Effect of forming temperature and step-controlled heating Forming process on the microstructure and properties of vacuum powder-forged WC-12Co cemented carbide

This study investigates the effects of a step-controlled heating forming process on the microstructure and mechanical properties of vacuum powder-forged nanocrystalline WC-12Co cemented carbide. Comparative experiments were conducted between direct heating and step-controlled heating processes at different forming temperatures (1250 °C, 1300 °C, and 1350 °C), systematically analyzing variations in density, hardness, flexural strength, and fracture toughness. The results demonstrated that at 1300 °C, the step-controlled heating process, by reducing heating rates and incorporating staged holding, effectively suppressed abnormal WC grain growth and promoted homogeneous co-phase distribution. This led to superior material properties, including higher density, flexural strength, and fracture toughness, compared to specimens prepared via direct heating. However, at 1350 °C, the mechanical properties of step-controlled heating specimens significantly deteriorated due to abnormal WC grain coarsening and Co phase depletion. The study confirmed that the step-controlled heating process optimizes holding time during the solid-phase sintering stage, enabling the fabrication of cemented carbide at lower temperatures (reduced by 50 - 100 °C) while achieving enhanced densification and microstructural homogeneity. This work provides a novel approach for manufacturing high-performance cemented carbide tools with improved energy efficiency and reliability.