High-Speed Steel Technology Substitution in Mining Machinery – an Experimental Study

mineral resource sector under conditions of external restrictions
requires the modernization of the domestic mining machinery – an
indispensable condition of which is the replacement of technologies
for the production of high-speed steels and machine tools. This
research was aimed at experimental studies of microstructure, phase
composition and microhardness distribution in the surface layer of
the R6M5 high-speed steel samples after laser cutting, cold treatment
and laser tempering. It was demonstrated that after laser cutting in the
surface layer of the cut there was the carbide dissolution and
enrichment of the metal matrix with carbon and alloying components,
resulting in an increase of residual austenite content up to 50...60 %.
After the cold treatment in liquid nitrogen the content of residual
austenite decreased up to 7...9 %. The laser cut surface microhardness
increased up to 1000...1100 MPa. At further laser tempering the
dispersion hardening processes took place, as a result the V2C
carbides appeared in the steel structure amounting to 4.7 %. The
microhardness increased up to 10400...10600 MPa. The study
showed the possibility of using the high-speed steel laser cutting not
only as a separating operation, but also as a hardening treatment. The
findings contribute to the technological support for the development
of domestic mining machinery in terms of replacing imported highspeed steels and machine tools.