Process for welding parts by linear friction and heat treatment

A process for welding a first part and a second part, said welding process comprising:

• a linear friction welding step during which the first and second parts are rubbed against one another in a linear movement;
• a first cooling step during which the temperature of the first and second parts welded by linear friction is reduced to ambient temperature;
• a heating step during which the first and second parts welded by linear friction are heated to a temperature above a temperature of transition between a two-phase α-β field and a single-phase β field of the material constituting the two parts such that the material of the first and second parts passes from a two-phase α-β field to single-phase β field;
• and
• a second cooling step during which the temperature of the first and second parts thus heated is reduced to ambient temperature such that α phase precipitates in a lamellar fashion in the β phase, so as to obtain a lamellar α phase in a β matrix,
• wherein the first part and the second part are made of titanium alloy.