double steel sheet annealing of high resistance and mechanical properties of ductilite, manufacturing process and use of such plates

摘要

the invention relates to a steel plate with double annealing composed, the contents being expressed as a percentage by weight, 0.20% = c = 0.4%, 0.8% = mn = 1.4, 1.6% = so = 3.00%, 0.015 = nb = 0.150%, al = 0.1%, cr = 1.0%, s = 0.006%, p = 0.030%, ti = 0.05%, v = 0.05%, b = 0.003%, n = 0,01%, the rest of the composition being iron and unavoidable impurities as a result of the development, the microstructure is, the proportion of the area.10 to 30% of residual austenite, martensite, 30 to 60% of annealed, 5% to 30% from 10% to 30% bainite, martensite, fresh and less than 10%).it also relates to the manufacturing process as well as the use of such a sheet.