Operational properties and local wear mechanisms of hard alloys alloyed by tungsten nano carbide under turning
Journal Title: Вісник Тернопільського національного технічного університету - Year 2015, Vol 79, Issue 3
Abstract
Operational properties of the titanium carbide based hard alloys alloyed by vanadium carbide (5% (wt.) and tungsten nano carbide (5, 10, 15% (wt.) with nickel-chromium binder (18% (wt.) under turning were researched in the paper. The processing of construction carbon and alloyed steels under shoulder and facing turning by inserts made of developed alloys was carried out. The tool life at semi- finishing and finishing turning operations was identified and the critical (maximum) cutting speed at which the critical inserts wear takes place was determined. It was shown that the application of tungsten nano carbide results in the increase of cutting tools wear resistance as the alloys with nano WC tool life is 109…154 min and exceeds that of conventional carbide based hard alloys, tungsten-free hard alloys and polycarbide based alloys alloyed with fine-grained tungsten carbide. The critical cutting speed the alloy with 5% (wt.) nano WC is 830 m/min and for the one with 15% (wt.) is 980 m/min. The features of local wear of alloys alloyed by tungsten nano carbide were studied taking advantage of the electronic microscopy and chemical analysis methods. The analysis of the wear zone showed that it consists of two areas, the tribolayer, containing a significant amount of oxygen and the elements of instrumental and processed materials, and abrasive wear area. It was determined that the abrasion wear is the main local wear mechanism of researched alloys. The main features of demage in the area of abrasive wear are large carbide grains cracking, their parts removal and small carbide grains splintering. Availability of tribolayer on the back surface of the cutting edge changes the temperature and force conditions of the tool material cutting and demage that occurs as a result of oxidation and diffusion interaction with the elements of the processed material.
Authors and Affiliations
Sergiy Marynenko, Ihor Koval, Lyudmyla Bodrova, Halyna Kramar
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