Influence of Microstructure on Strength and Ductility of TC29 Titanium Alloy
The TC29 titanium alloy was subjected to deformation treatment in the two-phase and single-phase regions respectively,followed by two kinds of heat treatments of annealing and solid solution aging.The effects of different processes and microstructures on the strength and ductility of TC29 titanium alloy were studied.The results show that the alloy undergoes deformation in the two-phase zone,and after annealing or solid solution aging treatment,the microstructure presents a typical duplex microstructure.After deformation in the two-phase zone and solid solution at 850℃and aging treatment,the micrometer level secondary α phase in the matrix disappears,and a large amount of nanometer level secondary α phase precipitates.After single-phase deformation and solid solution aging treatment,the microstructure mainly consists of layered α phase,and a large amount of nanoscale secondary α phase precipitates in the matrix.The deformation specimen of the two-phase zone treated by solid solution aging has a higher tensile strength at room temperature with the increases of solid solution temperature,reaching a maximum of 1471 MPa.The impact toughness of the deformed sample in the two-phase zone after annealing can reach up to 58.8 J/cm2.The fracture toughness of the single-phase deformation specimen treated with solid solution aging is the highest,reaching 73 MPa·m1/2.The sample after deformation in the two-phase zone presents cleavage fracture,with brittle transgranular fracture as the main mode of fracture and a small number of pores visble.After deformation in the single-phase zone,the sample presents a mixture of cleavage and ductile dimples,with a large number of tearing edges,pores,and secondary cracks.
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