| Summary: | 碩士 === 逢甲大學 === 機械與電腦輔助工程學系 === 104 === The objective of this research is to use JS-CAST simulation software to improve the shrinkage defects of spheroidal graphite cast iron (FCD450-10), and to investigate the effects on the metallographic microstructure and mechanical property of the spheroidal graphite cast iron (FCD450-10), by using chiller design (different thickness) and riser design (riser size), in order to obtain a sound casting with good quality.
The results show that the JS-CAST simulation software simulation resolve spheroidal graphite cast iron (FCD450-10) casting, when setting chillers at the bottom of the casting, and the ratio of chiller thickness to the casting thickness are set to the following values: 1.0 : 2.0, 1.0 : 1.5, 1.0 : 1.0, 1.0 : 0.8. For example of 1.0 : 2.0 ratio case, internal shrinkage of casting decreased slightly. Moreover, through the results of the actual casting and the JS-CAST simulation results are compared, its similarity show to approximately nity percentage. In the case of using riser design, the ratio of the casting thickness to the riser diameter are set to 1.0 : 2.5, 1.0：2.0 ; then through the results of the actual casting and the JS-CAST simulation results are compared, the casting still has internal shrinkage defect. Finally, the riser and chiller are used simultaneously with casting, that is the top riser adopted and has a diameter of 1.5 times the thickness of casting, and with chiller which has thickness of 0.2 times the casting thicknss, it will improve the shrinkage defects.
Based on the above results, for improving the effectiveness of ductile iron castings shrinkage defects, riser design and chiller used alone can not effectively improve the shrinkage defect, but only the use of the top riser design with chiller simultaneouly, can remove the shrinkage defect effectly.
In addition, using chiller or riser design alone, and using the top riser design with chiller simultaneously, affect the metallographic microstructure (matrix structure, graphite size, graphite count …ect.) and mechanical property (hardness) for different positions of casting singnificantly.
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