Study On Stamping Properties And Pre-deformation And Annealing Process Of New Zirconium Alloy Sheet

Zirconium alloy has the characteristics of small thermal neutron absorption cross section,moderate mechanical properties,good processability and corrosion resistance,and is widely used as a key core component of nuclear fuel assemblies in nuclear power plants.The world’s nuclear reactors are developing in the direction of high fuel consumption,zero damage,and long life.Traditional zirconium alloys are difficult to meet the requirements,and the development of new zirconium alloys is urgent.In this paper,the domestic new zirconium alloy sheet strip for nuclear fuel assembly is taken as the research object.The combination of simulation calculation and process test is used to analyze the influence of pre-deformation and annealing on strip punching performance based on the analysis of microstructure and mechanical properties.The research results are expected to provide a theoretical basis for the adjustment of the new zirconium alloy strip manufacturing process and the optimization of matching corrosion resistance and punching performance.Firstly in this thesis,the microstructure and mechanical properties of the new zirconium alloy sheet are studied.It is found that the grain morphology of the strip is mostly equiaxed with a grain size of 1.39 μ m;the bimodal texture of the base is obvious,<0001>The crystal orientation is inclined in the vertical RD plane by about 30° in the TD direction,the <10(?)0> direction is parallel to the rolling direction,<11(?)0> vertical rolling direction,<11(?)0> The composition is more than <10(?)0>;the room temperature property of the strip shows obvious anisotropy,and the tensile fracture has ductile fracture characteristics.Secondly,this paper simulates the punching process of the new zirconium alloy sheet strip,and studies the influence of material parameters on the forming quality of the strip.It is found that the safety margin of the new zirconium alloy sheet strip is 7.5%,and the test piece actually punches.There is no rupture in the system,and the simulation is basically consistent with the actual punching result.In addition,the punching quality of the test piece is closely related to the hardening index of the thin strip,and the hardening index is improved,and the ultimate forming ability of the strip is enhanced;the hardening index(n)is At 0.18,the safety margin of the thin strip is 10%;the thick anisotropy coefficient(r)has an effect on the punching of the new zirconium alloy strip,but there is a certain limit;when the thick anisotropy coefficient is average (?) When less than 4.25,r increases the critical section in the left half of the forming limit diagram,increasing the forming abil ity,and also causes the wrinkling trend to move on the line,increasing the risk of wrinkling;when(?)is greater than 4.25,the new zirconium The influence of forming ability of alloy s heet strip is not obvious;the yield ratio increases,the maximum principal strain and thinning rate increase,the safety margin decreases,the yield is relatively small,which is favorable for punching;when the yield ratio is 0.62,the belt Material safe ty margin is 10 %.Finally,the pre-deformation and annealing experiments of the new zirconium alloy sheet strip were carried out.The effects of deformation and annealing temperature on the mechanical properties and microstructure of the strip were studie d.It was found that under small deformation conditions,the annealing temperature was changed and the new zirconium could be adjusted.The punching performance of the alloy sheet strip;the annealing temperature is increased,the yield ratio is decreased,and the n value is increased,which is beneficial to the strip punching;the n value and the yield ratio are the main material factors affecting the strip forming,and the small deformation condition Underneath,both the n value and the yield ratio are af fected by annealing,but it is not obvious whether it is affected by the amount of deformation.