| The key core components of nuclear fuel assemblies are composed of different inner and outer strips made of zirconium alloy sheet strip.Strip manufacturing technology is an indispensable part of the nuclear fuel assembly manufacturing system.In this paper,the domestically produced new zirconium alloy is used as the research object,and the grain size,second phase and recrystallization texture of the thin strip are characterized by the combination of tissue analysis,performance test and simulation calculation.Starting from the relationship between mechanical properties and forming properties,the maximum thinning rate,maximum principal strai n and safety margin are taken as the evaluation indicators.Based on the simulation of the punching process,study the influence factors of material factors,punching methods and process parameters on the shape quality and explore the influencing factors affecting strip punching.The research results are expected to provide technical support for the commercialization of new zirconium alloy strip punching and nuclear fuel assembly manufacturing.In the paper,the microstructure,mechanical properties and for ming properties of the new zirconium alloy were studied.It was found that the grain morphology of the thin strip was equiaxed,the size was small,and the average intercept was 2.70?m.The second phase particles are small in size and randomly distributed inside the crystal and at the grain boundaries,one being Zr-Nb-Fe particles and the other being Zr-Nb particles;In the RD-TD plane,there is a bimodal texture of the base surface which is biased toward the TD direction in the RD-TD plane,which are respectively<101?0>//RD direction and<112?0>//RD direction,the strength of the texture is similar;From the mechanical properties of yield strength,tensile strength,yield ratio and hardening index,the punching properties of the sheet strip in the RD direct ion are better than those in the TD direction.From the aspect of the thickness anisotropy coefficient,the punching performance in the TD direction is slightly better than that in the RD direction;the plane anisotropy?r is small,which shows that the plastic deformation caused by the various directions during the stripping process is relatively uniform,and the forming quality of the punched test piece is better.Secondly,the simulation study on the forming process of the new zirconium alloy is carried out.It is found that the punching method has an important influence on the forming quality of the test piece.In order to adapt to the change of the punching mode,the performance of the new zirconium alloy sheet strip needs to be carried out in the direction.Reasonable regulation.Under the conditions of transverse punching and longitudinal punching,no cracking occurred in the sheet metal forming specimens,but in comparison,the transverse punching effect was better than the longitudinal punching;In addition,the punching shape of the test piece is closely related to the material factors such as the thickness anisotropy coefficient,the hardening index and the Poisson's ratio of the thin strip.The mold gap,the blank holder force,the punching speed a nd the friction coefficient also affect the sheet metal forming.quality;When the thickness anisotropy coefficient is 5.675<rRD<7.675,the strip transverse punching effect is the best,and when the thick anisotropy coefficient is 5.57<rTD<6.57,the strip longitudinal punching effect is the best;when the hardening index is 0.10<n<0.18 With the increase of the hardening index,the strip punching and longitudinal punching effects are improved,and the safety margin is greatly improved when th e sheet metal strip is punched.When the Poisson's ratio??=0.377,the strip punching effect is best.The elastic modulus is not related to the strip punching;in the punching process factors affecting the forming quality of the strip,the influence of the mold gap is the most significant,and the second blanking force,the punching speed,and the friction coefficient have the least influence. |
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