| 摘要 |
PURPOSE:To manufacture a screw for high-temp. compaction excellent in high- temp. softening resistance, strength at high temp., corrosion resistance, and wear resistance, by preparing a bar-shaped stock composed of a powder of high-carbon and high-alloy iron with a specific composition by a powder melallurgical method, forming the above into a screw shape by means of hot working and machining, and then subjecting the above screw to quench-and- temper treatment. CONSTITUTION:At the time of manufacturing a screw of an injection molding machine or an extrusion forming machine for high temp. service by means of powder metallurgy, a powdered Fe-base alloy which has a composition containing, by weight, 1.66-3.5% C, <2.0% Si, <2.0% Mn, 8.0-17.0% Cr, 0.3-8.0% (Mo+0.5W), and 1.5-14.0% (V+Nb) or further containing one or more kinds among 0.2-5.0% Ni, 1.0-8.0% Co, and 0.2-5.0% Cu is compacted by means of hot isostatic pressing. Subsequently, the resulting green compact is hot-worked into bar shape and machined so as to be formed into a screw shape, and then, quench-and-temper treatment is applied to the above to regulated the area ratio of hard metal carbide to 20-35%. |
