Generally the lifetime of tools is affected
by their hardness and wear-resistance. But additional characteristics
like dimensional accuracy and a low degree of residual stress
are as well indispensable preconditions for faultless functioning.
Micro-structural changes, like retained austenite transformation
during the use, can cause early rejections which should
be avoided.
Retained austenite is termed to be the
part of austenite which remains in the microstructure after
quenching to room temperature. Under some circumstances,
especially with high alloyed tool steels, the retained austenite
can have significant influence on the quality and usability
of the material.
The targeted transformation of retained
austenite by combining conventional heat treatment technology
with deep freezing is in most cases the most suggestive
solution in matters of technology and economics in order
to achieve the predetermined material properties.
|