D2 tool steel is a cold work die steel with some very attractive properties when it comes to bladesmithing. The typical elemental analysis is as follows: Carbon 1.50; Manganese .40; Silicon .40; Chromium 12.00; Vanadium .95; and Molybdenum .90. It is has excellent wear and abrasion resistance, high dimensional stability, and exceptional edge-holding ability. It is an air-hardening steel that is most commonly seen used in industrial shear knives, chipper blades, cold forming dies, punches, slitter knives, knurls, and burnishing tools.
I have been using D2 for over 12 years now and my experience has shown it to make some very exceptional blades. It has superb edge retention, very respectable toughness and decent corrosion resistance. It is a stain resistant steel as opposed to being stainless. Stainless steels typically have at least 14 percent chromium and often as much as 18 to 22 percent. The presence of molybdenum and vanadium increase the response to heat-treating, increase the wear resistance and the toughness. I have found D2 to hold an edge exceptionally well and a properly forged and heat-treated blade of D2 can easily slice through sheet metal, steel lumber banding, and curl the edge from a competitor’s knife with ease not to mention gliding through paper, cardboard, leather, cloth –including kevlar- and other materials without hesitation. I have two daggers that I have been subjecting to all manner of use and abuse for the past 8 years. Both I forged from D2 tool steel. They have the modified flat grind also known as the Moran (Bill Moran) Edge. They have disjointed game from rabbit to black bear, butchered meat, chopped up seasoned hardwoods, sliced through steel lumber banding countless times, not to mention goodness knows how many literally hundreds of yards of cloth, cardboard, paper and leather. Their performance has outshone any other dagger of the same design but using a different steel.
D2, because of its air-hardening properties (meaning that it is not generally quenched in brine or oil during the heat-treating process), is a somewhat difficult steel to work. It is a bit red-hard due to the molybdenum content, so forging must be undertaken slowly, methodically, and carefully, always mindful of the narrow forging range. Too hot and the steel burns, not hot enough and the steel begins to harden and will likely shatter. Austenite forging, which is similar to edge-packing, is done at a lower temperature. D2 responds very well to austenite forging but even more care is necessary. The austenite forging creates a very refined grain structure resulting in a very hard edge. For a superior blade that requires a small amount of care, D2 is your choice.