Welding steel cable requires a certain technique and skill in order to make it bond to another piece of metal or combine into a mass of metal, which will keep it from unraveling. The first thing to make sure is that you're actually welding fully steel cable and there is not rope or vinyl enmeshed between the wires, as this will burn and make a mess when you try and weld it. Once you are positive you are welding only high-carbon steel cable, you can begin the welding process.
Cut the steel cable to a workable length with a chop saw that has a metal cutting blade. Make sure it is cut to a length that will fit inside your gas forge. Then the steel cable must be cleaned. Use a solvent made of concentrated borax and water. Heat the cable and then dunk it in the water to clean it. Dry it and prepare to weld it.
Weld the ends of the steel cable first so that they bond together and don't come apart as you are welding the rest of the cable. Using your tongs, insert the end of the cable in the gas forge to heat it up. Once the end is nice and red, remove it and add flux, which is usually a Borax mixture that will help the steel cable strands to bond together properly in the forge. While it is impossible to add too much flux, sprinkle it on so that it doesn't create a mess. Do this with each end of the steel cable.
Once the ends of the steel cable have been heated up and fluxed, you can now weld the entire cable. Spread flux over the entire cable and put it into the gas forge with the tongs. Only heat up one half of the cut steel cable piece at a time. Heat it in the gas forge until it is red hot. Then remove the hot half of the steel cable and pound it with a hammer on top of an anvil, literally striking while the iron is hot. This will help to weld the steel cable together more solidly. It will be hard against each hammer hit if the iron has been heated up enough. If it hasn't, each hammer strike will feel a bit mushy.
Cool your tongs in a bucket of water. Use a wire brush to scrape off any of the scale or steel cable debris from the recently welded side. Now put the other half of the steel cable into the gas forge and repeat Step 3. Now the entire cable will be welded.
Twist the ends of the welded steel cable. Heat the entire welded cable up until it is red hot, flux it, heat it again and then use the tongs to place each end in a vice, pinching and twisting each end.