(electrones = electrodes) Today I experimented with my DC welder using a copper crucible. The latter is a cylindrical casting of 2" diameter and 1 1/2" high with a hemispherical cavity in it. There I put pieces of steel to be melted. I got this idea that some commercial lab furnaces have this principle: using a copper crucible for melting metals with a much higher melting point, up till tungsten. The reason is that Cu is a very good heat conductor. And for me I pefer it over graphite to prevent steel contamination with carbon. And yet, as I still use a carbon cathode the steel melt can also absorb C from the electrode. So I tried using a steel cathode but I noticed that the arc is not sustainable and the steel rod sticks (and even welds) to the steel to be melted. I reversed the electrodes: used the copper cup as a cathode and the steel rod as an anode, but to no avail, still sticking and an unsustainable arc. I tried blowing argon gas over it to prevent oxidation, but to no avail as well. Why does carbon sustain the arc and steel not ? And can I use tungsten cathode / anode ? Because W is used in TIG welding as electrode. (Otherwise the steel industry would use steel electrodes in their EAFs ?)
We had a sample furnace at work that used a copper crucible, Argon gas and a tungsten electrode. I think the base was a 400 amp Miller welder. We would melt samples of lathe turnings and other scrap, checking for high chrome or Sulphur. The only problem we ever had was a college intern decided to melt some Vanadium in it. The electrode stuck and the metal stuck to the crucible. We had a hard time getting it apart to fix it.
I tried melting other metals and it did: Ferrochrome (70% Cr) and Titanium. It did not stick to the copper and I blowed argon gas on the arc + metal to prevent oxidation. Ti metal cannot be melted in open air. But still using a carbon cathode. And the copper 'cup' soaked rather much heat from the metal pool.
I offer some thoughts, with the qualification that I have never melted steel, never used a copper crucible, or melted metal with an electric arc. I only melt bronze in an oil fired furnace. I have done a good bit of welding, some stick welding, but mostly gas welding of aluminum and stainless sheet metal. My gas welding is professional quality but, after ten years, my stick welding still looks like it was done by a five-year-old. So to go on with my idea. In electric welding, gouging rods are sometimes used to burn holes in steel. They are made of graphite.( I use them, but only as sheaths for my thermocouples.) They don't deposit anything; they burn holes. Stick welding rods are steel. They deposit metal on the other side of the arc. It seems to me that trying to use a steel rod to produce an arc without moving the rod continuously as you do when welding, you would build up molten steel on the other side of the arc and pretty quickly bridge the gap between the rod and the other conductor, thus stopping the arc. Richard
Indeed, you talk about gas welding which probably means TIG welding, using inert gas (usually Argon and CO2 or sometimes pure Ar) flowing over the arc. That is indeed often used for stainless steel or aluminum. And that (I have never done that) should work flawlessly. But you are right that building up the steel on the other side sticks to the steel rod which breaks the arc. I tried with blowing Ar over it or putting some silica sand / lime mixture flux, but to no avail.
I have some solid tungsten 1/4" in diameter, and some tungsten iron bars 1" in diameter. You'd have t shield them from the air, but the should be easily able to handle the current. The local foundry uses electric arc furnaces for their 20 ton steel and stainless melts. I think those electrodes are water cooled though.
