4. Conclusions
The influence of temperature on hardness and three body
abrasive wear of boron steel and two different tool steels has been
studied. The main conclusions from this work are as follows:
An increase in temperature results in reduced hardness for all
the investigated materials. This relationship is not linear, a
higher reduction rate is found above 600°C.
The wear behaviour is temperature dependant. The main wear
mechanisms vary for each material and range of temperatures.
In general, a transition from microploughing to a combination
of microcutting and microploughing has been observed. At
elevated temperatures (from 400 to 800°C) the wear rate
increases for all the tested materials mainly due to recrystallization of ferrite grains at the outermost surface of the samples.
Toolox
44
displays a stable wear rate from 20 to 400°C. This is
mainly due to the almost unchanged hardness in this range of
temperatures.
Even though Toolox
44
displays the highest hardness in the
whole range of testing temperatures, its wear resistance did
not show a significant improvement compared to Toolox
33
especially above 100°C.
Toolox
33
shows lower wear rates between 100 and 400°C
compared to 20°C and this is mainly attributed to an increase
in its toughness in this range of temperatures.
Boron steel shows a decrease in wear rate from 20 to 100°C.
This behaviour is characterized by the formation of a tribolayer
Workhardened
layer
Fig. 13.SEM micrographs of boron steel at (a) 20°C and (b) 100°C.
Fig. 14.SEM micrographs of boron steel tested at 600°C showing the presence of (a) a fragmented silica particle and (b) recrystallized ferrite grains at the surface.
S. Hernandez et al. / Wear 338-339 (2015) 27–35 34
consisting of plastically deformed material and embedded
particles at the outermost surface of the specimens. At higher
temperatures however, this phenomenon is outweighed by
recovery and recrystallization processes.
Acknowledgements
This work was funded by the Austrian COMET-Program (Project
K2 XTribology, Grant no. 824187/849109), and has been carried out
within the Excellence Centre of Tribology and Lulea University of
Technology (LTU). The authors gratefully acknowledge the support
and resources provided by these organizations