21

2019

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05

What do you know about the types and uses of cemented carbide tools that are more expensive than gold?

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What is the composition of cemented carbide?
Cemented carbide is made of carbide (called hard phase) and metal (called bonding phase) with high hardness and melting point by powder metallurgy process. Among them, WC, TiC, TaC, NbC and other carbides are commonly used in cemented carbide tools. The common binder is Co, and the titanium carbide base binder is Mo, Ni
The physical and mechanical properties of cemented carbide depend on the composition of the alloy, the size of the powder particles and the sintering process of the alloy. The more hard phases with high hardness and high melting point, the higher the hardness and high temperature hardness of the alloy, the more adhesive, and the higher the strength. The addition of TaC and NbC in the alloy is beneficial to refine the grain and improve the heat resistance of the alloy. The commonly used cemented carbide brands contain a large amount of WC and TiC, so the hardness and wear resistance, The heat resistance is higher than that of tool steel, the hardness at room temperature is 89~94HRA, and the heat resistance is 80~1000 degrees.
There are four kinds of commonly used cemented carbide: tungsten cobalt (YG), tungsten titanium cobalt (YT), tungsten titanium tantalum (niobium) cobalt (YT) and titanium carbide (YN).
YG tungsten-cobalt alloy is divided into K-type alloy, which is characterized by higher bending strength and toughness than P-type alloy, can withstand the impact on the tool, and can reduce the edge collapse during cutting, but its heat resistance is worse than P-type alloy, because it is mainly used for processing cast iron, non-cast iron materials and non-metallic materials, and the chip is in the form of fragmentation when processing brittle materials. K-type alloy has good thermal conductivity, which is conducive to reducing the cutting temperature. In addition, K-type alloy has good grinding performance, It can grind sharp edges, so it is also suitable for processing non-cast iron materials and fiber laminated materials.
P-type tungsten, titanium and cobalt have high hardness, especially high heat resistance, good adhesion resistance and oxidation resistance. It is mainly used to process plastic materials represented by steel. When processing steel, plastic deformation is large, friction is severe, cutting temperature is high, its special alloy wear is slow, and tool life is high, but it is not suitable for processing stainless steel and titanium alloy.
When P01 of the P alloy is titanium carbide base, the original metal standard is YN, which uses TiC as the main component and Ni and Mo as the bonding metal, and is suitable for high-speed finish machining of alloy steel, hardened steel, etc.
M type alloy YW is added with rare metal carbides to improve the performance of the alloy. The most significant effect is the addition of TaC or NbC. The general mass fraction is about 4%. When the physical fraction of TaC in the alloy reaches 12%~15%, it can improve the ability to resist the periodic temperature change of the body, prevent cracks, and improve the ability to resist plastic deformation. This type of alloy can adapt to intermittent cutting and milling, and is not easy to crack.
Its main characteristics are grain refinement, improved deformation resistance and high temperature performance, while maintaining high hardness, suitable for rough machining of steel.
 

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