the invention relates to a hot rolled sheet which is made from austenitic iron / carbon / manganese steel and which has a resistance of greater than 900 mpa , whereby : resistance x elongation at rupture is greater than 45000 . the chemical composition of the inventive sheet comprises the following concentrations expressed as weight : 0 . 5 %= c = 0 . 7 %, 17 %= mn = 24 %, si = 3 %, al = 0 . 05 %, s = 0 . 03 %, p = 0 . 08 %, n = 0 . 1 % and , optionally , one or more elements such as cr = 1 %, mo = 0 . 4 %, ni = 1 %, ti = 0 . 5 %, nb = 0 . 5 %, v = 0 . 5 %, cu = 5 %, cu = 5 %, the rest of the composition comprising iron and impurities resulting from production . according to the invention , the recrystallised fraction of the steel is greater than 75 % and the surface fraction of precipitated carbides of the steel is less than 1 . 5 %, the average grain size of the steel being less than 18 micrometers .