HARDENING - Thermally induced hardening of metals that relies
on crystal structure change. Martensite is the name of the
hard room temperature crystal structure of steel.
Transformation to this structure is achieved via quenching.
Carbon and alloy steels, carburizing steels, tool steels and
400 series stainless steels all rely on this hardening
PRECIPITATION HARDENING -
Thermally induced hardening of metals that relies on
precipitation of solute in a solid solution of 2 or more
metals. Formation of precipitates hardens alloys such as 17-4
and 13-8 stainless, maraging steels, beryllium copper,
titanium alloys, inconels and hastelloys.
CARBON - The most
important alloying element in steel. Strength, hardness,
hardenability and ductile-to-brittle transition temperature
are increased with increasing carbon content up to
approximately .60%. Toughness and ductility are decreased
with increasing carbon content.
Resistance of metal to plastic deformation, usually by
indentation. However, this may also refer to stiffness or
temper, or to resistance to scratching, abrasion, or cutting.