| Summary: | 碩士 === 國立臺北科技大學 === 材料科學與工程研究所 === 99 === The research discusses the effect on microstructure and mechanical properties of a high silicon ductile iron by adding Chrome and Molybdenum. In the experiment, melting method is used to adjust the chemical composition in a ductile iron. This experiment was conducted under the following fixed conditions, Carbon content of 3.2 wt% and Silicon content of 4.4 wt%. Also, additive volumes are added as follow, Chrome content of 0.63 wt%, 0.99 wt and 1.32 wt%, Molybdenum content of 1.1wt%, 1.6 wt% and 2.0 wt%. In addition, Metallographic Structure, Hardness, Room Temperature Tensile Testing, 650℃ Tensile Testing, Room Temperature Impact and 650℃High Temperature Impact were also considered to analyze the effect. Lastly, it also addresses the strengthening effect of the high silicon ductile iron when the best parameters of Cr and Mo Compound are added in the test.
Based on the result of the experiment, the tensile strength was enhanced in the room temperature tensile testing and 650℃Tensile Testing when Cr and Mo are added. However, if compound is added separately, adding Cr will get a better result regarding the tensile strength. In room temperature, (Best Result), 657 MPa by 0.99 wt% of Cr., 603.7 MPa by 1.1 wt% of Mo., 685 MPa by 1.3 wt.% of Cr. together with 1.9 wt.% of Mo; in 650℃Tensile Testing,(Best Result), 265.9 MPa by 1.32 wt.% of Cr., 214.7 MPa by 2.03 wt% of Mo., 360.9 MPa by 1.3wt.% of Cr. together with 1.9wt.% of Mo. Nevertheless, although Cr and Mo can stabilize Pearlite, reduce the chance of ghraphitization in high temperature testing and also enhance the tensile strength, the Impact Property will lose consequently and appears to be an inverse ratio with the increase of additive volume.
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