by Larry Connelley
D2 steel's popular use began during World War II. D2 steel was used to make dies for production lines. A die is pressed down to cut and create shapes out of softer steel. The original, and still most common, use of D2 steel was not just cutting other steel by pressing down, but doing it over and over and over in a factory. Through modern knife history, many high-end knife steels (specifically 154CM) were adapted indirectly because of the steel innovation in the tool and die industry.
This work history enables us to determine the strengths of D2 knife steel. Most importantly, D2 steel is hard. D2 steel has an air-hardened, high-carbon, and very high-chromium composition which creates this high-end knife steel with a hardness in the range of 55 to 62 HRC. Chromium-rich alloy carbides create excellent resistance to wear from sliding contact with other metal or abrasive materials. This steel has a high wear resistance and creates a tough knife that holds an edge. The very high chromium content provides better corrosion resistance than most tool steels and enables it to be semi-stainless.
Many steel companies make their own D2 steel but the composition stay very close to the norms - the alloy composition of D2 blade steel provides a guidebook to its unique qualities:
Carbon (C) 1.50 to 1.68 percent: Contributes to hardness, to holding an edge, to tensile strength, and to resistance to wear.
Chromium (Cr) 11.50 to 12.00 percent: Contributes to strength and wear resistance, also, to resistance to corrosion. Stainless steel contains 13 percent chromium.
Molybdenum (Mo) .60 to .90 percent: Contributes to machinability, resistance to corrosion, and strength at high temperatures.
Vanadium (V) .90 to 1.10 percent: Refines the grain, contributes to toughness and edge stability.
Manganese (Mn) .15 to .45 percent: Contributes to strength, wear resistance, and grain structure.
Silicon (Si) .10 to .40 percent: Contributes to strength.
Phosphorus (P) .03 percent: in very small amounts increases strength and hardness.
Sulfur (S) .03 percent: Increases machinability.
Iron (Fe) is balance of the steel's composition.
The strength, hardness, and wear resistance that allowed D2 steel to contribute to the United State's massive production for the war effort in the 1940s; produces a unique, strong knife today.
Some notable knife companies that utilize D2 steel are Brous Blades, Lion Steel Knives, KnifeArt Knives and various other high-end knife manufacturers.