Study On Isothermal Deformation Characteristics And Microstructure Evolution Of Flash Welded TA19 Alloy

As an important advanced material,titanium alloy plays an important role in the aerospace field.Nearα-titanium alloy TA19 is widely used in aircraft engines,casings,leaf discs and other components due to its good strong plastic fit.Flash welding is an emerging joining technology in the forming of titanium alloy components.It is more efficient and has better welding quality than traditional solid-state welding.It is especially suitable for the connection of large-sized structural parts.However,since the local temperature exceeds its phase transition point,the Widmansatten structure of the lamellae layer often appears at the welded joint,which seriously deteriorates the comprehensive performance of the titanium alloy weldment.Therefore,proper post-weld treatment is required to eliminate the Wei’s structure,optimize the welded structure,and improve the uniformity of the tissue in order to obtain excellent comprehensive performance.This paper takes TA19 flash weldment as the research object,and explores the influence of post-weld deformation heat treatment on welding structure control and weldment performance optimization.The deformation temperature（900⁹80°C）and deformation are studied by isothermal constant strain rate experimental system.（30,60%）and strain rate(0.01s^-11s^-1),on the deformation behavior and evolution of the welded structure,focusing on the evolution of the mechanical properties of the welded parts with different deformation,for high performance welding The manufacturing of the parts provides a technical reference.The main contents are as follows:1、According to the deformation characteristics of the welded structure under different deformation temperature and strain rate,the real strain of the weld position is predicted by finite element analysis in real time.Based on this,the thermal deformation constitutive equation of flash welding TA19 is established,and the corresponding Thermal processing diagram.The thermal processing map indicates that deformation unevenness and local flow are likely to occur as the strain rate increases,eventually leading to instability.2、The microstructure evolution characteristics of TA19 flash welded joints under different deformation temperature,deformation rate and deformation are studied.The results show that the increase of deformation temperature,the increase of deformation and the decrease of strain rate contribute to the dynamic recovery and dynamic recrystallization of materials.Occurs to promote the initial lamellar organization of the weld to complete the equiaxed and incompletely transformed tissue dissolution.After the heat treatment of the deformed welded joint,under the action of static recrystallization and diffusion,the equiaxed proportion of the lamellae structure is further improved,and the uniformity of the weld of the TA19 flash weld to base metal is realized.3、According to the evolution characteristics of the welded structure,two kinds of TA19 welded joints with typical microstructure were selected,and the influence of solid solution aging on the evolution and mechanical properties of welded joints and undeformed welded joints and matrix was explored,and the welded structure was further optimized.Studies have shown that the post-weld re-treatment achieves better control of the weldment than the original material,and its strength and plasticity are increased by 16%and 27.2%,respectively.Provides technical guarantee for the preparation of high performance,high quality,low cost titanium alloy weldments.