The Effect Of Anneal Processing On The Properties Of SZA-4 New Zirconium Alloy Cladding Tube

With small thermal neutron absorption cross section,good corrosion resistance,high heat conduction and strength and excellent reduction property,zirconium and zirconium alloy is broadly applied in nuclear reactor as fuel cladding and core structural material,which affects the nuclear reactor's life and safety.To improve the comprehensive property of the fuel cladding became a key issue.This article studies the effect that annealing process put on SZA-4 alloy structure,mechanical and corrosion in order to seek a best alloy property by optimizing annealing process.Mechanical and structural property of SZA-4 alloy was studied through a series of annealing experiments between 440?580?.it showed that as the annealing temperature rises,SZA-4 alloy became partial recrystallized and fully recrystallized from stress relieved.The microstructure,elevated temperature tensile and CSR variations with annealing process.The microstructure is recrystallized between 480?and 530?,the mechanical properties undulate.The annealing process for stress relief and fully recrystallization can be determined by mechanical and structural property.After a 370-day long term corrosion test,samples taken from 12 types of annealing processes shows that final annealing can affect corrosion property.It presents a rather relevant trend in three different media.The corrosion weight gain on partial recrystallization samples and full recrystallization samples is quite similar,however,the corrosion weight gain on stress relief annealing samples is worse than both above.Because the content of niobium in SZA-4 alloy is similar to of in?-Zr,which is about0.29%?0.49%.After recrystallization annealing,the content of niobium in the 2^nd phase particles is higher than it in the matrix,however,the corrosion rate of the 2^nd phase particles is much slower than a-Zr matrix.By comparing the corrosion results,it is confirmed that the extrusion and intermediate annealing temperature do not affect the property of SZA-4 alloy cladding tube.Compared to long corrosion test result of zirlo and zr-4 alloy,SZA-4 alloy shows better corrosion property.The corrosion weight gain of SZA-4 fully re-crystallization sample is half of zirlo alloy and 8%of zr-4 alloy in a 360?/18.6MPa/0.01mol Li OH water solution and deionized water.The weight gain result in 400?/10.3MPa steam atmosphere is also better than zirlo alloy.While it shows worse result than zr-4 alloy after 160 days test.Generally,the corrosion property is better than zirlo and zr-4 alloy,which can satisfy the requirements of fuel cladding tubing for the 3^rd generation advanced passive PWR.