LAUSR

Abstract The last decade has seen several attempts to introduce bioresorbable prostheses in order to reduce the number of surgeries, but all the potentially interesting metallic alloys suffer of poor mechanical or chemical resistance. Zinc alloys are attracting more attention for producing temporary prosthesis devices thanks to their bioabsorbable characteristic in human environment, since they present a suitable corrosion resistance to human fluids. However, at the same time, they have extremely poor mechanical properties that make them still unsuitable for such applications. One possible way to increase mechanical performances is to refine the material grain using Severe Plastic Deformation (SPD) processes that can be traditionally used to obtain such refined microstructures through the application of high deformation rates under complex stress states. The paper focuses on the feasibility of using the backward tube flowforming process to obtain a significant grain refinement (below 1 µm) when applied to pure zinc alloy in order to increase its mechanical resistance to values suitable for load bearing temporary prostheses, starting from a 287 µm grain size material. A numerical FE simulation was adopted to understand the strain during the process while the influence of the process parameters, namely the reduction per pass, the mandrel speed and the feed rate, on the microstructural characteristics and related mechanical properties are shown and discussed.