TA15 titanium alloy pipe specimens were heat treated in the temperature range of 750-1050 ℃ for 1 h,and then air cooled.The effect of different heat treatment temperatures on microstructure and mechanical properties of TA15 titanium alloy pipe was studied by means of optical microscope,electronic universal testing machine,and pendulum impact testing machine.When the heat treatment temperature rises from 750 ℃ to 850 ℃,αp has no significant change,while the secondary α phase lamellae are coarsened.As the heat treatment temperature further increases to 950 ℃,the number of αp decreases,the equiaxed degree increases,and secondary α phases completely transform to high temperature β phase,during further cooling,the β transformation phases re-precipitate.When the heat treatment temperature is further increased above 1000 ℃,the microstructure transforms into a typical Widmanstätten structure.Heat treatment below the phase transition point(＜1000 ℃)results in a good match between strength and plasticity.As the heat treatment temperature increases,strength decreases and plasticity increases.The optimal match between strength and plasticity is reached when heat treated at 850 ℃.With the increase of heat treatment temperature,the impact property shows a trend of first increasing and then decreasing,among which the impact property is the best after heat treatment at 900 ℃.
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