Research On The Hoop Tensile Properties Of Austenitic Stainless Steel Cladding Tube

Cladding tube is the first important safety barrier in the reactors,which contain fission gas in service environment and bear the mechanical interaction between pellet and cladding,the deformation main acts on the hoop direction of the cladding tube.The traditional pipe evaluation method can't be applied to the cladding tube.In this paper,316 Ti austenitic stainless steel was used as the research object.Firstly,the simulation and the hoop tensile test were used to optimize the size and friction coefficient of the specimen.Then the experimental study on the effect of temperature and tensile rate on the mechanical properties of 316 Ti stainless steel cladding tube were carried out.The conclusions were as follows:The factors influencing the hoop tensile of cladding tube were simulated by Abaqus finite element software,and the stress and strain distribution of different gauge length and friction coefficient were analyzed.The results showed that the stress distribution was more uniform when the width of the specimen was 2 mm,it was helpful to prevent the stress concentration,and the maximum stress of the gauge section increased with the increase of friction coefficient.Then the effect of different gauge length and lubricant on the test were analyzed by using a three-piece tooling test.The results showed that the width of the gauge section had little effect on the strength,but the specimen with the width of the gauge section of 2 mm showed better plasticity and the strength of the specimen increased with increase of frictional force.So graphite should be used as the lubricant for the ring tensile test.The hoop tensile tests of 316 Ti stainless steel at different temperatures and tensile rates were carried out according to the optimized sample size and lubricant options.The results showed that the tensile strength and yield strength decreased with the increase of temperature at different tensile rates,and the deformation decreased first and then increased with the increase of temperature.The dynamic strain aging(DSA)phenomenon happened under different tensile rate,and there was a DSA sensitive temperature range.With the increase of the tensile rate,the DSA sensitive temperature range had the tendency to move to high temperature.Through the microstructure analysis and the calculation of the activation energy of solute atom diffusion,it was considered that locking of dislocations by C and N interstitial solute were the essence of the DSA phenomenon.The results of this study provides a reference for the study of the hoop properties of 316 Ti austenitic stainless steel cladding,and provide theoretical data for the design of lead-based reactor in China.