Research On Compressive Properties And High Temperature Deformation Behavior Of Ti-B20 High Strength ? Titanium Alloy

High strength ? titanium alloy has become an important aerospace construction materials due to its excellent deep hardenability,good hot and cold forming performance,and excellent corrosion resistance and other advantages.Because of its high strength,so that in the field of armor protection has become an important potential material.With the rapid development of aerospace industry,many countries carried out deeply research on the high-strength ? titanium alloy.In this paper,a new type of metastable ?-titanium alloy Ti-B20 is used as the research object.Its nominal composition is Ti-3.5Al-5Mo-4V-2Cr-1Fe-2Zr-2Sn.The effects of heat treatment on the microstructure and compressive properties of forged alloys were studied.The high temperature deformation behavior of the alloy was studied and the alloy plate was rolled according to the results of thermal compression.The microstructure and mechanical properties of the plate were studied.The as-forged Ti-B20 alloy is soluted at the??+??field and ? field,and the plasticity of the alloy was significantly improved after the solution treatment,but the strength decreased a little.Followed by the solution treatment of the alloy were single-stage aging and two-stage aging.The compressive strength of the alloy was 1854.3MPa and the compressive strain was 25.7% under the condition of 870?/0.5h + 550 ?/8h heat treatment,and the strength was matched with plasticity.The effects of heat treatment on the dynamic properties of the alloy were studied.Different compositions were obtained under different heat treatment conditions.We obtained the organization with equiaxed tissue E1 at 790?/0.5h,equiaxed tissue E2 at 870?/0.5h,with bimodal tissue B1 at 790?/0.5h + 550?/8h,with doublet structure B2 at 790?/0.5h + 350?/4h + 550?/8h,with lamellar tissue L1 at 870?/0.5h + 550?/8h,with lamellar tissue L2 at 870?/0.5h + 350?/4h + 550?/8h.The high temperature deformation behavior of Ti-B20 alloy was studied by Gleeble 1500 thermal simulator.The rheological stress of Ti-B20 alloy increased with the decrease of deformation temperature and the increase of strain rate.The recovery mechanism of the alloy is mainly DRV at low temperature?750?-830??and CDRX at high temperature?830?-910??.The degree of DRX increases with the increase of deformation temperature and the decrease of strain rate.The average thermal activation energy of Ti-B20 alloy is Q = 298.61 KJ / mol.The constitutive equation of Ti-B20 alloy is: ???=e^28.36[sinh?0.007526??]^2.78exp??-298610/RT?.The thermal processing map of the alloy at ? = 0.4,? = 0.5 and ? = 0.6 is plotted.According to the thermal processing map,the optimum hot working range of the asforged Ti-B20 alloy is: deformation temperature is between 790?-810? and 860?-910?,the strain rate is 0.01s^-1.According to the results of the thermal processing map,the as-forged Ti-B20 alloy was rolled in the?? + ??filed and ? filed,respectively,and the strength of the alloy rolled in the?? + ??filed is better than in the ? filed,and its tensile strength is 1103 MPa,and the elongation is 7%.