Study on the High Temperature Tensile Property and Oxidation Resistance of Fe-C-Si-Mo Ductile Cast Iron

• Main Authors: Wei-Ber Chen, 陳偉博
• Other Authors: Rong-Shean Yang
• Format: Others
• Language: zh-TW
• Published: 2008
• Online Access: http://ndltd.ncl.edu.tw/handle/41053327687124522408

碩士 === 逢甲大學 === 機械工程學所 === 96 === The object of this study is to investigate the high temperature tensile property and oxidation resistant property of Fe-C-Si-Mo ductile cast iron. The content of carbon is fixed at 3.8wt% in all specimens, but the content of Si (3.8%, 4.0%, and 4.2%) and Mo (0.6%, 0.7%, and 0.8%) are varied. The high temperature tensile property and oxidation resistant property under variable temperatures (973K, 1073K, and 1173K) are studied. Moreover, the microstructure evolution is observed by SEM and optical microscope; the oxidation layers are observed by EDS and XRD. From this research, high temperature tensile strength increases with increasing the content of molybdenum. The specimens with 4.0wt% Si and 0.8wt% Mo have the best high temperature tensile strengths which are 230MPa, 88.6MPa, and 37.63MPa at 973K, 1073K, and 1173K, respectively. The high temperature yield strength also increases with increasing the content of molybdenum, and its value is 60~70% of tensile strength approximately. Referring to the slope of tensile curve below the proportional limit, the larger slope means smaller elongation. The experimental results indicate that the slope of specimens with Mo is higher than the specimens without Mo at room temperature or high temperature. The oxidation resistant property is better with increasing the content of silicon. The specimen with 4.2wt% Si have the best oxidation resistant property, and the oxidation layers are the thinnest at all testing temperatures. The specimen with 4.0wt% Si and 0.8wt% Mo have the best oxidation resistant property at 1073K, and their weight increment rate is less than 0.1%. The oxidation layers become thinner with increasing the content of Mo. The chemical composition of outer oxidation layer is mainly Fe2O3 and inner oxidation layer are SiO2 and Fe3O4 (or FeO). The experimental results show that the high temperature tensile property and oxidation resistant property of Fe-C-Si-Mo ductile cast iron can be enhanced effectively by adding alloying element Mo. It would be beneficial for the practical high temperature application in the industry.