Sentry Diamond Blocks are
removable inner furnace linings composed of a carbonaceous material. At steel
hardening temperatures they are slowly consumed, generating a protective
gaseous atmosphere. When used for hardening tool steels, the atmosphere generated
prevents harmful oxidizing effects including scale and decarburization. Useful
for producing quality hardening, Diamond Block applications include intermittent
and production hardening of all types of tool steels.
Among their most desirable features, Diamond Blocks are simple to use. The
atmosphere generated is maintained constantly correct without requiring the
continual analysis or regulation associated with other generated furnace atmospheres.
The process is clean and does not employ chemically active materials which
attack furnace parts or produce other harmful effects.
Here's how it works! Atmospheres
are developed primarily to prevent oxidation and decarburization of the steel
surface during heat treating. Oxidation, commonly called scaling is directly
related to decarburization. Decarburization is the loss of carbon from the
surface of steel and results in a soft surface where a hard surface is desired.
When air is presented in a hardening furnace, the oxygen combines with the
steel and produces a scaled surface. An air atmosphere can be enriched with
various forms of carbon to limit undesirable scaling until a point is reached
where the scale completely disappears. However, an abrupt change sometimes
occurs at this point so that instead of the tools being scaled they are badly
decarburized. Further enrichment of the atmosphere decreases the amount of
decarburization until it finally disappears. A neutral point is reached where
the steel is neither giving up nor absorbing carbon. This neutral point, which
is ideal for hardening tool steels, is automatically produced by the Sentry
Diamond Block.
Tools hardened by the Diamond Block method retain their initial sharp, clean-cut
edges with no scale, decarburization or reduction in size. Maximum surface
hardness is obtained and finishing operations are reduced or eliminated. Without
oxidation, tools will not overheat in the furnace and it is safe to allow for
ample hardening time to achieve maximum hardness and proper grain structure.
Tools hardened by the Diamond Block method will give maximum useful service.
Click here for detailed information on the use of Sentry
Diamond Blocks.
