Thin parts made of β or quasi-β titanium alloys; manufacture by forging

1. A non-axially symmetrical manufactured part having a thickness less than 10 mm, made of a quasi-β titanium alloy, and having a core microstructure comprising whole grains having a slenderness ratio greater than 4 and an equivalent diameter lying in the range of 10 μm to 300 μm, wherein the whole grains comprise lens-shaped forms, and non β-parts within the whole grains are α-needles, the manufactured part being made by a process comprising:

obtaining an enameled blank;

where necessary, transforming said blank into a long part of equivalent diameter less than 100 mm;

forging said long part with a final heating operation carried out at a temperature above a β transition;

quenching said forged long part; and

tempering said quenched forged long part.

2. The manufactured part according to claim 1 , comprising a blade for a turbomachine compressor.

3. The manufactured part according to claim 1 , wherein the quasi-β titanium alloy is a Ti 17 alloy (TA 5 CD 4 or TiAl 5 Cr 2 Mo 4 ).

4. The manufactured part according to claim 1 , wherein said forging comprises at least two heating operations, the first to a temperature that is below or above the β transition, and the last to a temperature that is above the β transition, the reduction ratio on each heating operation being greater than or equal to 2, and the forging speed lying in the range of 1 s −1 to 1×10 −5 s −1 .

5. The manufactured part according to claim 4 , wherein said forging comprises first and second heating operations that are independently above or below the β transition, and a third heating operation that is above the β transition.

6. The manufactured part according to claim 4 , further comprising:

re-enameling the part between two heating operations.

7. The manufactured part according to claim 1 , wherein a forging matrix is maintained at a temperature lying in the range of 100° C. to 700° C.

8. The manufactured part according to claim 1 , wherein quenching is implemented under conditions which induce a cooling speed that is less than or equal to the speed induced by quenching in a bath of oil.

9. The manufactured part according to claim 1 , wherein said tempering is implemented at a temperature lying in the range 620° C. to 750° C. for a period lying in the range 3 h to 5 h.

10. The manufactured part according to claim 1 , wherein:

said blank is made of Ti 17 alloy (TA 5 CD 4 or TiAl 5 Cr 2 Mo 4 );

said forging comprises a first heating operation at a temperature less than or equal to 840° C.±10° C. or at a temperature greater than or equal to 940° C.±10° C., and a second heating operation at a temperature of 940° C.±10° C.;

said quenching is implemented on a matrix and then in still air; and

said tempering is implemented at 630° C. for 4 h.