Influence of deep-cryogenic treatment on wear resistance of vacuum heat-treated HSS

In this paper we compare the wear behaviour of a vacuum heat-treated ESR AISI M2 high-speed steel and the same steel that was vacuum heat treated in conjunction with a deep-cryogenic treatment at −196 °C. Four different tempering temperatures for the specimens austenized at the same austenitizing temperature were carefully selected to obtain various in-advance-determined combinations of the Rockwell-C hardness and the fracture toughness K_Ic. Each of the eight specimens was therefore characterised by these two resulting material properties. The wear behaviours were then compared and discussed in terms of these two properties and the related microstructures. The differences in the wear resistance obtained in our investigation were as high as an order of magnitude. However, the beneficial effects are not a direct result of the type of the treatment, but relate to a proper combination of the resulting fracture toughness and the hardness. The more uniform and moderate (but sufficiently high) values, which tend to be obtained with a deep-cryogenic treatment, are beneficial to the high wear resistance of the selected high-speed steel.