HOT ROLLED STEEL PLATE FOR WORKING, HAVING SUPERFINE GRAIN, AND ITS PRODUCTION

摘要

PROBLEM TO BE SOLVED: To produce a hot rolled steel plate for working, which can be easily produced by means of a general hot strip mill and is minimal in anisotropy of mechanical properties and in which superfine grains hitherto impossible by the conventional technique are attained. SOLUTION: This steel plate is an extra low carbon steel plate of <=0.01 wt.% C content and has superfine grains of <=7μm average ferrite grain size. Such a steel plate can be produced by carrying out reduction in a dynamic recrystallization region by reduction passes of >=5 stands and also regulating a plate-passing velocity at the outlet side of final stand to <=800 mpm, at the time of refining a stock of <=0.01 wt.% C content for hot rolling and then performing hot rolling immediately or after temporary heating and subsequent heating up to <=1200 deg.C.