Effect Of Hot Working Processing On Microstructures And Mechanical Properties Of TC4-DT Alloy

Effects of thermal deformation processing and heat treatment on the microstructures and mechanical properties of TC4-DT titanium alloy, a new α+β alloy with moderate strength and high toughness developed in China were researched. By using SEM and optical microscope, the effects of microstructures on mechanical properties under various process were investigated.The results indicated that as hot working in α+β region with the increase of the hot deformation ratio, the size and content of primary a phase, the thickness and aspect ratio of secondary a phase varied. The type of microstructure did not change obviously after hot working in α+β region and α/β-solution treatment followed by aging, which mainly displayed the change of contents and sizes of primary equiaxed a phase and secondary a phase. Hot woking in β region, the higher the deformation temperature was, the bigger a colony was. When the alloy was solutionized in α+β region, the deformation processing and heat treatment determined the tensile properties. With the increase of the deformation ratio, the strength and ductility increased.High impact toughness was obtained by deformation in β region. After deformed below the transus temperature, impact toughness decreased. Best matching between strength and ductility in TC4-DT alloy was achieved after homogenized in β region and forged in α+β region, deformed at950℃with80%deformation ratio followed by heat treatment with930℃/1h AC+540℃/6h AC.