Patent ID: 8951366
Filing Date: 2015-02-10
Classification: C21D,C22C,C23C

Abstract:
1. A high-strength cold-rolled steel sheet comprising: by mass%, C: 0.10% to 0.40%; Mn: 0.5% to 4.0%; Si: 0.005% to 2.5%; Al: 0.005% to 2.5%; Cr: 0% to 1.0%; and a balance of iron and inevitable impurities, wherein an amount of P is limited to 0.05% or less, an amount of S is limited to 0.02% or less, an amount of N is limited to 0.006% or less, a microstructure thereof includes 2% to 30% of retained austenite by area percentage, martensite is limited to 20% or less by area percentage in the microstructure, an average particle size of cementite in the microstructure is 0.01 μm to 1 μm, and 30% to 100% of the cementite has an aspect ratio of 1 to 3.