Cold-rolled and heat-treated steel plates, and the method of manufacturing these steel plates

Abstract

The invention relates to an impregnation of cold-rolled and heat-treated steel of the following composition: 0.1% < Carbon < 0.5%, 1% < Manganese < 3.4%, 0.5% < Silicon < 2.5%, 0.01% < Aluminum < 1.5%, 0.05% < Chromium < 1%, 0.00% < Niobium < 0.1%, 0% < Sulfur < 0.003%, 0.002% < Phosphorus < 0.02%, 0% < Nitrogen < 0.01%, 0% < Molybdenum < 0.5%, 0.001% < Rhitane < 0.01%, 0.01% < Copper < 2%, 0.01% < Nickel < 3%, 0.0001% < Calcium < 0.005%, 0% < Vanadium < 0.1 %, 0 % < Boron < 0.003 %, 0 % < Cerium< 0.1 %: 0 % < Magic < 0.010%, 0% < Zirconium < 0.010% The remaining components are iron and unavoidable impurities, and the structure of this rolled steel sheet includes, by area ratio, 10% to 60% Danille, 5% to 50% Perit, 5% to 25% residual Austenitic, 2% to 20% Martensite, 0% to 25% tempered Martensite, the remainder being tempered Martensite, with a content ranging from 1% to 45%.