Abstract

Recycling of Zr-Nb-Sn-Fe scraps in castingenhances the price competitiveness of nuclear-grade Zr alloysand accordingly the energy from nuclear power plants.Increasing the fraction of scrap in casting of new alloy ingotsincreases the price competitiveness, but it aggravates thedeformability and mechanical reliability of cast alloys. In thisstudy, the effect of scrap ratio on the mechanical reliability ofZr-Nb-Sn-Fe alloys was studied. The increase of scrap fractionin casting increases the oxygen content in the ingot and nuclearcladdings fabricated from cast ingots. The increase of oxygencontent is caused by the surface oxide of scraps such as smallpieces of turning, chips, etc. Iron content was not found toincrease appreciably with the increasing fraction of scrapbecause scraps were well kept in the iron-free container. Themicrostructure of ss-cast Zr alloy with increasing fraction ofscraps displayed plate/or needle α phase and themicrostructural features were observed to be affected byincrease of scrap fraction. The strength increases withincreasing fraction of scrap, which can be attributed to theincrease of oxygen content. The ductility decreased slightly withincrease of scrap fraction. The strength increased at the expenseof ductility with increase of scrap fraction. In some ingots, ironoxide flakes were intentionally added to explore the effects ofiron oxide which may be added from the scarp storagecontainer. The alloys with the addition of iron oxide flakesexhibited the drastic decrease of the formability and exhibitedthe brittle fracture behavior during rolling. The increase ofoxide fraction increased the oxidation resistance because of highoxygen content the matrix may have prevented oxygen diffusioninto matrix.