PROCEDURE FOR PRODUCTION OF SHEET OUT OF IRON-CARBON-MANGANESE AUSTENITE STEEL SUPER-RESISTANT TO DELAYED CRACKING AND SHEET MANUFACTURED BY THIS PROCEDURE Russian patent published in 2011 - IPC C21D8/04 C21D6/00 C22C38/04 C23C30/00 

FIELD: metallurgy.

SUBSTANCE: there is melted steel containing wt %: 0.35 ≤ C ≤ 1.05, 15 ≤ Mn ≤ 26, Si ≤ 3, Al ≤ 0.050, S ≤ 0.030, P ≤ 0.080, N ≤ 0.1, at least one metal element X chosen from vanadium, titanium, niobium, molybdenum and chromium at amount: 0.050 ≤ V ≤ 0.50, 0.040 ≤ Ti ≤ 0.50, 0.070 ≤ Nb ≤ 0.50, 0.14 ≤ Mo ≤ 2, 0.070 ≤ Cr ≤ 2, and, not necessary, one or several elements chosen from 0.0005 ≤ B ≤ 0.010, Ni ≤ 2, Cu ≤ 5, iron and unavoidable impurities the rest. Semi-finished product cast out of this steel is further heated to temperature 1100 -1300° C and hot rolled to temperature of finish rolling of 890°C or above. There is produced sheet successively wound into a coil at temperature below 580°C. The coil is at least once cold rolled and subjected to at least one operation of annealing at velocity of heating V_h from 2 to 10°C/sec at temperature T_s from 700 to 870°C from 30 to 180 sec and at rate of cooling from 10 to 50°C/sec. Coating out of Zn or alloy Zn-Y is applied on the sheet, where Y corresponds to one or more from Ni, Cr, Mg. The sheet is subjected to at least one conditioning in atmosphere of pure nitrogen or argon with a dew point below -30°C at temperature 0 within ranges from 250 to 900°C during time t. Also, temperature and time meet the ratio: θ(°C) Ln(t(sec)) ≥ 2200.

EFFECT: manufactured steel sheets possess high durability and plasticity which reduces weight and increases safety owing to absorption of power at impact.

39 cl, 4 dwg, 4 tbl, 1 ex