JURČI Peter Slovak University of Technology in Bratislava

Spoluautoři DOMÁNKOVÁ Mária, PTAČINOVÁ Jana

The microstructure, with a particular focus on carbides, of Cr-V ledeburitic steel Vanadis 6 has been examined in various stages (soft-annealing, quenching, sub-zero treatment, tempering) of the heat treatment process. The characterization of the carbides was done using the scanning electron microscopy, transmission electron microscopy and X-ray diffraction. The obtained results show that as-annealed material contains the MC- and the M7C3-carbides, respectively. The M7C3-phase forms the eutectoidal and secondary carbides while the MC-phase is of the eutectic nature. During the austenitizing, a significant amount of the M7C3-phase underwent dissolution while the MC-phase remained unaffected. Moreover, small amount of cementite was identified in as-quenched material, in the form of small globular particles with a size of around 100 nm. The sub-zero treatment does not alter the nature of the carbides, compared to that resulted from conventional quenching, but only their volume fraction. It increases moderately due to the sub-zero treatment. The tempering of the steel to secondary hardening peak leads to a formation of fine carbides, which are mostly of two types – the cementite and the M7C3, respectively.