Ti

2

AlNb alloy was welded by inertia friction welding. The microstructure changes of welded joints under welded condition and after different heat treatments were analyzed. The influence of different heat treatments on the microstructure of inertia friction welded joints of Ti–22Al–25Nb alloy was studied. The results show that the Ti–22Al– 25Nb alloy welded joint without defect and with weld in good condition can be obtained by inertial friction welding. The change of the number and size of O phase in the welding zone is determined by the temperature and duration of heat treatment. However

compared with the change of duration

the change of temperature during heat treatment has a more remarkable influence on O phase. After heat treatment at temperature between 780℃ and 850℃

the growth range of O phase in the welding zone is small

and the size after growth is still far smaller than that of the base material. The evo

lution of O phase in thermo-mechanically affected zone is the same as that in welding zone. With the increasing of heating temperature and prolonging of heating time

O phase in HAZ coarsens

while α

2

phase is of no change.