COLD-ROLLED AND ANNEALED STEEL SHEET AND PRODUCTION METHOD Russian patent published in 2023 - IPC C21D8/02 C21D9/46 C22C38/38 

FIELD: metallurgy.

SUBSTANCE: invention is related to cold-rolled and annealed steel sheets used in the automotive industry. The sheet has a composition including, wt.%: 0.060≤C≤0.085, 1.8≤Mn≤2.0, 0.4≤Cr≤0.6, 0.1≤Si≤0.5, 0.010≤Nb≤0.025, 3.42N≤Ti≤0.035, 0≤Mo≤0.030, 0.020≤Al≤0.060, 0.0012≤B≤0.0030, S≤0.005, P≤0.050, 0.002≤N≤0.007, if necessary 0.0005≤Ca≤0.005, the rest is iron and inevitable impurities. The sheet has a microstructure with surface consisting of the following fractions: 34-80% bainite, 10-16% martensite and 10-50% ferrite, while the proportion of the surface of non-recrystallized ferrite relative to the entire structure is less than 30%, and martensite consists of self-tempered martensite and fresh martensite, and the proportion of the surface of self-tempered martensite relative to the entire structure is 4-10%.

EFFECT: sheet has the required level of mechanical properties that are uniform throughout the sheet.

18 cl, 2 dwg, 3 tbl