This may lead to higher
volumes of carbide and, despite the fact
that M2 contains some MC type carbide
and only a limited amount of M23C6,
high volumes of chromium based carbides
might be expected to have an adverse effect
on the annealed hardness. A further issue
is the level of chromium in the alloys. In
the case of M2 most of the chromium
is precipitated in the form of carbide.
However, in the case of OB1 and D2 there
is an excess of chromium, some of which
will be in solution in the matrix, and this
will lead to higher matrix hardness.