Patent ID: 6190469
Filing Date: 2001-02-20
Classification: C21D,C22C

Abstract:
A method for manufacturing a hot rolled transformation induced plasticity steel containing Cu, C, Si, Mn and Al and by carrying out a hot rolling, a cooling and a coiling, comprising the steps of:preparing a steel consisting essentially of in weight % 0.15-0.3% C, 1.5-2.5% Si, 0.6-1.8% Mn, 0.02-0.10% Al, 0.6-2.0% Cu, 0.6-2.0% Ni, 0-0.01% Ca, balance Fe and inevitable impurities;finish hot rolling the steel at a temperature of 750-880.degree. C.;initiating a water cooling at a temperature of 680-740.degree. C.;terminating the water cooling at a temperature of 240.times.(% Mn+% Ni)-140(.degree. C.).ltoreq.water cooling terminating temperature .ltoreq.540.degree. C.; and thencoiling,wherein the hot rolled transformation induced plasticity steel has a multi-phase structure consisting of ferrites bainites and retained austenites, and fine .epsilon.--Cu precipitates having sizes of 5-20 nm are present in the ferrites.