Microstructure and mechanical properties of zinc recycled tool grade cemented carbide inserts

Abstract

A production run of mixed carbide inserts was scrapped. These inserts were zinc recycled and approximately 70% metal recovery was achieved, while 30% was Co-rich oversized particles. The recovered powder was divided into two batches with one adjusted for C and the second for C and Co. The powders were used to produce sintered compacts, and the properties were benchmarked against compacts produced from the original powder. Acceptable shrinkage with comparable densities and low porosities were achieved for all. Cubic-free surface layers (CFL) formed in all alloys with a narrower layer in the recycled alloys. Although the carbide grain structure differed between the alloys, the TaC and NbC restricted grain growth effectively. A linear inverse relationship was found between Co in the CFL and Ti immediately beneath the CFL for all alloys. Similar magnetic, hardness, fracture toughness and slurry abrasion properties were measured with some deviations for the higher Co alloy.

Original article: J. Kurasha, N. Sacks, C. Freemantle, first published in the EURO PM2025 Congress Proceedings. © EPMA – European Powder Metallurgy Association.