Friction weldability of ultrafine-grained titanium grade 2

Abstract

The paper presents the results of an experimental study of the friction weldability of Titanium Grade 2 with ultrafine-grained (UFG) microstructure obtained by hydrostatic extrusion and rotary swaging (HE+RS). High-speed friction welding with different rotational speed (n) values was used as a joining method. The best properties were obtained for n=7000 rpm. Metallographic observations confirmed the formation of a continuous friction joint with a changed microstructure of the base material in the thermal-mechanical affected zone (TMAZ) and a friction weld (FW). The results of the mechanical properties showed the greatest decrease in hardness in the TMAZ. The friction welded joint had an 18 % lower tensile strength value than initial state UFG Titanium Grade 2 after the HE+RS process (with UTS=1050 MPa).

Keywords

• UFG
• Recrystallization
• Solid-state welding
• Titanium alloys
• Severe plastic deformation