超硬合金の組織，特性，性能向上に関する技術開発

抄録

Since the invention of cemented carbide about 100 years ago, it has developed through extensive research in both its fundamental and applied fields. In recent years, the manufacturing industry has demanded higher productivity and efficiency, which requires further improvements in cemented carbides. This study began with the steel cord wire drawing dies, which are categorized as wear-resistant tools. It was found that the interface properties of WC significantly impact on the lifetime of steel cord wire drawing. In the wear of cemented carbide dies for steel cord wire drawing, HIP-processed alloys with TaNbC addition showed excellent performance, and further annealing treatment dramatically improved lifetime by a factor of about five. Moreover, ultrafine cemented carbide with fine particle Ti(C,N) additives, which improved interface properties, was found to have a significant effect on inhibiting the growth of WC grains by pinning WC particle surfaces with fine Ti(C,N) particles. Furthermore, ultrafine cemented carbide with a composite addition of fine Ti(C,N) and Cr₃C₂ achieved world-leading strength, recording an average transverse rupture strength of 4.6 GPa and a maximum strength of 5.0 GPa. Tests with this Ti(C,N)-Cr₃C₂ composite-added ultrafine cemented carbide on actual equipment showed results that outperformed conventional products in all cases.