High hardness, high heat hardness and good wear resista […]
High hardness, high heat hardness and good wear resistance, which are the main performance characteristics of cemented carbide. Because the cemented carbide is made of high hardness, high wear resistance and high heat stable carbide as the skeleton, it plays a hard and wear-resistant role. Therefore, when used as a cutting tool, its wear resistance, life and cutting speed are significantly improved compared with high-speed steel. High compressive strength, higher than high speed steel, but low bending strength. Its modulus of elasticity is high, but its toughness is very poor.
In addition, cemented carbide also has good corrosion resistance and oxidation resistance, and its thermal expansion coefficient is lower than that of steel Low bending strength, high brittleness, and poor thermal conductivity are the main disadvantages of cemented carbides. Therefore, shock and temperature changes should be avoided during processing and use.
Due to its high hardness, cemented carbide cannot be processed by general cutting methods, only by electrical machining electric spark, wire cutting and special grinding wheel grinding. Generally, a hard alloy product of a certain shape and specification is fixed to a steel cutter body or a mold body by bonding, brazing or mechanical clamping.
The chemical composition of tungsten-cobalt-based cemented carbides is mainly WC and Co. Its grades are expressed in terms of the percentages of the first letters and plus cobalt of "hard" and "cobalt". For example, YG8 represents a tungsten-cobalt-based cemented carbide containing 8% of cobalt the balance being WC. If the carbide particles in the alloy are coarser, add after the grade, such as if the carbide particles are finer, add "X" after the grade, such as YG6X. The same alloy, the finer the particles, the higher the hardness and wear resistance, and the strength is slightly reduced. On the contrary, the hardness and wear resistance are lowered, and the strength is slightly increased.
The content of cobalt in the alloy has a great influence on its properties. Generally, the higher the cobalt content, the higher the strength and toughness, and the lower the hardness and wear resistance. Therefore, tungsten-cobalt-based hard alloys with a high cobalt content are commonly used in the manufacture of rough-working cutting tools and die-cutting, punching, drawing, and cold-pressing molds. Generally, tungsten-cobalt-based hard alloys are commonly used to manufacture cutting tools for processing brittle materials such as cast iron and non-ferrous metals, and various molds and gauges.
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