Sintered high-speed steel is manufactured by using powdered high-speed steel.
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Manufacturing process
Sintered high-speed steel is manufactured by using powdered high-speed steel. The figure shows a simplified diagram that outlines the manufacturing process. The process shows that nitrogen gas of high purity is sprayed under high pressure into molten high-speed steel, in doing so a fine powder is generated. This powder is then put into a mild steel container and vacuum-sealed. After that the container is subjected to high temp-eratures and high pressures. The end product is sintered high-speed steel. General high-speed steel is called dissolved high-speed steel.
Properties
The images below show the microstructure of sintered and dissolved high-speed steel. The black dots that can be seen represent the carbon particles within the microstructure. As it can be seen the carbon particles in the sintered high-speed steel are fine and uniform in size. The grey area is martensite and is a very hard structure. As the carbon grains in the sintered high-speed steel are fine, they prevents the martensite crystals from developing. Therefore the marteniste crystals in the sintered high-speed steel are smaller than those in the dissolved high-speed steel.
Sintered high-speed steel has the following characteristics.
- Higher toughness due to the finer crystal particle size (when compared to that of dissolved high-speed steel) (left graph).
- Better grinding properties than dissolved high-speed steel (right graph).
- Possible to make a wider range of products (for example products with more alloying elements).
Components & use
The chemical compositions for high-speed steels can be found in ISO / FDIS 4957 (JIS4403). For reference purposes you can refer to the table below.
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