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.

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As applications of the mathematical models, the on-line prediction of the microstructure and strength. the resistance to hot deformation and the cooling curves affected by the heat evolution dueto transformation are given.Finally, the future work and prospective of the mathematical model in hot strip rolling is also presented.

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Considerable progress in developing flat-rolled steel grades has been made by the Chinese steel industry over the recent two decades. The increasing demand for high-performance products to be used in infrastructural projects as well as in production of consumer and capital goods has been driving this development until today. The installation of state-of-the-art steel making and rolling facilities has provided the possibility of processing the most advanced steel grades. The production of high-performance steel grades relies on specific alloying elements of which molybdenum is one of the most powerful. China is nearly self-sufficient in molybdenum supplies. This paper highlights the potential and advantages of molybdenum alloying over the entire range of flat-rolled steel products. Specific aspects of steel property improvement with respect to particular applications are indicated.

It is well known that nickel is a beneficial alloying element in copper bearing steels as it prevents hot shortness. On the other hand, the addition of tin promotes hot shortness. T hough some mechanisms for promoting these phenomena have been suggested, a quantitative discussion has still failed to establish the cause. In the present study, changes in the composition in the vicinity of the scale/metal interface owing to high temperature oxidation were experimentally determined using pure irons with copper, nickel, and tin additions. T he experimental findings, such as the fraction of liquid phase and the change in composition in the progress of scale formation, were then explained by thermodynamic considerations using the Fe-Cu-Ni and Fe-Cu-Sn phase diagrams calculated from a computerised thermodynamic database. T he thermodynamic considerations were also applied to a quantitative discussion on hot shortness and some measures for preventing hot shortness of copper bearing steels were suggested.MST /4285