Effect of Microstructure on Hot-dip Aluminizing of Carbon Steel

• Main Authors: Chih-Ning Hsu, 許芷寧
• Other Authors: Chaur-Jeng Wang
• Format: Others
• Language: zh-TW
• Published: 2012
• Online Access: http://ndltd.ncl.edu.tw/handle/r7b4vq

碩士 === 國立臺灣科技大學 === 機械工程系 === 100 === This experiment uses commercialized steel materials such as Mild Steel 1005, Medium Carbon Steel 1040 and High Carbon Steel 1080 as the substrate; then uses the heat treatment methods- normalizing, furnace cooling, quenching and spheroidizing to obtain various kinds of micro-structure. Finally, conducts 700℃ hot-dip aluminum, investigates the growth of aluminum layer and external aluminum layer on the carbon steel microstructure in hot dip aluminum. The experiment results show that the specimen coatings in hot-dip aluminum, outer to inner layer are outer Al topcoat, Fe-Al intermetallic layer (mainly Fe2Al5), and various microstructures subtracts respectively. The carbon in the carbon steel, whether it is in the forms of carbon solid solution, spherical cementite or pearlite, all impede the growth of Fe2Al5, therefore the lower the carbon content in steel, the faster the Fe2Al5 layer grows. In addition, the uniformity of the Fe2Al5 layer is influenced by the distribution of the substrate carbon, the more uniform distribution of carbon, the smaller variance in Fe2Al5 layer thickness. Furthermore, the biggest factor affecting thickness of external aluminum layer is the amount of carbide in aluminum layer. The external aluminum layer thickness increases as the amount of carbide in steel material increases, while the thickness variances are not subject to amount of carbon in the steel materials, all specimen decrease in variance as increase in time of hot dip.