本研究主要是探討添加鉻鉬元素對高矽球墨鑄鐵的顯微組織以及機械性質的影響,實驗時利用熔煉調整球墨鑄鐵之成分,碳含量固定為3.2 wt.%,矽含量固定為4.4wt.%,鉻的添加量為0.63 wt.%、0.99 wt.%、1.32 wt.%,鉬的添加量為1.1 wt.%、1.6 wt.%、2.0 wt.%,並進行金相組織、硬度、室溫拉伸與650℃高溫拉伸、室溫衝擊與650℃高溫衝擊實驗,並將添加鉻、鉬元素在650℃高溫抗拉時強度最佳參數,進行複合添加,探討鉻、鉬合金對於高矽球墨鑄鐵的強化效果。 實驗結果顯示,鉻、鉬元素能有效提升高矽球墨鑄鐵室溫與650℃高溫抗拉強度,在個別添加時添加鉻能比鉬得到更佳的效果,在室溫時Cr 0.99 wt.%時抗拉強度最佳,其強度為657 MPa,添加Mo 1.1 wt.% 拉強度最佳,強度為603.7 MPa,650℃高溫測試時,Cr 1.32 wt.%抗拉強度最佳,抗拉強度為265.9 MPa,Mo 2.0 wt.%最佳,抗拉強度為214.7 MPa,在複合添加後(Cr 1.3 wt.%-Mo 1.9 wt.%)室溫與高溫抗拉強度分別可進一步提升至685 MPa與360.9 MPa,且鉻、鉬元素能有效穩定波來鐵組織,在高溫中降低波來鐵石墨化的產生,鉻、鉬元素雖然可有效提升抗拉強度,但衝擊韌性值卻會因此而喪失,且與鉻鉬元素添加量的增加而下降。
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.