Cold rolled and heat treated steel sheet and a method of manufacturing thereof

A cold rolled and heat treated steel sheet having a composition comprising the following elements, expressed in percentage by weight:

• 0.1%≤Carbon≤0.5%
• 1%≤Manganese≤3.4%
• 0.5%≤Silicon≤2.5%
• 0.01%≤Aluminum≤1.5%
• 0.05%≤Chromium≤1%
• 0.001%≤Niobium≤0.1%
• 0%≤Sulfur≤0.003%
• 0.002%≤Phosphorus≤0.02%
• 0%≤Nitrogen≤0.01%
• and optionally comprising the following elements:
• 0%≤Molybdenum≤0.5%
• 0.001%≤Titanium≤0.1%
• 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%≤Magnesium≤0.010%
• 0%≤Zirconium≤0.010%
• a remainder of the composition being composed of iron and the unavoidable impurities, and a microstructure of the cold rolled and heat treated steel sheet including by area fraction, 10% to 60% Bainite, 5% to 50% Ferrite, 5% to 25% Residual Austenite, Martensite 2% to 20%, Tempered Martensite 0% to 25%, a balance of the microstructure being Annealed Martensite from 1% to 11%,
• wherein the cold rolled and heat treated steel sheet has a tensile strength greater than 960 MPa, a total elongation of 20% or more and a yield strength from 479 MPa to 611 MPa.