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정하돈 한국마린엔지니어링학회 1999 한국마린엔지니어링학회지 Vol.23 No.5
For the purpose of increasing compressed air pressure higher than 30bar lightening weight and decreasing installation area of air compressor used for shipboard and industrial power plant it is necessary to arrange its cylinders as a w-type or v-type construction multi-stage compression pro-cess more than two stages and to increase its operation speed higher than 1200rpm In this recip-rocating type air compressor operated in high speed having a crank mechanism and complicate cylinder arrangement there is a vibration problems which can be solved by balancing its recipro-cating parts with balance weight and approriate arranging of cylinder's arrangement angles.
구상흑연 주철의 열처리 조건이 기계적 성질에 미치는 영향
전언찬,정하돈,김순경,김용직 東亞大學校 大學院 1998 大學院論文集 Vol.23 No.-
Because the spheroidal graphite cast iron, the cast iron cristallized the graphite to sphericity during the solidification process after annexing Mg etc to the general grey cast iron furnace, the form of the graphite is more spheric than the grey cast iron, has the less notch effect, it is a very excellent metal material on the strength an toughness due to the decrease of the stress concentraion. Therefore, the case which uses it instead of forfing or case steel material used for the industrial machinery parts of various kinds and automobile parts is increasing gradually. The purpose of this study is to increase abration resistance after improving the hardness of the sphericity graphite cast iron used as the valve seat of air compressor. We obtained the following result through experiment on the change of structure and mechanical property according to the heat treat cycle. Because the abration resistance is closely related with the volume of martensite, the hardness and the aration resistence have improved and the structure of martensite has increased as the cooling rate is fast. Therefore, the best heat treatment which considers tensile strength and elongation percentage, the most suitable method, is that austempering is done the constant temperature process about 2 hours at 750℃ then the cooling is done in the condition of opened furnare after making the condition of austenitizing do the constant temperature process ofr 2 hours at 950℃.