cemented carbide die materials need to have four major properties:
1. Must have high and strong resistance: the mold must simultaneously accept large squeezing force, bending stress, impact and other messy loads during the extrusion process. Therefore, it is requested that the selected materials should have high resistance after heat treatment. Therefore, the mold material should have excellent hardenability, so as to ensure that the mold can be hardened and evenly arranged. Large carbides and severe deflection, fiber directionality and non-metallic inclusions and other internal defects, will reduce the strong resistance of the mold, or cause stress to build up when loaded, and cause early damage to the mold.
2. Must have very good wear resistance: the mold should have high wear resistance to ensure a normal service life and produce large quantities of qualified extrusions. Generally speaking, the hardness of steel is directly proportional to the wear resistance under certain conditions. Therefore, the mold material must not only have sufficient hardenability, but also high hardenability. In addition to the hardness, the decisive factors are the thickness, composition, excess and amount of carbide precipitated by the heat treatment, size, type, dispersion, and hardness of the matrix. For example, high-speed steel and low-alloy tool steel have the same hardness value after heat treatment. In actual use, the wear resistance of the former is much higher, and the wear resistance of cemented carbide with more than 80% WC is higher than that of steel. Dozens of times. Therefore, when mass kneading is produced, in order to obtain the long service life of the mold, the high-speed steel and cemented carbide with high quotation and technical disorder are still used as mold materials.
3. There must be sufficient thermal stability: each time continuous production, the temperature rise of the mold sometimes reaches or exceeds 200 ℃, which will reduce the strength and hardness of the mold material with 160~180 ℃ as the tempering temperature. Therefore, the mold material used for higher temperature rise should have outstanding anti-tempering stability.
4. Must have outstanding technicality: the manufacturing cycle of cold extrusion dies is long, the technology is messy, and the precision is high. Usually all must be through casting, cutting, heat treatment, grinding or other finishing. Therefore, as long as the technicality is compared with outstanding materials, can we meet the demand for production.
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