Research On Deformation Behavior And Microstructure Evolution Of Hydrogenated Ti65 Alloy

Ti65 alloy is a new type of near-? type high temperature titanium alloy with high deformation temperature and high deformation resistance,making it difficult to process and shape.Hot hydrogen treatment technology can reduce the difficulty of processing titanium Ti65 alloy and improve the microstructure and mechanical properties of the alloy.In order to study the high-temperature flow behavior of Ti65 alloy and the influence of hydrogen on the high-temperature flow behavior of Ti65 alloy,a series of hightemperature compression experiments are designed.And based on the stress and strain data obtained from the compression experiment,the constitutive equations and hot processing maps of Ti65 alloys with different hydrogen content are established,which fills the gap in the research of Ti65 alloy hot hydrogen treatment.This paper also studied the microstructure evolution of Ti65 alloy with local hydrogenation after thermal deformation and vacuum removal of hydrogen,and for the first time explored the feasibility of forming titanium alloy gradient structure parts by local hydrogenation.First,the Ti65 alloy samples with different hydrogen contents were obtained through hydrogenation experiments.The phase transformation point test and microstructure observation of Ti65 alloys with different hydrogen contents were carried out by thermal dilatometer and a three-dimensional microscope with super depth of field.According to the results,a high-temperature compression experiment of Ti65 alloy with different hydrogen content was designed.According to the experimental results,it can be concluded that hydrogen can significantly reduce the high temperature flow stress of Ti65 alloy,improve the hot workability of Ti65 alloy,and at the same time promote dynamic recrystallization during deformation of Ti65 alloy,and improve its microstructure.Secondly,based on high-temperature compression experiments,the hyperbolic sine constitutive equations and hot processing maps of Ti65 alloys with different hydrogen contents are established in this paper.The established constitutive equation can describe the rheological behavior of the alloy at high temperature accurately.According to the established hot processing map,suitable processing windows for Ti65 alloys with different hydrogen content can be obtained.Finally,this paper developed a glass coating with good hydrogen barrier effect.By sintering a layer of coating on the end face of the Ti65 alloy sample,the radial local hydrogen was realized.The hydrogen content of the partial hydrogenation sample presents a gradient distribution,gradually decreasing from the outside to the inside.Through heating and heat preservation,high temperature deformation and vacuum hydrogen removal steps,different tissues can be formed in different parts of the partial hydrogenation sample.The organization gradually transforms from a lamellar organization to a spherical organization from the outside to the inside.The outer layer is a basket-wave organization,the inner layer is an isometric organization,and the intermediate transition layer forms a bimodal organization.