Patent ID: 9194032
Filing Date: 2015-11-24
Classification: C21D,C22C

Abstract:
1. A steel sheet comprising, in mass percent: C: 0.02-0.3% Si: 1.0-3.0%; Mn: 1.8-3.0%; P: 0.1% or less (including 0%); S: 0.01% or less (including 0%); Al: 0.001-0.1%; and N: 0.002-0.03%; wherein a remainder is iron and impurities, a microstructure comprises, in terms of area ratio relative to the entire structure, each of the following phases: bainitic ferrite: 50-85%; retained austenite: 3% or more; martensite+the retained austenite: 10-45%; and ferrite: 5-40%, a C content (C a ratio Mn