| Due to the diversification of its microstructure and phase transformation,structure?titanium alloy can have better mechanical properties matching,making it widely used in aerospace,marine,machinery and other industries.Alloys with different molybdenum equivalents and phase stability have different deformation mechanisms under different deformation conditions,which results in great differences in properties and also affects the alloy production process.In this paper,the metastable?titanium alloy Ti-3Al-8V-6Cr-4Mo-4Zr(TB9)alloy and the near?-type titanium alloy Ti-10V-2Fe-3Al(Ti1023)alloy are studied,and the metallographic microscope and scanning electron microscope,transmission electron microscopy,electron backscatter diffraction,X-ray diffraction are used,hardness test and room temperature compression test systematically studied the alloy deformation mechanism and its influencing factors,and obtained the following main conclusions:The room temperature deformation mechanism of TB9 alloy after solution treatment is dislocation slip.When the deformation of the alloy is less than 0.1,some soft-oriented grains preferentially open to single-slide.When the deformation is greater than 0.1,almost all the grains begin to show slip characteristics,and the phenomenon of multi-slip and cross-slip is obvious.The hardness value increases rapidly,and the“deformation hardening”effect is exhibited.The hardness value increases from the solid 258HV of alloy with solution treatment to 334HV.The main deformation mechanism of the alloy at different grain sizes and strain rates is still dislocation slip.After solution at 820?,the yield strength of the alloy is 885 MPa,which is 80MPa higher than that after solution at 760?.After compression at a strain rate of 0.7×10-2s-1,the yield strength of the alloy is 845MPa,which is 77MPa higher than that after 0.7×10-4s-1 compression.The"double yield"phenomenon occurs in the compressive true stress-true strain curve of the Ti1023 alloy with solution treatment.The main room temperature deformation mechanism is stress induced martensitic transformation.When the compression true strain is less than 0.1,the primary martensite laths in parallel are induced in the grain of the alloy.When the true strain is greater than 0.1,the laths gradually grow up and the secondary laths are formed.The hardness of the alloy increases from 236HV of alloy with solution treatment to 330HV.The main deformation mechanism of the alloy under different grain sizes and strain rates is still stress induced martensite transformation.After 900?solution,the induced stress of martensite and yield strength are 526MPa and 920MPa,which are 14MP and 38MPa lower than 820?,respectively.After compression by 0.7×10-2s-1,the induced stress of martensite and yield strength are 475MPa and 940MPa,which are increased by 90MPa and 107MPa respectively after compression of 0.7×10-4s-1.After solution below the phase transition point,Ti1023 alloy contains 28%primary?phase,and the main deformation mechanism is still martensitic transformation.The martensite forms a strong preferential orientation on the{0001}and{10(?)0}planes.The yield strength of the alloy decreases to 905MPa and the induced stress increases to560MPa compared with the solution above the phase transition point. |
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