METHOD OF THERMOMECHANICAL TREATMENT OF ITEMS FROM TITANIUM ALLOYS Russian patent published in 2012 - IPC C22F1/18 

FIELD: metallurgy.

SUBSTANCE: method of thermomechanical treatment of items from titanium alloys involves thermomechanical treatment which is performed at twelve stages; at that, at the first stage there performed is heating to temperature of (T_pt+200÷T_pt+270)°C, deformation which involves four stages at cooling down to temperature of (T_pt+70÷T_pt-100)°C with change of deformation direction through 90° at alternation of shrinkage and drawing with deformation degree of 30÷60% at each stage; the second stage involves heating to temperature of (T_pt+120÷T_pt+170)°C, four stages of deformation at cooling down to the temperature of (T_pt-50÷T_pt-110)°C with the change of deformation direction through 90°C at alternation of shrinkage and drawing with deformation degree of 30-60% at each stage; the third stage involves heating up to temperature of (T_pt+20÷T_pt+70)°C, four stages of deformation at cooling down to temperature of (T_pt-70÷T_pt-140)°C with the change of deformation direction through 90°C at alternation of shrinkage and drawing with deformation degree of 30÷60% at each stage; the fourth stage involves heating up to temperature of (T_pt-20÷T_pt-40)°C, deformation with degree of 15-60% at cooling down to temperature of (T_pt-100÷T_pt-140)°C; the fifth stage involves heating up to temperature of (T_pt+70÷T_pt+90)°C, deformation with degree of 30-60% at cooling down to temperature of (T_pt-40÷T_pt-90)°C; the sixth stage involves heating up to temperature of (T_pt-20÷T_pt-40)°C, deformation with degree of 20-40% during cooling down to the temperature of (T_pt-60÷T_pt-100)°C; the seventh stage involves heating up to temperature of (T_pt+20÷T_pt+50)°C, deformation with degree of 30-60%) during cooling down to temperature of (T_pt-40÷T_pt-70)°C; the eighth stage involves heating up to temperature of (T_pt-20÷T_pt-40)°C, deformation with degree of 20-60% during cooling down to temperature of (T_pt-60÷T_pt-100)°C; the ninth stage involves heating up to temperature of (T_pt+30÷T_pt+70)°C, deformation at rolling with degree of 40-70% during cooling down to the temperature of (T_pt-70÷T_pt-170)°C; the tenth stage involves heating up to temperature of (T_pt-20÷T_pt-40)°C, rolling deformation with degree of 30-50% during cooling down to the temperature of (T_pt-100÷T_pt-200)°C; the eleventh stage involves heating to temperature of (T_pt-70÷T_pt-170)°C with exposure during 15-60 minutes, air or water cooling; the twelfth stage involves heating up to temperature of (T_pt-270÷T_pt-470)°C with exposure during 5-15 hours, where T_pt - polymorphic transformation temperature; at that, deformation direction through 90° is changed from two to four times starting from the fourth stage and ending with the eighth stage.

EFFECT: method of thermomechanical treatment provides the use of titanium alloys at low temperatures and at high stresses at biaxial tension and allows improving its operating reliability.

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