Study On The Autofrettage Damage Of The Ultra-High Vessel

The ultra-high vessel is widely used in all kinds of fields.It is the indispensable andkey equipments.It drives the development of high press,ultra-high press technique.Auto-frettage technique is studied more and more thoroughly and it is the key aspect of ultra-highvessel's design.The purpose of autofrettage technique is to obtain autofrettage residualstress.And the accurate calculation of residual stress is the key of it.In accordance with this problem,many scholars research much about autofrettagetheory.However,these theoretic models think the subject investigated as un-damage defor-mable solid and neglect the fact that the essential of autofrettage residual stress is thatdamage cumulation.Hereof,the paper tries to investigate the autofrettage damage mechanism of ultra-highvessel in view of damage mechanics.By damage mechanics theory,damage variable is usedto describe autofrettage theoretic deduction from autofrettage technique essential.Based ondamage mechanics ,the mechanism that the autofrettage ultra-high vessel brings damage isresearched.Firstly,this paper gives a detailed summary of the development of the ultra-highvessel,the development and the application of autofrettage technique,and the damage the-ory of the ultra-high vessel,etc.The researchful value of the paper is confirmed.Secondly,based on the requirement of research and combining autofrettage damage of ultra-high vess-el,the paper briefs basic theory of damage mechanics:compare damage mechanics withfracture mechanics,analyze the damaged forms of ultra-high vessel.Next,based onsummarizing kinds of autofrettage theoretic models ago,the paper introduces effectivestress' conception in accordance with the autofrettage damage mechanism of ultra-highvessel.On the basis of autofrettage vessel's characteristic, autofrettage damage mechanicsmodel is set up.The formulas for calculating the autofrettage damage press,critical damagepress,critical damage radius,outer-wall's annular strain,autofrettage residual stress are obt-ained based on autofrettage damage mechanics model.Finally,the autofrettage damage me-chaincs model is validated based on autofrettage experiment data of material 25Cr2MoV.The calculating result of model is more approaching to experimental resultand more precisi-on than ideal elastic-plastic model and two-way linear hardness model.Compared withtwo-way linear hardness model,the model is characterized with being simple and easy tocomprehend.The research shows that the thought and method that research autofrettage damage ofultra-high press vessel are proper and they have certain significance for studying anddesigning ultra-high press vessel,processing technique ,maintain and inspecting run ofautofrettage devices.