Experimental Study On High Temperature Toughness Fracture Criterion Of Austenitic Stainless Steel Based On Critical Cavity Expansion Ratio Theory

Austenitic stainless steel is widely used in modern industrial production and people’s daily life in many areas,with its excellent performance and widely recognized.In the production process of Austenitic stainless steel is easy to produce cracks and other defects,thus affecting the quality of follow-up processing.In the actual production,the toughness damage theory can be used to predict the crack initiation region of the material and optimize the processing technology.Therefore,it is necessary to study the damage failure of austenitic stainless steel.In this paper,the Austenitic stainless steel TP321 is selected as the research object,and the application of the critical hole expansion ratio theory of toughness material at high temperature is discussed.In ductile materials,the nucleation,growth and polymerization of micropores are an important mechanism leading to the plastic damage and damage of metallic materials.And the theory of critical hole expansion is that the damage process of ductile material under this mesoscopic condition is manifested in macroscopic form.And the critical hole expansion ratio parameter V_GC is determined to materialize the fracture point of the material toughness damage.In order to obtain the critical hole expansion ratio parameters of TP321 material at high temperature,the high temperature tensile test was carried out on Gleeble3800 thermal simulation testing machine,and the TP321 material was obtained under different temperature and different strain rate True stress-strain curve.According to the obtained test results,the finite element simulation is carried out.In the simulation results,the equivalent plastic strain value and the stress triaxiality value of the specimen fracture moment,the moment of fracture of the specimen are read.The critical hole expansion ratio parameters of different samples were calculated.The variation law of critical hole expansion ratio with temperature and strain rate is established.The applicability of the critical hole expansion ratio theory to the austenitic stainless steel at high temperature is verified.A material constant can be used to predict the initiation of TP321 material at high temperature.The critical hole expansion ratio The linear relationship between parameters and temperature.