延性鑄鐵表面氧化膜處理及機制之研究

Treatment and Mechanism of Ductile Cast Iron Surface Oxidation Layer

楊榮顯(Rong-Shean Yang) ； 張柏志(Po-Chi Chang) ； 洪俊傑(Jun-Jie Hong)

《鑄造工程學刊》 43卷4期 (2017/12) Pp. 1-16

摘要

本研究主要目的是在探討延性鑄鐵表面氧化膜之處理與機制。延性鑄鐵表面氧化膜主要是針對表面色澤、金相顯微組織與熱處理條件之相互關係。延性鑄鐵表面色澤在下述3個熱處理溫度時之差異較大，分別為573 K、873K、1173 K。熱處理溫度573 K之延性鑄鐵試片表面色澤呈現藍黑色、873 K呈現些微紅褐、1173 K則呈現較深之藍色。熱處理溫度873 K之試片經分析後，三氧化二鐵(Fe_2O_3)及四氧化三鐵(Fe_3O_4)兩種鐵之氧化物同時存在於表面。1173 K之試片經分析後，最外層之表面僅存在三氧化二鐵(Fe_2O_3)之鐵氧化物，其氧化膜已生成相當之厚度。熱處理溫度於873 K時，延性鑄鐵試片金相顯微組織中的肥粒鐵面積率增加、波來鐵面積率減少；於1173 K時，則肥粒鐵面積率減少、波來鐵面積率增加。熱處理溫度升高時，對於球墨數及球墨粒徑而言，其趨勢均為下降，但對於球化率則無影響。

關鍵字

延性鑄鐵 ； 表面氧化膜 ； 熱處理 ； 金相顯微組織

並列摘要

The purpose of this study is to investigate the treatment and mechanism of ductile cast iron surface oxidation layer. The relations between surface color, metallographic microstructure and heat treatment conditions of ductile cast iron surface oxidation layer also are discussed. There are mainly three different results at the heat treatment temperature, that the ductile iron casting surface color is relatively difference, there are 573 K, 873 K, 1173 K. Ductile iron specimens surface color is blue-black after the heat treatment temperature of 573 K, the reddish brown color after the 873 K and the deeper blue after the 1173 K. After analyzing, the Hematite (Fe_2O_3) and Magnetite (Fe_3O_4) iron oxide simultaneously appear on the surface of specimen with the heat treatment temperature of 873 K. The Hematite (Fe_2O_3) iron oxide only appears on the surface of specimen with the heat treatment temperature of 1173 K. The ductile cast iron specimens have generated considerable oxide thickness after the heat treatment temperature of 1173 K. When heat treatment temperature of 873 K, the metallographic structure of ductile cast iron specimens increase in ferritic area ratio and decrease in pearlite area ratio. When heat treatment temperature of 1173 K, the metallographic structure of ductile cast iron specimens increase in pearlite area ratio and decrease in ferritic area ratio. For the graphite nodule counts and the nodular graphite diameters of ductile cast iron, the trends are falling down when increasing the heat treatment temperature. The nodularity of ductile cast iron specimens are not affected by the heat treatment temperature.

並列關鍵字

Ductile cast iron ； Surface oxidation layer ； Heat treatment ； Metallographic microstructure