Effect of Alloying Element Ni Small Quantity Addition on the Mechanical Properties and Surface Roughness of Flake Graphite Cast Iron

• Main Authors: Zi-Xian Zhan, 詹子賢
• Other Authors: 楊榮顯
• Format: Others
• Language: zh-TW
• Published: 2013
• Online Access: http://ndltd.ncl.edu.tw/handle/83105269606728315845

碩士 === 逢甲大學 === 機械與電腦輔助工程學系 === 101 === The purpose of this study is to investigate the effect of adding alloying element Ni(0.0 to 3.0 wt.%) on the mechanical properties(tensile strength, percentage of elongation, impact value) and surface roughness of flake graphite cast iron castings with 80, 40, 20 mm thickness. The result of experiment show that in the mechanical properties, the tensile strength increased by increasing the addition amount of alloying element Ni, but the percentage of elongation and impact value decreased comparatively. Overall, the amount of alloying element Ni is added from 0.0 to 3.0 wt.%, the tensile strength increases from 206.1 MPa to 215.1 MPa, the percentage of elongation decreases from 2.73% to 2.39%, and the impact value decreases from 1.423 J/cm2 to 1.046 J/cm2. Under fixed machining condition, the surface roughness of the machined casting for the whole casting and different thickness portions are improved distinctly, by increasing the amount of alloying element Ni. For the whole casting, the average surface roughness standard deviation decreases from 0.091 to 0.041, for the adding amount of Ni increased from 0.0 wt.% to 3.0 wt.%. For the casting in different thickness 20 mm, 40 mm, 80 mm, the average surface roughness standard deviation decrease from 0.079, 0.099, 0.106, to 0.033, 0.036, 0.033. In the other word, for thicker casting, the effect of adding alloying element Ni on the improvement of the surface roughness for the machined casting is more obviously. Compare the experimental result of the various mechanical properties and surface roughness from this study, to the metallographic microstructure analysis result of area percentage of matrix(pearlite, ferrite, graphite) that changed with the addition of alloying element Ni, reasonable explanation and reciprocal proof could be obtained. In addition, by adopting the obtained results of the mechanical properties and surface roughness, this research also successfully obtained several accurate regression equations(r2 > 0.9) between the alloying element Ni addition amount and the tensile strength, impact value, average surface roughness standard deviation.