My dad found an old cutting edge from one of their large landscaping machines at work. it was one inch thick, one foot wide, and three feet long. I managed to cut it into three one square foot plates that I am working on to laminate together into the block that I need. As a cutting edge it is all hardened steel, and the plasma cutter had a lot of trouble cutting the one inch plate. Only my brand new cobalt drill bits were able to drill through it so I could bolt them together before welding them around the perimeters as well as a few plug welds. I don't know if a mill bit could cut this steel easy enough to shape it if it isn't annealed some how. Perhaps it could be softened a bit after I weld the p-lates and leave them to cool slowly, because neither my oven nor my forge are big enough to hold them.
