A concept for deep cryogenic treatment of tool steels

Abstract

A short review of experimental data about the effect of deep cryogenic treatment,
DCT, on the abrasive wear of tool steels is presented along with available hypotheses. Using
Mössbauer spectroscopy, X-ray diffraction, mechanical spectroscopy and transmission electron
microscopy, it is shown that the isothermal martensitic transformation proceeds in the course of
DCT. Moreover, the softness of the virgin isothermal martensite initiates the plastic deformation
during martensitic deformation, which results in the partial removal of carbon atoms from the solid
solution by the gliding dislocations. This effect eliminates the precipitation of the ε(η)-carbide
during subsequent tempering, shifts cementite precipitation towards higher temperatures and
delays precipitation of special carbides at temperatures of secondary hardness. Thus, the
precipitation potential of the γ solid solution is preserved and can be realized during the usage of
tools increasing thereby the tools life. Based on the obtained results, a new concept of DCT is
developed and the correction of its technology to the temperature range of the isothermal
martensitic transformation is proposed.