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I'm interested in knowing whether or not submerged welding can be done in fluids other than water, specifically mineral oil in this case. The reason I want to know is that I'm looking into designing an extrusion 3D printer for metals that works on the same principle as stick welding, like these ones:

https://hackaday.com/2020/03/31/3d-metal-printer-uses-welding-wire/

https://3dprint.com/226829/researchers-develop-low-cost-metal-3d-printer/

However, I don't want the metal to oxidize, and the machines in these examples produced very poor surface quality due to the metal overheating and melting. I know that the oxidization could be prevented by surrounding the entire print in an inert gas, like argon, carbon dioxide, or sulfur hexafluoride, but I wanted something that would be easier to recycle without getting contaminated, plus a fluid would help to keep the print cool. Water isn't an option because it rusts metal and its conductivity makes it dangerous to use with electricity, so mineral oil seemed like the best option, as it is also used to cool transformers.

My major concern with using oils of this kind is, obviously, that they are flammable when heated to high temperatures in the presence of oxygen, so for this question I'm assuming the welding is taking place either in an airtight box (but expandable to account for the oil evaporating), or in a swimming pool full of mineral oil big enough for the heat to dissipate into safely. I was also wondering if the oil might decompose into toxic chemicals at welding temperatures or introduce unwanted inclusions or contaminants into the weld. Anything you can tell me would be helpful. Thanks.

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  • $\begingroup$ After watching the videos of the MIG, I wonder what use a lump of weld metal with questionable properties would be other than a doorstop ? $\endgroup$ – blacksmith37 Jul 11 at 19:29
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No. In water welding you make steam (> hydrogen and oxygen) and conditions need to compensate for the problem of hydrogen entry in the steel. With oil you are adding the large problem of also adding carbon to the steel. Plus the oil will be cracking and producing a whole range of smaller molecules and probably some carbon and very heavy tar-like materials.I never heard of anyone trying to do it so it is hard to imagine what might be produced. On the other-hand glove-box and gas ( argon and helium only) etc. shielded welding of titanium is routine well established,old technology.

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  • $\begingroup$ That tells me what I need to know. Thanks. : ) $\endgroup$ – Gabe Jul 13 at 2:08
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Mineral oil is not used to cool transformers because it is flammable. Transformer oil is a different compound which is not flammable and possesses high dielectric strength. In any case, the temperatures inside a welding arc are high enough to decompose almost all chemical compounds, as Blacksmith37 points out.

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  • $\begingroup$ will edit. -Niels $\endgroup$ – niels nielsen Jul 20 at 20:46

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