The D series tool steels were developed
to take advantage of chromium both in
the form of carbides and heat treatability
of the alloy matrix. These materials
contain 12% chromium and only limited
amounts of the carbide formers tungsten,
molybdenum and vanadium. These limited
amounts reduce resistance to thermal
softening and limit the amount of carbide
present. The carbide types present are
predominantly M7C3, and M23C6.