Carbide pick, also known as carbide coal pick, is a cutting tool composed of carbide ball teeth brazed and alloy structural steel used in coal shearers and other engineering machinery. It has excellent thermodynamics and chemical properties. Properties such as high hardness, high strength, good wear resistance, good high temperature resistance and excellent corrosion resistance.
In the process of coal seam mining, cemented carbide picks perform cutting work in an impact-rotation manner, so they need to withstand high-pressure stress and shear bending stress at the same time. These stresses act periodically and alternately. During the excavation process, severe friction will occur between the pick and the coal seam, thereby generating frictional heat. In addition, during the entire excavation process, the pick may also undergo various mechanical behaviors such as local yielding, contact fatigue, corrosion, and fracture.
It is worth mentioning that during the coal seam excavation process, cemented carbide picks often collapse due to impact loads. This is mainly due to the uncertainty of coal seam geology, which prevents the tooth head from being in complete contact with the coal seam, and the coal seam also contains impurities such as gangue, which is also one of the reasons for poor contact between the tooth head and the coal seam. Under the action of alternating loads, the pick is prone to cracks due to impact fatigue and thermal fatigue, and is therefore damaged.
In order to improve the failure problem of cemented carbide picks, we can improve its performance by adjusting the particle size, composition and proportion of the alloy. Specifically, the cobalt content in the alloy can be appropriately increased (8%~13%). Cobalt can effectively improve the thermal fatigue resistance, plasticity and relaxation stress of the alloy; the appropriate tungsten carbide (WC) powder particle size and Ratio: Generally speaking, the smaller the particle size of WC powder, the larger the surface area, which will increase the mean free path of cobalt, which is equivalent to increasing the cobalt content, which is beneficial to improving the toughness of the alloy. In addition, in order to enhance the effect of the cobalt phase, the picks can be appropriately heat treated.
