed more flux you used clean quartz sand or even ground glass. IIRC Foxfire even mentioned the use of dirt dauber nests. Japanese swordmakers used rice straw ash and wood ash has been used by the "primal smiths" If you are working high alloy metals you often need a more aggressive flux to deal with the Ni and Cr oxides and pattern welders often add a bit of flourspar to their flux mix though the fumes are more toxic then. If you are really into how forge welding works "Solid Phase Welding of Metals" by Tylecote will scratch that itch. Quote Link to comment Share on other sites More sharing options...
B. Norris Posted July 24, 2006 Share Posted July 24, 2006 I do not know this for fact but, I've heard there is a bladesmith in South Africa who does all of his pattern welding without flux. All surfaces must be completely flat and sanded to 600 grit. Sounds like a real hassle to me! Quote Link to comment Share on other sites More sharing options...
Tyler Murch Posted July 24, 2006 Share Posted July 24, 2006 I know a bladesmith here in Macon that doesn't use any flux for his damascus. First he welds the edges so that the middle can't oxidize, then he welds down the middle. Quote Link to comment Share on other sites More sharing options...
julian Posted July 25, 2006 Share Posted July 25, 2006 I'm assuming theres an opening in the end of the billet, not sure why he would do the edges before the middle (wouldnt it scale anyway? or would it burn off all the o2?). but if it works as good as any other way why not. blacksmiths use flux for getting rid of spilled laundry soap and to keep a weld from oxidizing. Quote Link to comment Share on other sites More sharing options...
lefthand forge Posted July 25, 2006 Share Posted July 25, 2006 Julian, unless I miss my guess Tyler meant that the fellow " Arc welds" the edges before putting the billet in the forge, so no air can enter. But I could be wrong. Hope this helps John Quote Link to comment Share on other sites More sharing options...
mike-hr Posted July 25, 2006 Share Posted July 25, 2006 Flux should be used as a tool, not a crutch. If I'm at a hammer-in or public demo outside in the sun, flux will give an extra couple seconds of 'welding window', or help forgive a shallow or oxidizing coal fire. My shop forge is in a fairly dark corner where I can see what's happening. I try not to use flux if I don't have to. I went to a workshop several years ago, we did the 'water leaf' from the COSIRA book. It involved welding a sheet metal leaf to a length of 3/8" square. We used straight mule borax, and it worked good. The downside is, I found the piece on a shelf last week, and the weld has been precipitating white borax crystals. I need to find out how to pickle out the borax for fancy pieces I want to sell. I've made 10-15 cablemascus blades, a chainsaw chain letter opener, and half a dozen billets from L-6 saw blade, strap banding, and rasps, all without flux, and wired or hoseclamped together. The trick is a clean deep fire, Knowing where the non-oxidizing layer of the fire is, slow heats, and practice. I turn the radio off so I can hear if the fire is roaring or choked up. This is with a coal or coke fire, I've never been able to stick a weld in the gas forge.. The California BS Assoc. is lucky to have Mark Asprey as a very active demonstrator and instructor. He went through the apprentice system in the U.K., and now lives in central CA. He's brought in British Masters Adrian Legge, Richard Bent, and Mark Constable for workshops and hammer-ins. (See BP0222, split cleft weld). I haven't seen any of these folks use flux with wrought or mild steel. I'm not a very good welder, and rarely miss an opportunity to mess up a drop tong weld, especially in public. I just felt obliged to say that it's entirely possible to weld without flux, and folks shouldn't tell themselves they can't. Quote Link to comment Share on other sites More sharing options...
