Analysis of the Microstructure and Mechanical Properties during Inertia Friction Welding of the Near-α TA19 Titanium Alloy

The current research of titanium alloy on friction welding process in the field of aero-engines mainly focuses on the linear friction welding.Compared to the linear friction welding,inertial friction welding of titanium alloy still has important application position in the welding of aero-engine rotating assembly.However,up to now,few reports on inertial friction welding of titanium alloy are found.In this paper,the near-alpha TA19 titanium alloy welded joint was successfully obtained by inertial friction welding(IFW)process.The microstructures and mechanical properties were investigated systematically.Results showed that the refined grains within 15‒20μm and weak texture were found in the weld zone due to dynamic recrystallization caused by high temperature and plastic deformation.The weld zone consisted of acicularα′martensite phase,αp phase and metastableβphase.Most lath-shapedαs andβphase in base metal were transformed into acicular martensiteα′phase and metastableβphase in thermo-mechanically affected zone and heat affected zone.As a result,the microhardness of welded joint gradually decreased from the weld zone to the base metal.Tensile specimens in room temperature and high temperature of 480℃ were all fractured in base metal illustrating that the inertia friction welded TA19 titanium alloy joint owned higher tensile strength compared to the base metal.