The Control On Microstructure And Properties Of CT20 Titanium Alloy

It was made eight different forging systems from three aspects, including thermal deformation degree; thermal deformation temperature and beta uniform heat treatment. Through comparing the relationship between microstructure and properties of three heating times of different forging system, we obtained the general rule of forging of CT20 titanium alloy; and got the best optimization of the forging process. In addition, this paper also studies the effect of forging process on microstructure and properties of large-sized bar cross-section. Every heating time and each forging system alloy tested tensile properties, Base on SEM analysis and metallographic analysis. CT20 titanium alloy plastic deformation mechanism is discussed.It was found that: The large-sized bar has different microstructure evolution among different part of bar cross-section, for that the alloy has different deformation and cooling rate. Microstructure and mechanical properties is the best on position of the 1/2R to 3/4R place through the cross section.As forging heating times, macroscopic metallographic microstructure of the alloy showed a uniformer and finer, microscopic metallographic microstructure of the alloy showed, Widmanstaten structure transformed into lamellar structure, equiaxed structure spheroidizing more fully, and tends to uniform. Forged at two-phase region, the microstructure is equiaxed or lamellar + equiaxed, Forged atβphase region, the microstructure is basket or basket + Widmanstaten structure. It can be found from tensile fracture surface that the sample forged at 960℃was brittle fracture, poor plastic; the sample forged at 920℃had plenty of toughening nests, which was deep and uniform, material plastic well. By testing the mechanical properties at low temperature, it found that CT20 titanium alloy has excellent low-temperature (20K) mechanical properties. Compared with room temperature mechanical properties, plastic slightly decreased, while the strength increased double times.And it found that as forging heating times increased, deformation degree increased. alloy plastics increased slightly, while the strength decreased rapidly. Comparatively, it is found that the forgings microstructure and mechanical properties of room temperature and low temperature achieve the best match at the condition of the second heating time, T3 scheme, that is 920℃, 20% deformation,βphase uniform heat treatment.