Patent ID: 9427939
Filing Date: 2016-08-30
CPC Classification: B32B,C21D,C22C,Y10T

Claim Text:
1. A cold rolled and annealed steel sheet, the composition of which, expressed in per cent by weight, comprises: the remainder of the composition consisting of iron and the inevitable impurities resulting from processing, a microstructure of the composition including, in area proportions, 5 to 20% polygonal ferrite, 10 to 15% residual austenite, 5 to 15% martensite, the balance being bainite in the form of laths and including, between these laths, inter-lath carbides such that a number N of the inter-lath carbides larger than 0.1 micrometer per unit of surface area is less than or equal to 50000/mm the steel sheet having a mechanical strength greater than or equal to 1000 MPa and a uniform elongation greater than or equal to 12%.