| 摘要 |
PURPOSE:To enable the accurate estimation of the quality of a steel material after hot rolling under any conditions when a plate, a hot strip or the like is manufactured by hot rolling, by attaining the desired strength according to a strength estimating attaining the desired strength according to a strength estimating equation including terms determined by structures and grain size. CONSTITUTION:In order to attain the desired strength, hot rolling is carried out by setting the grain size of ferrite and the strength and volume fraction of each of ferrite, pearlite, bainite and martensite structures so as to satisfy the strength estimating equation (where TS is tensile strength, sigma deg. is a parameter expressing the strength of each structure, V is volume fraction, F is ferrite, P is pearlite, B is bainite, M is martensite, and each of A1-A6 is a constant). By this method, factors related directly to strength and handled, and the relation among them is prescribed, so the strength of a steel material can be accurately estimated independently of changes in conditions during rolling and cooling or the structure of the steel material. |
