Application Research Of TC11 Titanium Alloy Electron Beam Fuse Additive Composite Manufacturing

As the advantages of additive manufacturing technology become increasingly apparent,the technology is increasingly used in ground manufacturing of spacecraft.Titanium alloy,as an ideal aerospace material,has been used in space station,deep space exploration,carrier rocket,satellite and other fields.In order to solve the problem of high cost of additive manufacturing of large titanium alloy structural parts,the compound manufacturing method of"additive+forging"was proposed based on the advantages of rapid prototyping of additive manufacturing and high precision of substrates manufacturing.Based on the manufacture of large TC11 alloy structural parts of nozzle,the technology and properties of electron beam fuse additive composite manufacturing TC11 alloy parts were studied.The orthogonal test method was used to analyze the relationship between the process parameters and the forming coefficients.By fitting the nonlinear regression model and analyzing the coupling influence of process parameters,the process parameters under the optimized forming coefficient were obtained.The microstructure of fusing metal was observed for metallographic analysis.The macroscopic microstructure showed that the columnarβgrains grew in epitaxial mode from the bottom of the molten pool.In EBRM process,columnarβgrains grow epitaxially along the direction at a certain angle with the vertical direction.The evolution process of microstructure is as follows.liquid metal→βphase→α′/αphase transformation would happen in pool area.α→β→α’/αphase transformation would happen in the heat-affected region.The multiphases and multilayer TC11 titanium alloy cladding body was formed by optimized process parameters.Through metallographic analysis,spectral analysis and other test technologies,organization and chemical composition of the cladding were characterized.It is found the cladding structure characteristics of large columnarβgrains growing from melt the bottom along the height direction through multiple cladding layer.The Widmanstatten structure of cladding metal is found and the ratio of length to width decreases with the increase of cladding height.After the double heat treatment,the microstructure of the cladding body was improved,and approximately double/triple microstructure appeared in the lower part of the cladding body.The mechanical properties of multi-channel and multi-layer TC11 titanium alloy cladding body were tested.It has a high Al element at interface content and leads to poor plasticity and toughness.Under different process parameters hardness and strength of cladding TC11titanium alloy differ hardly.Plastic of cladding is lower than forging industry standard when the beam is 50m A or 80.The mechanical properties of EBF³ TC11 titanium alloy were characterized by high strength and low plasticity.Under the conditions of beam flow of 20m A,moving speed of 180mm?min^-1,wire feeding speed of 15mm?s^-1,and parameters of elliptic scanning mode,the strong plasticity of all parts of the specimens obtained by electron beam fuse composite additive manufacturing reached the forging industrial standard and met the production requirements.According to the scheme experimentally optimized of"forging+additive manufacturing"TC11 titanium alloy,the parts of the actual products meet the following indexes:tensile strength≥1030MPa,yield strength≥885mpa,post-fracture generation rate≥8%,section shrinkage≥23%,impact toughness≥29.5 J?cm^-2,320HBW≤hardness≤370HBW,and reach the performance indexes of GJB2744a-2007.The parts manufactured according to this process plan are qualified in ultrasonic inspection and meet the requirements of hydrostatic test.