Papers by Keyword: Wrought Magnesium Alloys

Abstract: Currently magnesium alloys are used for different applications in the transportation industry where cast magnesium alloys dominate the market. Although cast alloys predominate over wrought products such as extrusions, forgings, sheet and plate, the latter are also being used in a variety of different applications. Recently, a growing interest in the automotive industry in looking at potential applications for magnesium turned back towards wrought alloys. Typically, applications of magnesium sheets are sought in automotive or aeronautics industry. However, the spectrum of potential applications can be significantly expanded. For example, body protection systems for civil services like police, custom officers and prison personnel currently include anatomically shaped aluminium alloy sheets. Replacement of aluminium alloys by magnesium to result in substantial weight savings up to 30%.

Abstract: In this work, four Mg-Zn-Ce sheets were processed on an industrial scale by “Helholtz-ZentrumGreesthacht” company. To study the effect of alloying elements and annealing conditions on the rolled sheets, these sheets were annealed at different conditions. Mechanical properties of these rolled and annealed sheets were determined in rolling and transverse directions. Optical microscopy was used to investigate microstructure evolution and stability as well as grain size after annealing. Annealing at 450°C, 1 hr for A and D sheets provides microstructure stability of these sheets. Whereas, annealing B and C sheets for one hour at 400 and 350°C, respectively, provide the optimum annealing conditions. In the studied alloys, the highest zinc (Zn) presence alloyed with magnesium significantly increases the grain size and the amount of precipitates. Whereas, the highest cerium (Ce) presence alloyed with magnesium, refines the grain size during the recrystallization process.

Abstract: In recent several years, although production of magnesium has risen dramatically, production of magnesium alloy sheet remains still at a very low level in practical use. The major barrier to greatly increased magnesium alloy use has been in still primarily high manufacturing cost as well as poor work ability of wrought magnesium sheet alloys. One of the author has investigated in cold roll forming of magnesium alloy, however detailed forming characteristics of the wrought magnesium alloy sheets has not been clarified. The aim of the study is to confirm possibilities of practical use of wrought magnesium alloy by using told roll forming process. A three dimensional elasto-plastic analysis by finite element method (FEM) has been conducted to examine the shapes of cross section, spring back characteristics, bending strains and longitudinal membrane strain of magnesium alloy sheet and cold rolled steel sheet during forming.

Abstract: Microstructures and phase compositions of as-cast and extruded ZK60-xHo (x=0~5) alloys were analyzed by X-ray diffraction, differential scanning calorimetry, optical microscope, scanning electron microscope and transmission electron microscope. Meanwhile, tensile mechanical property and impact toughness were tested. The results showed that as-cast microstructure was refined gradually with increasing the Ho content. Mg-Zn-Ho new phase increased gradually, while MgZn₂ phase reduced gradually to disappear. Second phase tended to distribute along grain boundary by continuous network. As-cast tensile mechanical property remained almost unchanged and impact toughness value α_nK was low (9~17 J/cm²). After extrusion by λ=40/T=593 K, grain size reached the micron level (1~5 μm) and broken second phase distributed dispersedly. Extruded tensile mechanical property was enhanced obviously. Tensile strength σ_b at ambient temperature increased gradually from 355 MPa for ZK60 alloy to 375 MPa for ZK60-4.77Ho alloy, while elongation δ decreased gradually from 19.5% to 12.5%. σ_b at 473 K increased gradually from 120 MPa to 169 MPa. Meanwhile, α_nK was enhanced to 26~54 J/cm². Fine grain and few fine dispersed second phase enhanced the tensile mechanical property and impacted toughness of magnesium alloys effectively.

Abstract: In this work, the superplastic behavior of AZ31, AZ61 and AZ80 magnesium alloys was investigated. The alloys were hydrostatically extruded at only 150 °C to get fine grained microstructures (−2, 10⁻³ and 10⁻⁴ s⁻¹. It was found that all alloys exhibited superplasticity at 200 °C, 175 °C and 225 °C for AZ31, AZ61 and AZ80 alloys, respectively. Low temperature dynamic recrystallisation played an important role for generating a finer and homogeneous microstructure during testing which enhances the deformation behavior of the alloys at these temperatures.