METHOD OF PRODUCTION OF AUSTENITE IRON-CARBON-MANGANESE STELL SHEETS POSESSING HIGH STRENGTH AND ELONGATION PROPERTIES WITH EXEPTIONAL HOMOGENITY Russian patent published in 2009 - IPC C21D8/04 C21D6/00 C22C38/58 

FIELD: metallurgy.

SUBSTANCE: to facilitate ultimate strength of at least 1200 MPa or even 1400 MPa in combination with elongation ensuring product of P-strength by elongation by rupture exceeding 60000 MPa % or 50000 MPa % and also to facilitate uniform mechanical properties hot or cold rolled sheet is made out of steel, chemical composition of which consists of, % wt: 0.85%≤C≤1.05%; 16%≤Mn≤19%; Si≤2%; Al≤0.050%; S≤0.030%; P≤0.050%; N≤0.1%; and, if necessary, of one or more elements chosen from group: Cr≤1%; Mo≤1.50%; Ni≤l%; Cu≤5%; Ti≤0.50%; Nb≤0.50%; V≤0.50%; iron - the rest, and unavoidable impurities, re-crystallised surface of which constitutes 100%; surface of settled carbides constitutes 0% and average value of grain dimension is less or equal to 10 microns. To produce hot rolled sheet a semi-finished product out of this steel is heated to temperature between 1100 and 1300°C, is rolled at finish temperature 900°C or higher, and is conditioned, further it is reeled at temperature 400°C or below. The hot rolled sheet is subject to at least one cycle of treatment each including cold rolling at one or more succeeding passes and re-crystallising annealing.

EFFECT: upgraded ultimate strength.

18 cl, 1 ex, 3 tbl, 1 dwg