Development of a Metal-Based Lightweight Approach Consisting of Cold-Formable Magnesium Sheets in Combination with a Multi-Purpose Powder Coating System

This paper will give an overview about the development of a material system, which consists of a novel formable magnesium alloy that is provided with an effective corrosion protection coating. The corrosion protection is to be realized in the form of a forming stable powder coating, which can be applied in the coil coating process. To improve the tribological properties, additional additives are added to the powder coating. Within this paper, first results concerning tribological and forming behavior of the new lightweight material system are given. For the benchmark, the results are compared with commercially available AZ31 Mg alloy

Microstructure–Mechanical Properties and Application of Magnesium Alloys

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Influence of third alloying element on dislocation slip and twinning activities in Mg-Nd-based alloys

In the present study, the influence of Zn or Al addition as a third alloying element on the deformation mechanisms of Mg–Nd-based alloys was investigated by quasi in situ tensile tests. Distinct mechanical behaviors were observed between Mg–1.0 Zn–1.7 Nd (ZN12, in wt.%) and Mg–1.0 Al–1.7 Nd (AN12) alloys. The ZN12 alloy showed a lower yield strength and higher fracture strain compared to the AN12 sample. A considerable number of slip traces, corresponding to basal and non-basal dislocations, were formed at the early deformation stage of the ZN12 sample. On the contrary, only a few grains in the AN12 sample showed obvious slip traces. To minimize the effect of grain size and texture on the activation of deformation modes, the grains were categorized into several groups based on their grain sizes and Schmid factors. By comparing the grains in the same group, it was found that basal and non-basal slip are preferred in the ZN12 sample compared to the AN12 sample. High activity of tensile twinning was observed in both samples. However, half of the twins were activated after yielding in the ZN12 sample, while a majority of the twins were formed at a higher strain in the AN12 sample.</p

Effect of Process Temperature on the Texture Evolution and Mechanical Properties of Rolled and Extruded AZ31 Flat Products

The application of magnesium flat products is affected by the limited formability at room temperature and the anisotropy of the mechanical properties. The main reason for this is the underlying hexagonal crystal structure of magnesium and the development of strong crystallographic textures during massive forming processes with distinct alignment of basal planes. For an improvement in the properties of semi-finished products, the detailed knowledge of the influence of the manufacturing process on the microstructure and texture evolution of the flat products as a result of dynamic and static recrystallization is required. In this work, flat products made of conventional magnesium alloy AZ31 were manufactured by the rolling process as well as by direct extrusion, with variation in the process temperature. This allowed the development of a distinct variation in microstructures and textures of the flat products. The effects on mechanical properties and formability are highlighted and discussed in relation to the microstructure and texture. It is shown that both the process and the temperature have a major influence on texture and consequently on the material properties

Excellent age hardenability with the controllable microstructure of AXW100 magnesium sheet alloy

Abstract Age-hardenability and corresponding improvement of the mechanical properties of Mg–1Al–0.7Ca and Mg–1Al–0.7Ca–0.7Y alloy sheets are addressed with respect to the microstructure and texture evolution during thermomechanical treatments. A fine grain structure and weak texture with the basal pole split into the sheet transverse direction are retained in the Mg–1Al–0.7Ca–0.7Y sheet even after the homogenization at 500 °C, due to the grain boundary pinning by Y-containing precipitates possessing a high thermal stability. Contrarily, the Mg–1Al–0.7Ca sheet shows a coarse microstructure and basal-type texture after the homogenization. The peak-aged condition is attained after the aging at 250 °C for 1800 s of both homogenized sheets, while the Y-containing sheet shows a higher hardness than the Mg–1Al–0.7Ca sheet. TEM analysis and thermodynamic calculation show the formation of metastable precipitates composed of Al, Ca, Y and Mg in the Mg–1Al–0.7Ca–0.7Y sheet at the homogenized and peak-aged conditions. A significant increase in the yield strength is obtained in the peak-aged condition from 162 MPa after the homogenization to 244 MPa, which arises from the increased size and number density of the precipitates. The high age-hardenability of the Mg–1Al–0.7Ca–0.7Y sheet attributes to the superior mechanical properties with an improved ductility promoted by the weak texture

Modification of Microstructure and Texture in Highly Non-Flammable Mg-Al-Zn-Y-Ca Alloy Sheets by Controlled Thermomechanical Processes

The influence of rolling temperature and pass reduction degree on microstructure and texture evolution was investigated using an AZXW3100 alloy, Mg-3Al-1Zn-0.5Ca-0.5Y, in wt.%. The change in the rolling schedule had a significant influence on the resulting texture and microstructure from the rolling and subsequent annealing. A relatively strong basal-type texture with a basal pole split into the rolling direction was formed by rolling at 450 &#176;C with a decreasing scheme of the pass reduction degrees with a rolling step, while the tilted basal poles in the transverse direction were developed by using an increasing scheme of the pass reduction degrees. Rolling at 500 &#176;C results in a further distinct texture type with a far more largely tilted basal pole into the rolling direction. The directional anisotropy of the mechanical properties in the annealed sheets was caused by the texture and microstructural features, which were in turn influenced by the rolling condition. The Erichsen index of the sheets varied in accordance to the texture sharpness, i.e., the weaker the texture the higher the formability. The sheet with a tetrarchy distribution of the basal poles into the transverse and rolling directions shows an excellent formability with an average Erichsen index of 8.1

Analysis of the dislocation activity of Mg–Zn–Y alloy using synchrotron radiation under tensile loading

An understanding of deformation behavior and texture development is crucial for the formability improvement of Mg alloys. X-ray line profile analysis using the convolutional multiple whole profile (CMWP) fitting method allows the experimental determination of dislocation densities separately for different Burgers vectors up to a high deformation degree. A wider use of this technique still requires exploration and testing of various materials. In this regard, the reliability of the CMWP fitting method for Mg–Zn–Y alloys, in terms of the dislocation activity during tensile deformation, was verified in the present study by the combined analysis of electron backscatter diffraction (EBSD) investigation and visco-plastic self-consistent (VPSC) simulation. The predominant activity of non-basal 〈a〉 dislocation slip was revealed by CMWP analysis, and Schmid factor analysis from the EBSD results supported the higher potential of non-basal dislocation slip in comparison with basal 〈a〉 dislocation slip. Moreover, the relative slip activities obtained by the VPSC simulation also show a similar trend to those obtained from the CMWP evaluation