ELECTRON MICROSCOPIC STUDY OF THE CONTACT ZONE SURFACE (HIGH-SPEED STEEL P2M9) ‒ SUBSTRATE (STEEL 30KHGSA)

One of the important problems of practical application of high-strength plasma surfacing of high-speed steels in a nitrogen environment is the analysis of the damping properties and adhesion of the surfacing and the substrate, since these properties largely determine the premature nucleation of brittle microcracks in the contact zone. Such results can be obtained only using highly informative methods of modern materials science, such as scanning and transmission electron microscopy. In the article, surfacing of tungsten-molybdenum steel P2M9 has recently found wide application instead of well-known tungsten (type P18, P9) and tungsten-molybdenum steels with increased tungsten content (type P6M5, P6F2K8M6, etc.). This is due to the need to replace expensive and scarce tungsten with molybdenum, which, being in the same group of the Periodic Table of Elements with W, has a similar effect on the structure and properties of high-speed steels. The structural-phase states, morphology and elemental composition of the transition zone of the contact of the system "deposited high-speed steel R2M9-substrate (steel 30KhGSA)" in the initial state and after triple high-temperature tempering were studied. In the initial state, the transition zone has a martensitic structure with layers of residual austenite along the boundaries of martensite plates. Particles of the second phase of the nanosized (2 ‒ 60 nm) range were revealed – vanadium, molybdenum, tungsten and iron carbides localized at dislocations, at the boundaries and in the volume of martensite plates. Triple high-temperature tempering does not change the morphology of the carbide phase particles of the transition zone. Possible physical causes of the observed patterns are discussed.