| 摘要 |
The invention relates to a powder metallurgical method for producing high speed steel products, the shape of which is close to the desired final shape of the product, i.e. according to the so called near net shape technique. The method comprises the following steps: (a) a starting powder consisting of high speed steel is soft annealed in a first annealing step in a non-oxidizing environment, (b) the soft annealed powder is fragmented mechanically, (c) the fragmented powder is annealed in the austenitic region of the steel in a second annealing step in a non-oxidizing environment thereby to improve the compactability of the fragmented powder by reducing its hardness and by forming aggregates of fragmented particles, compactability signifying the ability of the powder to form a manageable powder body, a so called green body, (d) the powder is compacted mechanically, after being annealed and having formed aggregates in said second annealing step, in a die to form a green body of the desired product shape, (e) the green body is sintered in a non-oxidizing environment until communicating porosity has been eliminated, and (f) the sintered body is subjected to hot isostatic compaction to full density. |
