Patent ID: 7727343
Filing Date: 2010-06-01
Classification: B21B,C21D

Abstract:
1. A warm control rolling method, for manufacturing steel mainly composed of fine ferrite particle texture with average ferrite grain size controlled by a desired value of 3 μm or less, which comprises, rolling the steel, in continuous multipass rolling at a rolling temperature range of 350° C. to 800° C., in a condition where the rolling condition parameter expressed in formula (1) ε: strain t: duration from start till end of rolling (s) T: rolling temperature (° C., or average of rolling temperature of each pass in the case of multipass rolling) Q: 254,000 if mother phase of texture just before rolling is ferrite, bainite, martensite, or pearlite; 300,000 if mother phase is austenite, is 11 or more (in the case the texture just before rolling is ferrite, bainite, martensite, or pearlite, that is, Fe crystal structure is bcc) or 20 or more (in the case the texture just before rolling is austenite, that is, Fe crystal structure is fcc), and wherein at least one pass interval is longer than 20 seconds, so that the material temperature upon start of rolling of each rolling pass does not exceed the maximum temperature of 800° C., and the material temperature during rolling and right after final rolling (within 1 second) is not 350° C. or lower, and so that, in each rolling pass, temperature T