Check your local scrap yard and see if they have some 1" or bigger crane cable, that stuff works pretty well, make sure you have big wires to start out with. Forge welding anything smaller than 3/4" wont leave you with enough carbon to hold a good edge. Get yourself some anhydrous borax for flux, much better then regular borax and remember to flux then tighten the cable by twisting it. Befor you start, unravel a small part of the cable and remove a strand, then quench it to see if its hardenable ( not all steel cable is high carbon ), also make sure theres no foreign objects like rope or plastic in the center of the cable, if there is make sure you take it out. Good luck! Its fun stuff to work with