D2 (1.2379) is a staple of the tool steel industry, having been with us for many years. It is one of the most well-known and popular grades of tool steel due to its high levels of wear resistance and toughness resulting from a high volume of hard carbides (carbon & chromium) in the structure of the steel. Other key properties include particularly good dimensional stability and high compressive strength. D2 comes under the Air Hardening sub-category of Cold Work Steels and its composition and properties are close to stainless steel.
If you need an edge that will stay sharp for a long time, and to avoid tool failure by breaking, chipping, cracking or premature wear, D2 will likely serve you well.
D2 is mainly used for tools where there is severe wear and abrasion: press tools, cutting, punching, stamping, knurling tools, blanking tools, crushers, shear blades, thread rolling dies, cold extrusion dies, deep drawing and bending tools, flanging and straightening rolls, fine cutting tools, plastic moulds for abrasive polymers.