With the trend towards lightweighting, magnesium alloys have become a popular material due to their low density and other advantages. This article details its three major forming technologies: casting (including sand casting, metal mold casting, and pressure die casting), deformation (extrusion, rolling, and forging), and semi-solid injection molding. It analyzes the advantages and disadvantages of each technology and their applications, and also looks forward to future technological upgrades and the widespread adoption of semi-solid technology. 



 

Background
 

In this era of pursuing efficiency and environmental protection, lightweighting has become a key direction for the development of many industries. From automobiles to aerospace, from electronic devices to medical equipment, reducing product weight not only reduces energy consumption and improves performance, but also contributes to sustainable development. In this race for lightweighting, magnesium alloys have become a highly anticipated "star material" due to their unique advantages.

Magnesium alloys, as alloys based on magnesium and composed of other elements, possess numerous advantages such as low density, high specific strength, good shock absorption, and strong electromagnetic shielding capabilities. Their density is approximately 2/3 that of aluminum alloys and 1/4 that of steel, making them highly promising for applications seeking lightweighting. For example, in the automotive industry, using magnesium alloys to manufacture parts can effectively reduce vehicle weight, thereby reducing fuel consumption and emissions. According to relevant research, for every 10% reduction in vehicle weight, fuel efficiency can improve by 6%-8%, which is significant for achieving energy conservation and emission reduction goals.

Magnesium alloys also play an important role in the aerospace field. Because aerospace vehicles are extremely sensitive to weight, every kilogram of weight reduction can bring significant benefits such as fuel savings and increased range. Magnesium alloys' low density and high specific strength make them ideal materials for manufacturing aerospace components, enabling weight reduction while maintaining structural strength.




 

Magnesium alloys are mainly classified into cast magnesium alloys and wrought magnesium alloys based on their forming process. The main forming methods are as follows: Cast magnesium alloys are primarily obtained through casting. This includes sand casting, metal mold casting, and pressure casting (die casting). Among these, die casting is the most mature and widely used technology; currently, over 90% of magnesium alloy products are formed by die casting. Semi-solid injection molding for tuyeres also uses cast magnesium alloys as raw materials.

Wrought magnesium alloys are produced by deformation into plates, bars, tubes, profiles, and forgings of various sizes. High-strength, high-ductility components can be obtained through control of material microstructure and heat treatment processes.
 

The main forming technologies for cast magnesium alloys include the following:
 

1. Sand Casting: A Customized Solution for Large and Complex Parts
Sand casting is a relatively traditional casting method. It uses quartz sand, clay, etc., as molding materials, and forms the mold cavity by manually or mechanically creating the core and assembling the mold. The advantage of this method is that the relatively slow cooling rate of the sand mold (approximately 0.5-2℃/s) facilitates feeding of the casting and effectively avoids defects such as shrinkage cavities and cracks in large parts. Therefore, sand casting is widely used in the aerospace field for manufacturing large structural components, such as helicopter casings and satellite supports.

However, sand casting also has some limitations. Its production cycle is relatively long, typically requiring 3-5 days for single-piece production, and its dimensional accuracy is relatively low, with tolerances ranging from ±1-3mm. This makes sand casting more suitable for the production of small batches of high-value parts.

2. Metal Mold Casting: A Highly Efficient Choice for Mass Production of Small and Medium-Sized Parts. Metal mold casting uses a permanent mold made of steel (i.e., a metal mold). Liquid magnesium alloy is poured directly into the mold, and the mold fills naturally under gravity. Compared to sand casting, metal molds cool much faster (typically 5-15℃/s), refining the grain size and resulting in castings with 15%-20% higher strength than sand-cast parts. Furthermore, metal molds are reusable, with a lifespan exceeding 100,000 cycles, significantly improving production efficiency—5-10 times higher than sand casting.