Study On Hot Working Technology Of TC4-DT Titanium Alloy

Titanium alloy has excellent comprehensive mechanical properties,is the key material to create new aircraft components.With the development of aviation industry,aircraft components on titanium alloy damage tolerance performance requirements are increasingly high,durability and damage tolerance design has become a modern aircraft common design criteria.TC4-DT titanium alloy as China’s self-developed damage tolerance type titanium alloy,the large-scale aerospace components made of them are mainly made by die-forging and with proper heat treatment to obtain good structure and properties.In this paper,TC4-DT titanium alloy was used as the research object,and the hot deformation behavior of the alloy at the temperature of 850~1040℃ and the strain rate of 0.005~0.5s-1 was studied in Gleeble thermal simulator test machine to obtain a flow stress curve.The effect of deformation parameters on the flow stress of the alloy was analyzed.The total strain constitutive equation and processing map of TC4-DT titanium alloy were established through using the flow stress curve.And the influence of deformation parameters on the microstructure of the alloy was analyzed.The relationship between isometric α phase content and temperature was established.The effect of β single phase heat treatment on the microstructure and mechanical properties of TC4-DT titanium alloy was studied.The effects of microstructures on the mechanical properties(especially fracture toughness)of the alloy at room temperature were analyze.The tensile fracture of equiaxial tissue and lamellar tissue and the effect of the thickness of α slice on the tensile fracture in the lamellar structure was analyzed by SEM scanning electron microscopy.The forging forming of a TC4-DT titanium alloy die forging was numerically simulated by DEFORM-3D finite element software,and the effects of initial forging temperature on the temperature field,strain field and forming load of the forging were analyzed.According to the forming simulation results,the trial of forging was carried out and the isometric α phase content of the forging was predicted.The forgings were subjected to quasi-β heat treatment and the mechanical properties of the trial forgings were tested and evaluated.