Extrusion Of Mg Alloy Research Articles

Formation mechanism and evolution of surface coarse grains on a ZK60 Mg profile extruded by a porthole die

Porthole die extrusion of Mg alloys was studied by means of experimental and numerical studies. Results indicated that an inhomogeneous microstructure formed on the cross-section of the extruded profile. On the profile surface, abnormal coarse grains with an orientation of <11−20> in parallel to ED (extrusion direction) appeared. In the profile center, the welding zone was composed of fine grains with an average size of 4.19 μm and an orientation of <10−10> in parallel to ED, while the matrix zone exhibited a bimodal grain structure. Disk-like, near-spherical and rod-like precipitates were observed, and the number density of those features was lower on the profile surface than that in the profile center. Then, the formation and evolution of coarse grains on the profile surface were investigated, which were found to depend on the competition between static recrystallization and grain growth. The stored deformation energy was the factor dominating the surface structure through effective regulation over nucleation of the precipitates and recrystallization. A profile with a low stored deformation energy suppressed formation of precipitates and consequently facilitated grain growth rather than recrystallization, resulting in the formation of abnormal coarse grains. Finally, the surface coarse grains contributed detrimentally to hardness, tensile properties, and wear performance of the bulk structure.

Recent Progress and Development in Extrusion of Rare Earth Free Mg Alloys: A Review

Mg and its alloys are the lightest structural metals available and are extremely attractive for applications as lightweight components, particularly in the automobile, electronic, and aerospace industries. The global market for wrought Mg alloys has steadily expanded over the past decade. And numerous studies have been carried out to meet this increasing demand of high-performance Mg alloys. However, Mg extrusion alloys have had a very limited usage so far. To overcome existing industrial challenges, one desirable approach is the development of low-cost rare earth (RE) free Mg extrusion alloys with superior mechanical properties. This review will introduce the recent research highlights in the extrusion of Mg alloys, specifically focusing on low-cost RE-free Mg alloy. The results from both the literature and our previous study are summarized and critically reviewed. Several aspects of RE-free Mg extrusion alloys are described in detail: (1) novel alloying designs including Mg–Al-, Mg–Zn-, Mg–Ca-, Mg–Sn-, and Mg–Bi-based alloys, (2) advanced extrusion techniques, and (3) extrusion-related severe plastic deformation (SPD) processing. Accordingly, considering the large gap in mechanical properties between the current RE-free Mg alloys and high-performance aluminum alloys, new alloy design, processing route control, and recommendations for future research on RE-free Mg extrusion alloys are also proposed. We hope this review will not only offer insightful information regarding the extrusion of RE-free Mg alloys but also inspire the development of new Mg extrusion technologies.

Physical and numerical modelling of backward extrusion of Mg alloy with Al coating

Although Mg alloys possess many attractive properties, their use has been limited due to their poor corrosion resistance. Therefore, in the present paper a process for Al coating on Mg alloys by hot extrusion was investigated. Physical simulations confirmed capabilities of this process and Al coating on a Mg alloy was obtained. Prediction of microstructure evolution and determination of optimal process parameters were the objectives of the present numerical simulations. Cellular automata were used to reach the former goal, while for the latter goal optimization analysis was applied to find the best technological parameters.

Review on Hydrostatic Extrusion of Magnesium Alloys

Magnesium wrought alloys are of special interest for structural components owing to their improved microstructures and mechanical properties by comparison with Mg cast parts. However, the market of Mg wrought alloys is still relatively small and one of the most important limitations for their application in areas such as aviation and spaceflight is that their strength is still not high enough to be widely used. Currently, more and more attention are paid to hydrostatic extrusion of Mg alloys because the extruded Mg alloys which exhibit extremely fine grains and high strength can be easily obtained by hydrostatic extrusion process. This review detailed the microstructures and mechanical properties of various wrought Mg alloys subjected to hydrostatic extrusion. Furthermore, numerical simulations and processing parameters optimization of the hydrostatic extrusion were also discussed. Finally, the current problems and development trends of hydrostatic extrusion of high-strength Mg alloys were also put forward.