Surface Modification of Cast Iron by Friction Stir Process

• Published in: Chūzō kōgaku Vol. 80; no. 1; pp. 15 - 21
• Main Authors: Yamaguchi, Yasufumi, Fujii, Hidetoshi, Kiguchi, Shoji, Nogi, Kiyoshi
• Format: Journal Article
• Language: Japanese
• Published: Japan Foundry Engineering Society 25.01.2008
• Subjects: cast iron; friction stir processing; hardness; martensite; surface modification
• ISSN: 1342-0429; 2185-5374
• DOI: 10.11279/jfes.80.15

A new surface hardening technology for cast irons was developed by applying the friction stir process (FSP) in which the matrix can be controlled in the solid state using frictional heat. Flake graphite cast iron(FC300) and spheroidal graphite cast iron(FCD700) were used to investigate the validity of this new method. As a result, it has become clear that a Vickers hardness of about 700HV is obtained for both the flake graphite cast iron and spheroidal graphite cast iron, and that the hardness depends on the size and the density of the martensite phase. Moreover, the hardness can be controlled down to about 500HV by changing the stirring degree. For previous hardening methods, post surface-processing was required because a large distortion is generated. However, for this new method, a lot of advantages such as a higher surface hardness and no required post surface-processing are obtained.