E20 Co % 3 1800 1200 1700 6 1650 1500 2300 9 1400 2000 2600 6 1600 2000 2600 9 1450 2350 2700 12 1300 2450 2900 15 1200 2700 2850 6 1400 1900 2250 8 1350 2300 2600 10 1200 2650 2850 SINTERED HARD METAL HIP-DENSIFIED The HIP treatment (hot isostatic pressing) is a hot isostatic recompression of WC - Co - hard metals With this procedure, which is widely used in hard metal technology, the material is recompacted under high pressure (1.2-3 kbar) after sintering in a high-temperature furnace below the sintering temperature. This procedure reduces the residual porosity. This reduction in porosity results in an improvement in the strength properties and, as a result, an increase in the service life of the tools used for pressworking. In addition to the compressive strength, the flexural strength in particular is increased, as can be seen from the diagrams and tables listed. For sheet metal working, carbide grades of medium WC grain size, with 9-12 % Co content, are preferred for a wide range of applications. 2 σbB 2,0 1,5 1,0 2,5 kN/mm ne medium coarse Tungsten Carbide Particle Size a) influence of crystallite size of hard metal phase left: sintered only right: sintered and HIP-treated). 2 σbB 2,0 1,5 1,0 2,5 3,5% 6% 15% kN/mm Cobalt Content: b) Influence of the cobalt content, sample condition as in figure a. Flexural strength sbB of a WC-6Co alloy in the sintered and HIP-treated state as a function of various influencing variables. Porosity in sintered condition: ≥A1 left, not shaded:Sintered condition right, shaded:HIP-treated. Change of Sintered Hard Metal by hot isostatic pressing Tungsten carbide – particle size Hardness HV30 Flexural Strength N/mm2 before after before after feinfine no changes medium coarse
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