Magnesium alloys have many distinguished advantages; therefore, they are more and more popularly used in lightweight design of automotive and aviation manufacturing industries. However, its poor plasticity at room temperature has prevented its further application, especially in magnesium alloy sheet forming process. To expand the application of magnesium alloy sheets, single-point incremental forming process for rapid prototype manufacturing and small-scale productions of sheet metal was investigated. By combining finite element numerical simulations with physical experiments, the relationships between the maximum thickness differences and different process parameters are explored, and the optimal process parameters for forming a certain straight wall cylindrical part of AZ31 magnesium alloy were determined. Based on the analysis of the results, the formability of AZ31 magnesium alloy sheet using warm single-point incremental forming (SPIF) is improved with the increases of number of forming stage, forming temperature, and tool diameter but reduced with the increase of feed rate and interlayer spacing. The suitable forming temperature for AZ31 magnesium alloy sheet is about 250°C. For forming the deeper straight wall cylindrical parts, at least four forming stages are needed.

Nano Al films were prepared on AZ31 magnesium alloy samples by DC magnetron sputtering. The effects of sputtering power on the microstructure and corrosion resistance of the Al film were investigated. The results show that the surface of aluminum film is dense and polycrystalline state, and it is oriented along the Al (111) crystal plane. The grain size of Al film first increases and then decreases with the increase of sputtering power. When the sputtering power exceeds 100 W, there is no insignificant effect on the orientation of the Al crystals and the corrosion current density of the samples with Al film are reduced by two orders of magnitude. The corrosion resistance of the magnesium alloy samples with the Al film magnetron sputtered varies with the sputtering power. Compared with low sputtering power, the Al film sputtered by high power has the most excellent corrosion resistance, but too high sputtering power will lead to micro cracks on the Al film, which will adversely affect the corrosion resistance.

Incremental sheet forming (ISF) is a novel flexible forming technology with advantages, such as a low forming force, low-energy-consuming equipment, and good forming performance. The lack of available information about the formability of the two-point incremental forming (TPIF) process makes it limited for practical applications. Taking an irregular stepped part as the target part, the effects of process parameters on the thickness uniformity when using TPIF with a positive die for AA1060 aluminum alloy sheets were investigated. First, the set of optimal parameters regarding the diameter of the tool head, feed rate, and the step size were obtained through orthogonal experiments. Furthermore, the optimal parameter set of the number of forming passes, the direction of movement of the forming tool, and the forming angle was determined and the optimal forming result was numerically and experimentally verified. This demonstrated that the parameters affecting the thickness uniformity of the irregular stepped parts were, in descending order, the diameter of the forming tool, the feed rate, and the step size, with corresponding optimal values of 12 mm, 15,000 mm/min, and 0.4 mm, respectively. With an increase of the number of passes and a decrease of the forming angle between adjacent passes, and adopting an alternating clockwise and counterclockwise toolpath, the thickness uniformity of the formed parts was effectively improved.

In this study, the effect of Ce additions on microstructure evolution of Mg–7Gd–3.5Y–0.3Zn (wt %) alloys during the casting, homogenization, aging and extrusion processing are investigated, and novel mechanical properties are also obtained. The results show that Ce addition promotes the formation of long period stacking ordered (LPSO) phases in the as-cast Mg–Gd–Y–Zn–Ce alloys. A high content of Ce addition would reduce the maximum solubility of Gd and Y in the Mg matrix, which leads to the higher density of Mg12Ce phases in the as-homogenized alloys. The major second phases observed in the as-extruded alloys are micron-sized bulk LPSO phases, nano-sized stripe LPSO phases, and broken Mg12Ce and Mg5RE phases. Recrystallized grain size of the as-extruded 0.2Ce, 0.5Ce and 1.0Ce alloys can be refined to ~4.3 μm, ~1.0 μm and ~8.4 μm, respectively, which is caused by the synthesized effect of both micron phases and nano phases. The strength and ductility of as-extruded samples firstly increase and then decrease with increasing Ce content. As-extruded 0.5Ce alloy exhibits optimal mechanical properties, with ultimate strength of 365 MPa and ductility of ~15% simultaneously.

The forming defects of parts mainly include fracture, springback, thermal expansion, and rough surface during electric hot incremental forming, in which the springback and thermal expansion directly affects the dimensional accuracy of parts. In this paper, the combined optimization of process parameters and unsupported distances was proposed to control the dimensional accuracy of forming parts in the electric hot incremental sheet forming process. The predictive model of major errors was established through the response surface methodology, and then the multi-objective optimal model was obtained using Non-dominated Sorting Genetic Algorithms-II (NSGA-II). Meanwhile, a multi-objective optimal result was determined according to the error compensation feature of the forming process. On this basis, the effect of unsupported distances on dimensional errors was analyzed in detail, and a valid unsupported distance was proposed to further improve the forming accuracy of the whole forming region. Finally, the experimental result demonstrated that the combined optimal method proposed was accurate and feasible.

The effect of titanium on the microstructure, the texture, and the mechanical properties of as-extruded Mg–Sn alloy has been investigated in the present work. The result reveals that the alloy subjected to the optimized extrusion process shows an extremely refined microstructure with an average grain size of 1.7 μm. Meanwhile, the addition of titanium has an obvious effect on intensifying the basal texture where the basal slip cannot be easily activated during tensile testing. As a result, the alloy shows excellent mechanical properties where yield strength and elongation are 200 MPa and 30.2%, respectively. The enhanced yield strength of the alloy can be attributed to the extremely refined microstructure and the intensified basal texture, while the improved elongation of the alloy can be explained by the ultra-fine-grained microstructure through reducing the critical resolved shear stress that favors the prismatic slip activity to accommodate the basal slip.