Characterization And Control Of Microstructure And Properties Of Linear Friction Welding Joint Of TC4/TC17 Heterogeneous Titanium Alloy

As one of the key components of aircraft engine,dual performance integrated blade-disc plays an important role in improving the working life and thrust-weight ratio of the engine,and has been widely used in the manufacture of advanced aircraft engine abroad.As a special welding method,linear friction welding technology has been widely used in the manufacture and repair of the whole blade disc because of its high quality,green and efficient technical characteristics.Based on the aeroengine performance of double integral semal manufacturing requirements,by adopting the method of linear friction welding technology,in view of the TC4,high performance of titanium alloy TC17 material,welding process is studied in joint forming,micro area organization characteristics and heat treatment after welding on the joint organization performance,obtained the linear friction welding of high strength,It provides technical support for t he design and manufacture of double performance integrated blade disc in China.By adjusting the welding process parameters,the influences of friction pressure and amplitude on the macroscopic forming of the specimen were studied.It was found that only when the medium frequency and high frequency pressure reached a certain value,the welding defects such as unfusion and holes in the microstructure of the interface could be avoided,and the good welding forming and the 100% bonding of the microstructure interface could be obtained.The effects of different heat treatment temperatures and holding time on the microstructure and properties were studied.It was found that the metastable ? phase in the weld zone and heat affected zone of TC17 side underwent diff erent degree of decomposition after heat treatment.With the increase of heat treatment temperature and holding time,the fine ?+? microstructure grew up continuously.As the heat treatment temperature increases and the holding time is too long,the number of ?-dispersed microstructure grows less.However,the acicular martensite formed by welding TC4 does not change significantly during heat treatment due to the presence of mainly ?-stable element.Through mechanical properties research found that when insu fficient pressure welding,the joint microhardness,large differences between different regions of and low friction pressure,room temperature tensile specimen fracture in the weld welding state,tensile strength than TC4 material is low,at the same time an insufficient elongation joint shape weaker fracture fault slag content,with lamellar tearing quasi cleavage fracture;When the welding pressure increases,with good heat treatment process,the welded joint can be strengthened to a certain extent,with good fusion,high microhardness and toughness equal to TC4 base metal,and the fracture is in the form of ductile fracture.