| 摘要 |
PURPOSE:To obtain a sintered tool steel having dense structure and excellent in mechanical properties, by alternately carrying out a stage in which a green compact of ferrous-alloy powder is sintered at a temp. higher than its solidus temp. and a stage in which the above green compact is subjected to temp. fall down to a temp. lower than the solidus temp. to undergo degassing. CONSTITUTION:The green compact composed of the powder of ferrous alloy such as high-speed steel, tool steel for die, etc., is heated and the sintered in the presence of liquid phase. At that time, the stage where the green compact is subjected to temp. raise up to the temp. higher than the solidus temp. of the ferrous alloy to under go sintering and the stage where the green compact is subjected to temp. fall down to the temp. lower than the solidus temp. to remove gas existing in the green compact alternately carried out. Moreover, in the final sintering stage, the temp. is raised up to a temp. higher than those in the former sintering stages of the green compact.
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