Properties of a Newly Developed Galvannealed Steel Sheet with Modified Surface

Since galvannealed steel sheets (GA) are widely used for automobile body parts, they require excellent features such as press formability, resistant spot weldability and phosphatability. We have focused on improving the press formability of GA since the late 1990s, and have developed a new type of surface modified GA which has a lower friction coefficient than conventional GA. The developed surface modified GA based on mild steel is now used by all automakers in Japan, especially for those parts such as side panels that are difficult to form. This paper describes the features of the surface modified GA.