Effects Of Heat Treatment On Microstructures And Properties Of A New Type High Strength Beta Titanium Alloy

Beta titanium alloys has become the ideal selection for ultra-high strength titaniumalloy because of their advantages of high age strengthening effect, excellent match ofstrength and toughness, deep hardening. A new type beta titanium alloys was researchedin this paper. Study the influence of two different types of heat treatment process on themicrostructure and mechanical property of the alloy. The microstructure,macrofractography and tensile property at ambient temperature after solution and agingtreatment and direct aging after hot rolling was analysesed by OM, SEM, TEM, XRDand Electronic tensile test machine. Discussing the characteristics of agingstrengthening of the alloy in different heating processing and explore the best heatingprocessing for the alloy from the point of view of thermodynamics and dynamics.The transformation temperature of the alloy was measured which is705±5℃inexperiment. The solution treatment was done with different temperature and coolingmethods nearby the transformation temperature, the results shows that we can get singleequiaxial β phase above the transformation temperature, otherwise separate out α phasewhich are short rod-like and granulate on β matrix under the transformation temperature,However, the influence of cooling methods to the structure of the alloy is small.The study found that the tensile strength will increase as the solution temperaturerises, the tensile strength and plasticity were both preferable at720℃, when the solutiontemperatures continues to rise, the tensile strength will come down. The best solutiontemperature is720℃. The strength and hardness of the alloy increased and the plasticitysignificantly decreased with the aging temperature decreased after720℃solution treatment. The tensile strength can reach above1430MPa while the ductility was6.74%with the aging temperature400℃for12hours, and the strength and plasticity is goodmatched at440℃aging. The strength and plasticity match was good at720℃solutiontreatment with water-cooling and440℃aging treatment, the tensile strength is1411.5MPa、yield strength is1297.5MPa、elongation is11.28%、reduction of area is41.25%.The study which based on the microstructure and properties of alloy found that thehardness and strength after direct aging increased with the temperature decreased, onthe contrary the ductility and percentage reduction of area increased quickly, thehardness reach to maximum after aging for10hours. The tensile property of the alloy atambient temperature of the alloy was excellent after440℃direct aging about10hours,the tensile strength is1472.5MPa、yield strength is1376.6MPa、elongation is9.36%、reduction of area is38.15%. The combination property was higher than the besttechnological parameters of solution and aging treatment.