Technology Research On Large Size Ingots And Bars Of TC4 Titanium Alloy

TC4 is a typical two phases(α+β) titanium alloy which is the most reliable and being applied wildly. The big size bars(Φ200~Φ350 mm)of TC4 and its application has been investigated in this paper. The technology study and optimization on big size ingots(Φ710~Φ940 mm) and big size bars of TC4 have been done. The key technology is to assure the homogeneity of composition and microstructure, reduce the metallurgy defects, enhance the forging deformation and homogeneity of as-forged microstructure and reduce the manufacturing defects to improve the flow detection level.In the technology study of big size ingots, the reason of metallurgy defects in ingots has been discussed; for the positive segregation in TC4 Titanium alloy, the selection and adding ways of intermediate alloys has been optimized; single electrode mixing technology and vacuum plasma welding technology are used to produce consumable electrodes; in order to assure the homogeneity of the alloy elements ’distribution in electrodes, the proper melting technological ways and parameter are formulated.In the technology study of big size bars, the reason that existing bars cannot satisfy the requirement has been studied. Abandoning upsetting and stretching in small blanks,the technology of Solid forging in single big bars has been made. In this way, uneven deformation caused by upsetting and stretching repeatedly has been reduced; the bars ’length has been increased; the microstructure defects after forging has been decreased; the flow detection level has been improved.The research result provides the technological assurance for the production of the big size TC4 titanium alloy ingots and bars, which can satisfy the requirement in aerospace fields. It has an important significance in improving the research level and strength the defenses in our country.