Century Drill and Tool 4424 Cobalt Bi-hard Hacksaw Blade, 12-Inch by 24T Cobalt Bi-Hard hacksaw blades offer a unique design that stays cooler and remains sharper while cutting harder materials like steel or hard metals One piece construction cannot edge strip and avoids any of the weld line problems associated with bi-metal blades Century's stages heat treated process creates the strongest teeth while the backbone is heat treated to a lower degree enabling its flexibility