Introduction to Cemented Carbide Pick Teeth

Introduction to Cemented Carbide Pick Teeth

Cemented carbide pick teeth, also called cemented carbide coal pick teeth, are made by brazing cemented carbide ball teeth with alloy structural steel. They are cutting tools used with coal mining machines and other engineering machinery, featuring excellent thermodynamic and chemical properties, specifically high hardness, high strength, good wear resistance, excellent high-temperature performance, and superior corrosion resistance.

During coal seam mining, cemented carbide pick teeth rely on impact rotation to perform cutting operations, needing to withstand cyclic alternating compressive stress and shear-bending stress. During excavation, the pick teeth also experience intense friction with the coal seam, generating frictional heat. Additionally, throughout the mining and excavation process, the pick teeth may experience localized yielding, contact fatigue, corrosion, and fracture, among other failure modes.

It is worth noting that during coal seam excavation, cemented carbide pick teeth often experience tooth head chipping under impact loads. This is mainly due to the uncertain geological conditions of the coal seam, which prevent the tooth head from fully conforming to the coal seam, while impurities such as gangue in the seam further exacerbate poor contact at the tooth head. Under continuous alternating loads, the pick teeth are prone to developing impact fatigue cracks and thermal fatigue cracks, ultimately leading to failure.

To improve the failure performance of cemented carbide pick teeth, the alloy’s grain size, composition, and ratio can be adjusted to enhance its performance. Specifically, the cobalt content in the alloy can be appropriately controlled at 8%–13%, as cobalt effectively improves the alloy's thermal fatigue resistance, plasticity, and helps relieve stress. Suitable tungsten carbide (WC) powder grain size and ratio can also be chosen: generally, the smaller the WC powder particle size, the larger the surface area, which can increase the average free path of cobalt, effectively equivalent to increasing cobalt content, benefiting the improvement of alloy toughness. Additionally, to enhance the role of the cobalt phase, proper heat treatment can be applied to the pick teeth.