Research On Common Technology Of Quasi-? Forging Of TC18 Titanium Alloy Forgings

With the rapid development of my country's aerospace,TC18 titanium alloy,as a high-strength,near-beta titanium alloy,is widely used in the manufacture of main load-bearing structural parts of aircraft.The alloy usually hopes to obtain excellent mechanical properties for forgings by the quasi-? forging process;the quasi-? forging deformation of TC18 titanium alloy has an important influence on its microstructure and properties.Too large or small deformation will cause the final performance to be unqualified,but in There is no clear definition of the relationship between the amount of deformation and the structure and performance in practical applications.At the same time,due to the lack of generalization and summary of the common technologies related to the quasi-? forging of the same type of structural parts,the product development cycle is longer.Therefore,this paper uses a U-shaped cross-section forging to design the quasi-? forging process and produce the trial production to obtain the test results,study the relationship between the different quasi-? forging deformation and the structure and properties,and obtain the best deformation that optimizes the comprehensive mechanical properties.The general technology related to TC18 titanium alloy quasi-?forging is studied with typical rib structure.The main research contents and conclusions of this paper are as follows:?Taking an aerospace titanium alloy forging as an example,the quasi-? forging process was designed and optimized.Aiming at the small deformation zone produced by the side wall of the U-shaped forging,a pre-formed structure of the outer side wall wave surface was proposed and designed;Quasi-? forging deformation uniformity is the optimization goal.After optimization,the equivalent strains of the three typical cross-sections in the good deformation zone account for 81.4%,89.3%,and 83.8%,respectively,which are 32.6% and 83.8% higher than before optimization.21.4%,34.3%;At the same time,the influence of different pre-forging structures and different forging process parameters on ? forging forming was analyzed and summarized,and the best forging process parameters were obtained.?According to the test results after production trial production,the microstructure and properties after forging were studied,and the relationship between the quasi-? forging deformation and the mechanical properties and microstructure was analyzed,and the optimal deformation range was 27%?32%;at the same time passed Fitting analysis shows that the strength,plasticity,and deformation are linear within a certain range.For every 10% increase in deformation,the strength will increase by about 13 MPa,the elongation will increase by about 0.6%,and the reduction of area will increase by about 2.5%;impact toughness It also increases with the increase of deformation,and the fracture toughness decreases with the increase of deformation.?The relationship between the internal structure and deformation after ? forging is obtained by SEM analysis.With the increase of deformation,the original coarse ?grains are gradually broken,and are squashed and elongated along the metal deformation direction,and the original ? grains gradually change.The small,continuous grain boundary ? gradually transforms to the discontinuous grain boundary ?,in a chain-like arrangement,the intragranular flake ? gradually becomes uniform and fine,and the thickness of the flake ? also decreases.?According to the optimal deformation range,taking the typical rib structure of titanium alloy forgings as an example,the common technology of TC18 titanium alloy ?forging is studied,and the design rules of webs and ribs of pre-forgings are analyzed and summarized.The analysis of variance is used to obtain The design rules for the transition fillets of the ribs with different rib width ratios and different widths and the matching relationship between the transition fillets of the pre-forgings and the final forgings are presented;for the delamination phenomenon of the web surface and the smallness of the high-thick ribs The deformation zone proposes an improvement method for the wave surface structure.