Study On Technology And Microstructure And Properties Of 2195 Aluminum-Lithium Alloy Profile Produced By Spray Forming Ingot

With the development of aerospace industry,the demand for low-density and highstrength aluminum alloy materials is increasing.As one of such materials,Al-Li alloy is bound to be a development trend.This technology research is based on the domestic development needs of the space industry and the spray forming technology which is used to manufacture 2195 Al-Li alloy profile.As the Li element in Al-Li alloy is quite active,defects are prone to appear in the traditional DC casting process,which will affect the performance of Al-Li alloy.However,Al-Li alloy ingots are produced with the spray forming technology in this research,further studied for their extrusion process,heat treatment process and stretching process,and tested and analyzed with OM,TEM,XRD,DSC,flaw detection and performance measurement.A new production process of Al-Li alloy is thus being studied.The metallurgical quality of the spray-formed Al-Li alloy ingots is comprehensively evaluated by means of hardness,defect,macrostructure and hydrogen content detection.The results show that the macrosegregation of the ingot can be improved much by spray forming casting,as the maximum macrosegregation of Cu element,Li element and Ag element in the ingot are 0.11 wt.%,0.01 wt.% and 0.035 wt.%,respectively.The hardness of the spray-formed ingot can reach 77.1HB,which is close to that of extrusion state,as a result showing good mechanical properties.Though there isn't on-line hydrogen treatment equipment,the solid hydrogen content in this process is still low,i.e.0.172?g/g.So it can be seen that the spray forming process is of great help to the control of hydrogen content.The results of the AAlevelled flaw detection of the extruded bar further reflect that the sprayed ingot can achieve better metallurgical quality.The surface quality and properties of the products are studied with different extrusion speeds and temperatures.It is found that when extrusion temperature exceeds 370?,it will have little iMPact on mechanical properties.Based on the production management and process control management,the best extrusion technology is to set extrusion temperature as 430? and extrusion speed as no greater than 0.8 mm/s.The heat treatment process of profiles is studied through verification of the solid solution process and various tests of the aging heat treatment.The results indicate that the optimum quenching temperature,aging temperature,holding time is 505?,155?,and 36 h,respectively.While elongation is controlled in the range of 3.0% ~ 4.0% in the matched stretching process.After treated with the optimal process,tensile strength,non-proportional elongation strength and elongation of the profile can reach 583 MPa,540.5MPa,and 9.05%,respectively.The comprehensive mechanical properties are very good,which can fully meet the needs of the aerospace industry.The reproducibility of this process is confirmed through further industrialization verification,which is fully applicable to the production process requirements.Under industrial conditions,the mechanical properties of the products meet the standard requirements and are basically consistent with the experimental properties.