| 摘要 |
<p>PROBLEM TO BE SOLVED: To obtain a steel plate of excellent material in high yield by producing a hot rolled steel plate of desired material by accurately predicting changes in a steel structure such as volume ratio of pearlite during hot rolling and cooling and controlling manufacturing conditions from the resultant prediction. SOLUTION: The average austenite grain size d0 before rolling, at the time of extraction from a heating furnace, is determined from the initial grain size model previously determined on the basis of the chemical composition of a cast slab consisting of carbon steel components and heating conditions. By using this grain size d0 , the average austenite grain size da after the final rolling pass and the residual strainΔεa are determined. From da ,Δεa , chemical composition of steel material, and cooling conditions, ferrite volume ratio Vf , ferrite grain size df . and ferrite transformation finishing temp. Tf are determined, and also the pearlite volume ratio Vp during cooling, shown by equation, is determined. Subsequently, from da ,Δεa , Vf , Vp , chemical composition of steel material, and cooling conditions, bainite volume ratio Vb and martensite volume ratio Vm are determined. Cooling pattern after rolling is determined from Vf , df , Vp , Vb , and Vm , and, based on this cooling pattern, cooling control after rolling is performed.</p> |
