Cast Aluminium Alloy

Cast aluminium alloy refers to aluminium alloy materials used to produce components of desired shapes directly by pouring molten metal into moulds (the casting process). In short, components are formed directly before undergoing post-processing, fundamentally differing in both form and manufacturing process from wrought aluminium alloys, which are first rolled into sheets or extruded into profiles before being shaped.

🔬 Core Characteristics

The primary advantage of cast aluminium alloy lies in its exceptional castability, enabling the production of intricate components while delivering low density, high specific strength, and superior corrosion resistance. Key technical parameters include excellent fluidity, minimal shrinkage tendency, and low gas absorption to ensure high-precision forming.

Based on the primary alloying elements, cast aluminium alloys are categorised into four major series:

• Aluminium-Silicon series: The most common and widely utilised (accounting for over 50% of all cast aluminium alloys [1][8]), offering the best castability.

• Aluminium-Copper series: High strength and excellent thermal resistance, though with slightly lower castability and corrosion resistance.

• Aluminium-Magnesium series: Lowest density and superior corrosion resistance, combined with relatively high strength.

• Aluminium-Zinc series: Characterised by its "self-quenching" property, allowing it to be used without heat treatment.

🚗 Automotive Applications

Cast aluminium alloy serves as the cornerstone of automotive lightweighting. According to 2021 industry data, cast aluminium alloys accounted for approximately 75% of all aluminium consumed globally in the automotive sector. Applications span numerous critical components from powertrains to body structures:

• Engine systems: Cylinder heads, engine blocks, pistons, etc. The lightweight properties and high thermal conductivity of aluminium alloys offer distinct advantages here.

• Drivetrain and chassis systems: Gearbox casings, alloy wheels, brake callipers, steering knuckles, and more. For instance, aluminium alloy wheels can reduce weight by 2 to 3 kg per wheel compared to conventional steel wheels.

• Body structural components: Subframes, crossmembers, etc. With the rapid evolution of integrated die-casting technology, its scope of application is expanding swiftly.

⚙️ Industry Landscape and Technological Trends

Currently, cast aluminium alloy technology is undergoing significant evolution, largely driven by the lightweighting demands of new energy vehicles.

• Mainstream alloy grades: ADC12 (originating from Japanese standards) remains the most prevalent and widely used grade across the industry, extensively utilised in the manufacturing of engine blocks, cylinder heads, shock absorbers, and other components. In addition, A380 and A356 are also heavily utilised alloys.

• Heat-treatment-free materials and integrated die-casting: This represents the most crucial technological frontier today. Traditional die-cast parts require heat treatment for structural reinforcement, but large integrated castings are susceptible to thermal deformation during heat treatment. Heat-treatment-free cast aluminium alloys (such as the China-developed WZL series) can be utilised directly in their as-cast condition, removing key barriers for integrated die-casting technology. This breakthrough enables complex assemblies previously made of over 70 individual components to be consolidated into a single casting, dramatically streamlining the manufacturing process.

• High-performance material R&D: Domestic players such as Weiqiao Group have developed the next-generation WZL-series cast aluminium alloy. Through composition optimisation and grain refinement techniques, it delivers performance over 20% higher than conventional counterpart alloys, and has already been adopted in vehicle chassis and body frames.