Physical metallurgy of modern high strength steel sheets

Lightening of automobile bodies is required from the viewpoint of saving energy which contributes to ameliorating an ecological problem. A useful means of doing this is the application of high strength steel sheets to automobile bodies. The inferior formability of high strength steel sheets in comparison with that of mild steel sheets, however, hinders their broad application. But in recent years, many high strength steel sheets with good formability have been developed using sophisticated physical metallurgy. In this paper, the recent development of modern high strength steel sheets is reviewed paying special attention to their physical metallurgy which realized the improvement of their formability.