JPH Posted July 25, 2006 Share Posted July 25, 2006 Hello: I have been sitting by reading this and well...I have got to say something about flux... Yes, you most certainly CAN weld without flux...just like you CAN walk from Los Angeles to Bangor..Flux does a lot of different things...it does make it easier, but you still must do "your part" and do that correctly. 1: It helps protect from oxygen and other atmospheric "problems"..it does this by encasing the surfaces. 2: It can actually clean the surface by chemical action at temperature...This is why you will need a more "aggressive" flux than plain borax when you start to get into the higher alloy materials with elements like Mo, T, V, Cr and Ni. My "steel glue" flux was develouped over the span of close to 15 years' worth of experimentation..it does allow me to weld some pretty high alloy steels with little problems... 3: Flux will not "cure or improve" bad welding techniques. A bad weld is usually the results of the following: Improper tempertaure and not having a "clean" surface. Improper temperature is the most common and the easiest to correct. The clean surface..there is a lot "going on" in a welding fire...a flux will protect as well as help keep surfaces clean, both very important in a weld. No, fluxes will not "save you from yourself"..but it can help you keep things as clean as they can..and that will help get a good weld, IF you do your part... Now I don't claim to be no "master this or that"..(except for being good at putting worms on hooks...heh heh heh) but I know what works and why, and I have done a whole lot of welding over the years on some pretty wild stuff.. Fluxes do help...but they will not do it for you.. JPH 3: Quote Link to comment Share on other sites More sharing options...
Tyler Murch Posted July 28, 2006 Share Posted July 28, 2006 Julian, unless I miss my guess Tyler meant that the fellow " Arc welds" the edges before putting the billet in the forge, so no air can enter. But I could be wrong. Hope this helps John No, he forge welds the edges. Julian, he forge welds the ends shut too. Quote Link to comment Share on other sites More sharing options...
Bruce Beamish Posted August 3, 2006 Share Posted August 3, 2006 If all the edges are sealed (welded shut) there would be very little free oxygen in the centre of the layers to form scale and I suggest that these areas would still weld ok up at the correct temperature and pressure. I'm thinking along the lines of a steel ingot with a hollow sealed cavity or void in it will weld up during subsequent forging or rolling (if I remember my basic metallurgy studies correctly). Cheers, Bruce. Quote Link to comment Share on other sites More sharing options...
element Posted December 25, 2008 Share Posted December 25, 2008 The trick is a clean deep fire, Knowing where the non-oxidizing layer of the fire is, slow heats, and practice. I turn the radio off so I can hear if the fire is roaring or choked up. This is with a coal or coke fire, I've never been able to stick a weld in the gas forge.. Mike i like how you put it in the above copy pasted lines i took from your post. I have a question though, Were is the non-oxidizing layer? Quote Link to comment Share on other sites More sharing options...
Mark Aspery Posted December 25, 2008 Share Posted December 25, 2008 If you are really into how forge welding works "Solid Phase Welding of Metals" by Tylecote will scratch that itch. Thomas, Can you tell me a little more bout this book please. How much does it delve into non ferrous vs ferrous welding. I presume it covers friction and pressure welding... :confused: Quote Link to comment Share on other sites More sharing options...
Dave English Posted December 25, 2008 Share Posted December 25, 2008 On my first weld I used took some grinding spatter pile from a bench grinder that had metal and sand, sprinkled it on the flowing metal and borax on both sides of the work and tapped it together. It held just fine, but it was an experiment based on what I had read about using metal filings and/or borax glass or quartz sand, I just sort of improvised using what was available, but I didn't follow it up with more tests. Welding mild steel is more like glueing the metal together, the liquid surface providing the glue, and it's important for the newbies to not strike the metals together too hard, all the liquid will pop out and if it welds, probably be very weak. Quote Link to comment Share on other sites More sharing options...
Glenn Posted December 25, 2008 Author Share Posted December 25, 2008 I have a question though, Were is the non-oxidizing layer? Quote Link to comment Share on other sites More sharing options...
homesteader Posted January 3, 2009 Share Posted January 3, 2009 I have used battery acid to clean flux and then follow up with a water and baking soda bath. A commercial product called Sparex works pretty good also but is a little slower and more expensive. Make sure you have good ventilation for the acid fumes. Works for cleaning up flux on copper, brass and silver also. You don`t need as much time in the acid for the non ferrous metals. On the soda bath I usually mix a box of arm and hammer to two gallons of water. You can tell when the bath is wearing out as it quits fizzing from neutralizing the acid. Quote Link to comment Share on other sites More sharing options...
dimenickel Posted January 3, 2009 Share Posted January 3, 2009 purpose- lowers the melting point of iron oxide if the scale is included into the weld boundary... it would make for a weak weld Quote Link to comment Share on other sites More sharing options...
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