METHOD FOR MAKING THIN SHEETS OF HIGH-STRENGTH TITANIUM ALLOYS Russian patent published in 2005 - IPC

FIELD: processes for making thin sheets of high strength titanium alloys by pack rolling.

SUBSTANCE: method for making sheets with ultra-fine grain structure suitable for super-plastic deformation at temperatures lower than 800°C comprises steps of producing initial blank with grain size of α-phase no more than 2 micrometers by hot rolling of forged or formed slab with percentage thickness h_bl /h _k = 8 -10, where h_bl - thickness of initial blank before pack rolling, mm; h_k - thickness of ready sheet, mm; cooling blank at rate 200 - 400°C/min. Further thermal mechanical working is realized at quasi-isothermic condition by hot rolling of pack of blanks in steel case along lengthwise and cross directions at turning by 90°. Rolling direction is changed after achieving total deformation degree in one direction in range 60 - 70%. Value of discrete reductions during one heating cycle is no less than 10% and for each next pass it does not exceed reduction value of previous pass. Temperature of each next rolling pass is no more than that of previous pass. Temperature of hot deformation of pack of blanks is set in range that is by 200 -300°C lower than temperature of polymorphous conversion.

EFFECT: possibility for producing large-size thin sheets with submicron crystalline structure and with necessary mechanical properties.

4 cl, 2 dwg, 1 tbl, 2 ex