ArcelorMittal S.A.
COLD ROLLED AND COATED STEEL SHEET AND A METHOD OF MANUFACTURING THEREOF

Abstract:

A cold rolled and heat treated steel sheet having a composition including elements, expressed in percentage by weight 0.11%.ltoreq.Carbon.ltoreq.0.15%, 1.1%.ltoreq.Manganese.ltoreq.1.8%, 0.5%.ltoreq.Silicon.ltoreq.0.9%, 0.002%.ltoreq.Phosphorus.ltoreq.0.02%, 0%.ltoreq.Sulfur.ltoreq.0.003%, 0%.ltoreq.Aluminum.ltoreq.0.05%, 0%.ltoreq.Nitrogen.ltoreq.0.007%, and can contain one or more of optional elements 0.05%.ltoreq.Chromium.ltoreq.1%, 0.001%.ltoreq.Molybdenum.ltoreq.0.5%, 0.001%.ltoreq.Niobium.ltoreq.0.1%, 0.001%.ltoreq.Titanium.ltoreq.0.1%, 0.01%.ltoreq.Copper.ltoreq.2%, 0.01%.ltoreq.Nickel.ltoreq.3%, 0.0001%.ltoreq.Calcium.ltoreq.0.005%, 0%.ltoreq.Vanadium.ltoreq.0.1%, 0%.ltoreq.Boron.ltoreq.0.003%, 0%.ltoreq.Cerium.ltoreq.0.1%, 0%.ltoreq.Magnesium.ltoreq.0.010%, 0%.ltoreq.Zirconium.ltoreq.0.010% the remainder being composed of iron and unavoidable impurities, the microstructure of said steel sheet comprising, 50 to 80% Ferrite, 10 to 30% Bainite, 1 to 10% Residual Austenite, and 1% to 5% Martensite, wherein the cumulated amounts of Bainite and Residual Austenite is more than or equal to 25%.