COLD AND COLD LAMINATED STEEL SHEET AND PROCESS OF MANUFACTURE OF A COLD LAMINATED STEEL SHEET

摘要

Cold -rolled steel plate and cold -rolled steel plate manufacturing process for a cold -rolled steel plate recounted for in this invention is concerned with the manufacture of steel plates with high mechanical strength, uniform elongation and V -bending above the 90? The cold -rolled steel plate has a mechanical strength equal to 1000 MPa, with uniform elongation above or equal to 12% the composition of which includes, the contents being expressed in weight, 0,15% C 0,25%,1,8% Mn 3,0%,1,2% Si 2%,Al 0,10%,0% Cr 0,50%,0% Cu 1%,0% Ni 1%,S 0005%,P 0020%,NB 0015%,Ti 0020%,V 0015%,Co 1%,N 0008%,B 0001%;In which m +ni +cu 3%,Where the remainder of the composition consists of iron and unavoidable impurities resulting from the production, the microstructure being made up, in surface proportions, of 5 to 20% of polygonal ferrita, of 10 to 15% of residual austenite, of 5 to 15% of martensite, the remainder It consists of bainite in the form of slats and comprising, between slats, carbons such that the number n of cross -slate carbides of greater size than 0,1 micrometer per unit surface is less than or equal to 50000 /mm2.