Patent ID: 8926766
Filing Date: 2015-01-06
Classification: C21D,C22C

Abstract:
1. A low yield ratio, high strength and high uniform elongation steel plate containing 0.06% to 0.12% C, 0.01% to 1.0% Si, 1.2% to 3.0% Mn, 0.015% or less P, 0.005% or less S, 0.08% or less Al, 0.005% to 0.07% Nb, 0.005% to 0.025% Ti, 0.010% or less N, and 0.005% or less O on a mass basis, the remainder being Fe and unavoidable impurities; the low yield ratio, high strength and high uniform elongation steel plate having a metallographic microstructure that is a two-phase microstructure consisting of bainite and M-A constituent, the area fraction of the M-A constituent being 3% to 20%, the equivalent circle diameter of the M-A constituent being 3.0 μm or less; the low yield ratio, high strength and high uniform elongation steel plate having a uniform elongation of 7% or more and a yield ratio of 85% or less; the low yield ratio, high strength and high uniform elongation steel plate having a uniform elongation of 7% or more and a yield ratio of 85% or less after being subjected to strain ageing treatment at a temperature of 250° C. or lower for 30 minutes or less; wherein the steel plate has a base material toughness of 200 J or more at −20° C., and a tensile strength that is no greater than 677 MPa.