Automotive aluminum wheel hub casting chemical element
| Element | Composition (%) | ||||||
| A356 | A356.2 | 356. 0 | 356. 1 | 356. 2 | ZL 101 | ZL 101 A | |
| Aluminum (Al) | Remainder | Remainder | Remainder | Remainder | Remainder | Remainder | Remainder |
| Silicon (Si) | 6.5-7.0 | 6.5-7.0 | 6.5-7.5 | 6.5-7.5 | 6.5-7.5 | 6.5-7.5 | 6.5-7.5 |
| Magnesium (Mg) | 0.25-0.45 | 0.30-0.45 | 0.20-0.45 | 0.25-0.45 | 0.30-0.45 | 0.25-0.45 | 0.25-0.45 |
| Iron (Fe) | 0.0-0.2 | 0.0-0.12 | 0.0-0.6 | 0.0-0.5 | 0.0-0.13 | 0.0-0.5 | 0.0-0.2 |
| Copper (Cu) | 0.0-0.2 | 0.0-0.1 | 0.0-0.25 | 0.0-0.25 | 0.0-0.1 | 0.0-0.2 | 0.0-0.1 |
| Zinc (Zn) | 0.0-0.1 | 0.0-0.05 | 0.0-0.35 | 0.0-0.35 | 0.0-0.05 | 0.0-0.3 | 0.0-0.1 |
| Manganese (Mn) | 0.0-0.1 | 0.0-0.05 | 0.0-0.35 | 0.0-0.35 | 0.0-0.05 | 0.0-0.35 | 0.0-0.1 |
| Titanium (Ti) | 0.0-0.2 | 0.0-0.2 | 0.0-0.25 | 0.0-0.25 | 0.0-0.2 | 0.0-0.25 | 0.0-0.2 |
| Remainder (each) | 0.0-0.05 | 0.0-0.05 | 0.0-0.05 | 0.0-0.05 | 0.0-0.05 | - | - |
| Remainder (total) | 0.0-0.15 | 0.0-0.15 | 0.0-0.15 | 0.0-0.15 | 0.0-0.15 | 0.0-1.1 | 0.0-0.7 |
The impact of chemical composition on automotive aluminum wheel hub castings
With the increase of Mg content, the tensile strength, yield strength, and hardness of the alloy all increase, but the elongation after fracture decreases.
When the Fe content increases, the strength of the alloy, especially the elongation after fracture, significantly decreases, leading to the brittleness of the casting. Therefore, the addition of Cr is mainly used to eliminate the harmful effects of Fe.
The presence of Cu and Zn reduces the elongation after fracture and corrosion resistance of A356 alloy. Therefore, it is advisable to avoid mixing Cu and Zn elements.
Rare earth elements have significant chemical activity and strong affinity for impurities such as sulfur, oxygen, hydrogen, and nitrogen. Adding rare earth elements can help eliminate the adverse effects of these impurities in Al-Si alloys.
The mechanical properties of automotive aluminum wheel hub casting
| Alloy | Mechanical properties | ||
| Tensile strength / MPa | Yield stress / MPa | Elongation（%） | |
| 356 | 265 | 186 | 5 |
| A356 | 284 | 206 | 10 |
| A356.2 | 290 | 210 | 12 |
| ZL 101 A | 287 | 210 | 12 |
Quality standards for automotive aluminum wheel hub casting
Surface quality
The castings will be trimmed to remove flash and burrs, ensuring a smooth surface. Non-machined surfaces will be free from any marks or residual aluminum. After polishing, the castings will be dimensionally compliant with the casting drawings.
However, for areas where polishing is not possible or where there are specific surface quality requirements, customers should clearly specify in the drawings, technical agreements, or contracts in advance.
Additionally, the roughness of non-machined surfaces of the castings will not exceed 12.5μm. This means that the non-machined surfaces of the castings will maintain a good level of smoothness, which contributes to meeting the appearance and performance requirements of the customers.
Internal quality
The castings are free from cold shuts and cracks defects.
The castings will undergo X-ray non-destructive testing according to the inspection methods specified in the table. The acceptance level for defects will not exceed the level specified in the table below.
| Defect Names | Wheel Disc | Wheel Spoke | Wheel Rim |
| Gas Pores | 4 | 4 | 3 |
| Inclusions (Low Density) | 4 | 5 | 4 |
| Inclusions (High Density) | 4 | 5 | 4 |
| Pinholes (Circular) | 4 | 3 | 4 |
| Pinholes (Elliptical/Oval) | 3 | 3 | 4 |
| Shrinkage Cavity | 3 | 3 | 2 |
| Porosity | 3 | 4 | 3 |
Heat treatment process for automotive aluminum wheel hub casting
Solution treatment
The aluminum alloy wheel is heated to a temperature of (535±5)°C and held at this temperature for 3 to 4 hours for solution treatment (excluding the time required for heating to the temperature).
Quenching
After solution treatment, the aluminum alloy wheel is rapidly cooled using water as the quenching medium. The quenching temperature ranges from 60°C to 100°C, and the quenching duration (transition time) should be less than 15 seconds.
Aging treatment
After quenching, the aluminum alloy wheel is reheated to a temperature of (155±5)°C and held at this temperature for 3 to 4 hours for aging treatment.
Attention
Specific heat treatment processes may be adjusted accordingly based on the size, dimensions, and specific requirements of the customer's parts.
This is to ensure that the final aluminum alloy wheels meet the required mechanical properties and quality standards. Therefore, in practical operations, we will optimize and adjust the processes based on the specific circumstances.
Why choose Chalco Aluminum
Global collaboration and recognition
Chalco is a supplier to numerous automotive companies, including Chinese brands such as BYD, Geely, Chery, Great Wall, Changan, and Dongfeng; German brands such as Mercedes-Benz, BMW, Volkswagen, and Audi; French brand Renault; American brands Tesla, General Motors, Ford, and Chrysler; and Japanese brands Honda and Toyota.
Through a series of international standards and certifications, including ISO/TS16949, ISO14001, ISO-9001, IATF 16949, VDA 6.1, JIS D 5301, Chalco has gained recognition and honors from numerous international companies.
Design and prototyping
Chalco offers drawing creation, professional design, and provides prototyping with feedback and modifications to ensure precise dimensions of castings.
We adhere to strict quality control, meticulously managing temperature and pressure to guarantee the strength and precision of the castings.
Process and automation
Chalco utilizes gravity casting, low-pressure casting, and spin forming processes, combined with automated pouring, casting, and spin forming equipment using robotic arms, to achieve higher efficiency and precision in the production process.
High-quality casting molds and specialized coatings are employed to ensure production quality.
Quality assurance
Chalco conducts comprehensive and precise testing throughout the entire process, including dimensional inspection, air tightness testing, wheel dynamic imbalance testing, and more, to ensure product quality.
