STRUCTURE AND MICROHARDNESS OF TITANIUM ALLOYS AFTER ELECTROMECHANICAL TREATMENT AND ULTRASONIC SURFACE ALLOYING

The authors proposed the complex technology of surface hardening
of titanium alloys based on a combination of surface alloying with
boron and carbon, electromechanical treatment (EMT) and non-abrasive ultrasonic fi nishing (NUF). The results of the study of microhardness and features of the structural-phase state of the surface layer of 5V titanium pseudo-α-type alloy were presented after various combinations of treatments (EMT, NUF, surface alloying). It was shown that for a variety of schemes hardening was achieved by increasing the surface microhardness of the treated material to 30 – 40 %. The greatest effect can be observed when using alloying agent during EMT + NUF (graphite cast powder in combination with an organic binder). Increase in microhardness was provided due to the hardening by severe plastic deformation of the metal, grain size refi nement (from 50 to 1 μm) during phase transitions, as well as the formation of fi ne reinforcing  borides and carbides of titanium (whose content in the surface layer increased up to 1.88 and 0.46 %, respectively).

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