The present overview gives a new approach toward developments and recent achievements in severe plastic deformation. The review focuses on several subjects. First, an outline of SPD research status in the world is presented by literature analysis based on the total number of publications, citations, and the contribution of the top-ranked countries. Second, the mechanisms of grain refinement and grain growth during SPD processing are discussed by means of the latest concepts. Third, all SPD methods invented so far are classified based on a new approach. Up to now, the growing tendency of researchers to introduce new SPD techniques results in a large number of SPD methods which can be considered as new or modified techniques or a combination of previous ones. Such a reference can help to prevent the future duplication to introduce the SPD processes, which are technically similar. At the end, the practical applications of ultrafine/nanostructured materials and industrial commercialization of SPD methods are summarized.

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An overview on severe plastic deformation: research status, techniques classification, microstructure evolution, and applications

The effect of grain size and grain boundary misorientation on the corrosion resistance of commercially pure aluminium

A study on corrosion behavior of friction stir welded and tungsten inert gas welded AA2014 aluminium alloy

Corrosion behavior and mechanical properties of Al-Zn-Mg aluminum alloy weld

Pitting corrosion of naturally aged AA 7075 aluminum alloys with bimodal grain size

Corrosion behaviour and mechanism of new aerospace Al–Zn–Mg alloy friction stir welded joints and the effects of secondary Al3ScxZr1−x nanoparticles

Superplastic property and microstructure evolution during the deformation of an Al-6.10Mg-0.25Sc-0.1Zr alloy with fine grains, produced by a new asymmetrical rolling technology, were investigated by tensile tests and microscopy methods. The results show that new asymmetrical rolling can considerably enhance the high strain rate superplasticity. A maximum ductility of 3200% can be achieved at 500 °C and 5×10 −2  s −1 . Under the same cold rolling reduction (75%), although the maximum elongation is comparable to that of the traditionally rolled same materials, asymmetrical rolling can increase the optimum strain rate up to 10 times. The microstructure results show that, during superplastic deformation, low angle grain boundaries gradually transfer into high angle grain boundaries and the grains gradually orientate randomly. The excellent high stain rate superplasticity can be ascribe to the refined grains and the presence of nano-scaled Al 3 (Sc, Zr) particles which can stabilize the fine-grains during hot deformation. The grain boundary sliding is the predominant superplastic deformation mechanism in the studied alloy.

Achieving high strain rate superplasticity of an Al-Mg-Sc-Zr alloy by a new asymmetrical rolling technology

A new fine-grained Al–Mg–Sc–Zr alloy sheet with the grain size of 2.5 μm was prepared by simple rolling and thermal treatment process. Superplastic investigations in the temperature range of 450–550 °C and initial strain rate range of 1×10−3 s−1–1×10−1 s−1 show that a maximum elongation of 3250% is achieved at 525 °C and 5×10−3 s−1. The alloy also exhibits excellent superplastic ductility (>2390%) in the temperature interval 475–500 °C at 5×10−2 s−1. Analyses on the superplastic data reveal that the average values of the strain rate sensitivity and activation energy of the Al–Mg–Sc–Zr alloy are about 0.45 and 83 KJ/mol, respectively. The microstructure results show that the studied alloy is characterized by a high fraction of low angle grain boundaries and strong Copper, Brass and Cube texture. During superplastic deformation, low angle grain boundaries gradually transfer into high angle grain boundaries and the grains gradually orientate randomly. The fine coherent Al3(Sc, Zr) particles play an important role in obtaining excellent superplasticity. Grain boundary sliding is the predominant deformation mechanism.

Achieving high superplasticity of a new Al–Mg–Sc–Zr alloy sheet prepared by a simple thermal–mechanical process

A new Al-Mg-0.15% Sc-0.10% Zr (wt%) alloy sheet with an average (sub)grain size of ~2.25 µm was processed by a simple thermomechanical processing. Excellent superplastic (elongations of ≥800%) can be achieved at a temperature range of 450–500 °C and a high strain rate range of 1×10−2–1×10−1 s−1. A maximum elongation of ~1579% was obtained at 475 °C and a high strain rate of 5×10−2 s−1. Electron back scatter diffraction analysis and transmission electron microscopy results showed that superior superplastic ductility of the Al-Mg-Sc-Zr alloy can be ascribed to the complete transformation of low angle grain boundaries to high angle grain boundaries due to the occurrence of continuous dynamic recrystallization and the presence of stable coherent Al3ScxZr1−x particles that effectively impede the growth of the grains during superplastic deformation. Besides, strong β-fiber rolling textures gradually weakened, and random textures were predominant in the superplastic deformed alloy. Analyses on the superplastic data revealed that the average strain rate sensitivity parameter and the average activation energy of the Al-Mg-Sc-Zr alloy were ~0.48 and ~84.4 kJ/mol–1, respectively. All results indicated that the main superplastic deformation mechanism was grain boundary sliding.

Superplastic behavior and microstructure evolution of a new Al-Mg-Sc-Zr alloy subjected to a simple thermomechanical processing

7020 aluminum alloy plates were welded by metal inert gas welding method, with the ER5183 welding wire containing Zr and ER5356 welding wire without Zr, respectively. The mechanical properties, corrosion behavior, and microstructures of these two welded joints were investigated. The tensile strength and ductilities of the joints are inferior to those of base alloy, and the lowest hardness is obtained in the welded zone, while the heat-affected zones are more sensitive to corrosion than the base metal and welded zones. The base metal shows a deformed subgrains microstructure, and the heat-affected zones still remain in elongated shape, where the soften zones form as a result of η′ (MgZn2) coarsening. Two welded zones are mainly characterized by as-cast structure; however, grains are refined and a zone of equiaxed grains forms along the bonding boundary due to the Zr addition into ER5183 Al alloy. Accordingly, the mechanical properties and corrosion resistance in this zone of the joint with ER5183 exhibit better than those of the joint with ER5356.

Xiaowu Cao

Papers

Corrosion behaviour and mechanism of new aerospace Al–Zn–Mg alloy friction stir welded joints and the effects of secondary Al3ScxZr1−x nanoparticles

Achieving high strain rate superplasticity of an Al-Mg-Sc-Zr alloy by a new asymmetrical rolling technology

Achieving high superplasticity of a new Al–Mg–Sc–Zr alloy sheet prepared by a simple thermal–mechanical process

Superplastic behavior and microstructure evolution of a new Al-Mg-Sc-Zr alloy subjected to a simple thermomechanical processing

Mechanical Properties, Corrosion Behavior, and Microstructures of a MIG-Welded 7020 Al Alloy