MANUFACTURING METHOD OF SHEET OF AUSTENITIC IRON-CARBON-MANGANESE STEEL WITH HIGH RESISTANCE AGAINST TO DECELERATED CRACK FORMATION AND SHEET RECEIVED BY THIS METHOD Russian patent published in 2009 - IPC C21D8/04 C21D6/00 C22C38/04 

FIELD: metallurgy.

SUBSTANCE: it is made steel, containing, wt %: 0.45 ≤ C ≤ 0.75; 15 ≤ Mn ≤ 26; Si ≤ 3; Al ≤ 0.050; S ≤ 0.030; P ≤ 0.080; N ≤ 0.1, at least, one element selected from the group: 0.050 ≤ V ≤ 0.50; 0.040 ≤ Ti ≤ 0.50; 0.070 ≤ Nb ≤ 0.50; 0.070 ≤ Cr ≤ 2; 0.14 ≤ Mo ≤ 2 and, not necessarily, one or more of elements selected from group: 0.0005 ≤ B ≤ 0.003; Ni ≤ 1; Cu ≤ 5, the rest are iron and unavoidable admixtures, formed during melting, from this steel it is cast semi-product, it is heated up to temperature between 1100 and 1300°C, it is implemented hot rolling at finishing temperature 890°C or higher, winding into coil at temperature lower 580°C, cold rolling, annealing, which includes heating stage at a heating rate V_h (°C/c) up to the temperature T_s (°C), isolation at temperature T_s during time t_s (c), cooling at a rate V_c (°C/c) with optional following isolation at temperature T_u(°C ) during time t_u(c), herewith parametres V_h, T_s, t_s, V_c, T_u, t_u are regulated with providing of receiving of at least one element in the form of precipitated carbides, nitrides or carbonitrides in amount, wt %: 0.030 ≤ V_p ≤ 0.150; 0.030 ≤ Ti_p ≤ 0.130; 0.040 ≤ Nb_p ≤ 0.220; 0.070 ≤ Cr_p ≤ 0.6; 0.14 ≤ Mo_p ≤ 0.44.

EFFECT: receiving of high-strength sheet and simultaneously high plasticity at very high resistance against decelerated crack formation.

20 cl, 3 tbl, 1 ex