| Summary: | 碩士 === 逢甲大學 === 機械與電腦輔助工程學系 === 104 === The purpose of this study is to investigate the design of ductile cast iron pot spout and the treatment and mechanism of surface oxidation layer. The design of pot spout includes height of spout, spout inlet and outlet area ratio. The relations between surface color, metallographic microstructure and heat treatment conditions of ductile cast iron surface oxidation layer also are discussed.
The result of experiment show that the spout height of ductile cast iron pot should be designed to zero that is parallel to the top of the total height of pot body. More suitable design for the spout inlet area and the spout outlet area ratio, there are two ways. The first is that when spout inlet area is 10% of the central cross section area of the spot body, and spout outlet area is 10% of spout inlet area. The second is that when spout inlet area is 20% of the central cross section area of the pot body, and spout outlet area is 5% of spout inlet area.
There are mainly three different results at the heat treatment temperature, that the ductile iron casting surface color is relatively difference, there are 573 K, 873 K, 1173 K. Ductile iron specimens surface color is blue-black after the heat treatment temperature of 573 K, the reddish brown color after the 873 K and the deeper blue after the 1173 K. After analyzing, the Hematite (Fe2O3) and Magnetite (Fe3O4) iron oxide simultaneously appear on the surface of specimen with the heat treatment temperature of 873 K. The Hematite (Fe2O3) iron oxide only appears on the surface of specimen with the heat treatment temperature of 1173 K. The ductile cast iron specimens have generated considerable oxide thickness after the heat treatment temperature of 1173 K.
When heat treatment temperature of 873 K, the metallographic structure of ductile cast iron specimens increase in ferritic area ratio and decrease in pearlite area ratio. When heat treatment temperature of 1173 K, the metallographic structure of ductile cast iron specimens increase in pearlite area ratio and decrease in ferritic area ratio. For the graphite nodule counts and the nodular graphite diameters of ductile cast iron, the trends are falling down when increasing the heat treatment temperature. The nodularity of ductile cast iron specimens are not affected by the heat treatment temperature.
The heat treatment temperature of 1173 K is the more appropriate for the ductile cast iron oxidation layer forming after comprehensive survey.
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