The process of hardening the surface of steel whilst leaving the
interior unchanged. Both carbon and alloy steels are suitable
for case-hardening providing their carbon content is low,
usually up to a maximum of 0.2%. Components subject to this
process, particularly in the case of alloy steels, have a hard,
wear-resistant surface with a tough core. A process in which the
surface (case) of the steel is hardened and the interior (core)
of the steel is left unchanged. A number of different techniques
are available for achieving this objective. Adding carbon to the
surface of iron-base alloys by absorption through heating the
metal at a temperature below its melting point in contact with
carbon material. The oldest method of surface hardening wrought
iron and other low-carbon steels by packing it in charcoal or
some other carbon-based material, then heating it for several
hours above 1650. The process of hardening the outer surface of
the steel only. Requires only a low carbon content (usually less
than 0.2%) to