Repetitive corrugation and straightening effect on the microstructure, crystallographic texture and electrochemical behavior for the Al-7075 alloy

Abstract

Anti-corrosion susceptibility is one of the top criteria for selecting metallic materials for several industrial applications. This work studies the corrosion performance on an Al-7075 alloy obtained by Repetitive Corrugation and Straightening (RCS). This processing method generated a microstructure formed by randomly distributed micro-, submicro-, and nano- metric grain sizes. The samples exhibited a drop in corrosion resistance for a longer duration in the electrolyte and higher deformation. However, the samples processed by RCS showed better electrochemical stability in comparison with the non-deformed condition. The improvement of electrochemical stability could be associated with the particular microstructure generated during the RCS process.

Heterostructured Materials by Severe Plastic Deformation: Overview and Perspectives

“…40) It is also common to obtain wide grain size distributions and non-equiaxial grain morphology after RCS processing. 35,118,119) Owing to this, RCS can provide heterostructured materials with multimodal grain size due to the heterogeneous nature of the deformation at the first pass. 72) Multimodal grain size distributions after RCS can be encouraged by the die geometry and by avoiding the 90°r otation between passes.…”

“…120) Examples of multimodal structures have been widely reported in the literature. 119,[121][122][123][124][125][126] The synergistic performance of nanometric, UFG, and micrometric grains which coexist in the same structure, has been shown to increase the bulk yield strength. 121) A synergistic performance to improve electrochemical corrosion resistance and stress corrosion cracking has also been reported in wide-grain size distribution Al-7075 alloy processed by RCS.…”

“…121) A synergistic performance to improve electrochemical corrosion resistance and stress corrosion cracking has also been reported in wide-grain size distribution Al-7075 alloy processed by RCS. 119,121) Other works have focused on the simulation of fracture or residual stress in RCS-processed multimodal materials. 120,[127][128][129]…”

“…2) An example of the above is the rotations (commonly known as tilts) from the ideal texture components in Table 1, which can be widely observed in SPD-processed materials. 119) Tilts originate from non-ideal processing conditions, such as friction between the die and the sample, die geometry, or elasto-plastic characteristics of the material. 26) Moreover, it is difficult to isolate the effect of other microstructural factors, such as grain size, grain shape, storage stress, density of defects, etc.…”