The strength of extruded aluminum is usually higher than that of cast aluminum, but the specific degree of robustness needs to be combined with the alloy composition, heat treatment process and product application scenarios. The following three dimensions are analyzed from material properties, processing technology and application scenarios:
Material Properties: Strength Advantages of Extruded Aluminum
1. Tensile Strength and Yield Strength
Extruded aluminum profiles are formed through the hot extrusion process, and their tensile and yield strengths are significantly higher than those of cast aluminum. For example:
- industrial pure aluminum extrusion tensile strength can be increased from 65MPa to 185MPa (6 passes extrusion), yield strength from 52MPa to 124MPa, the enhancement rate of 185% and 138%.
- 6061 aluminum alloy extrusion state tensile strength of 198.8MPa, after heat treatment up to 323.6MPa, yield strength from 144.3MPa to 234.6MPa.
- Casting aluminum alloy tensile strength is usually around 200MPa, even through the solid solution treatment (T6), the strength is not more than 300MPa (due to internal porosity problems, die-casting products generally do not do heat treatment).
2. Hardness and Wear Resistance
（1）The hardness of extruded aluminum profiles can be further enhanced by heat treatment. For example, the hardness of 6061 aluminum alloy increases significantly after extrusion, while the hardness of cast aluminum alloy is usually less than 100HBW.
（2）The surface of extruded aluminum profiles can be anodized to form an oxide film with a thickness of 0.12mm, which enhances abrasion and corrosion resistance; the surface treatment process of casting aluminum alloys is relatively complex, and the abrasion resistance is poor.
3. Elongation and toughness
The elongation of extruded aluminum profiles decreases as the number of extrusion passes increases (e.g., from 28.8% to 8.8% after one pass), but still retains a certain degree of toughness; casting aluminum alloys with lower elongation (about 70% less than sand casting) and poorer toughness.
Processing: Structural Advantages of Extruded Aluminum
1. Metal flow uniformity
Extruded aluminum extrusion can achieve uniform metal flow through mold design, the surface layer and the center of the organization performance is consistent; casting aluminum alloy due to uneven metal flow, easy to produce shrinkage, cracks and other defects, resulting in a decline in mechanical properties.
2. Tooling Costs and Productivity
Extruded aluminum tooling is low-cost and suitable for small-lot production; cast aluminum tooling is expensive and requires large-scale production to spread the cost, but is highly productive and can make complex-shaped parts.
3. Heat treatment process
Extruded aluminum profiles can be significantly strengthened by solution treatment + aging strengthening (e.g., T6 condition); cast aluminum alloys have limited heat treatment effect due to internal porosity problems, and the strength enhancement is smaller.
Application Scenarios: Selection of Processes Based on Requirements
1. Extruded Aluminum Profiles Applicable Scenarios
High Strength Demand: such as building structural parts (broken bridge aluminum doors and windows), electronic radiators, curtain wall frames, etc., which need to withstand large loads and require high dimensional accuracy.
Lightweight demand: extruded aluminum alloy profiles are lightweight (density of about 2.7g/cm³), with 1/3 of the strength of steel but lighter in weight, suitable for aerospace, automotive and other fields.
Complex cross-section design: any cross-section shape can be extruded (e.g. pen tubes, rechargeable treasure shells), reducing the need for machining.
2. Casting Aluminum Alloy Applicable Scenario
Complex shape parts: such as toys, connectors, decorative heads, etc., can be cast with thin-walled, porous structure and high surface finish (up to grade 5-8).
Mass production: die-casting process is suitable for mass production, good dimensional stability (accuracy of 6-7 grade), interchangeability.
Cost-sensitive applications: although the mold cost is high, but the cost of a single piece with the increase in production and reduce, suitable for consumer electronics, automotive parts and other fields.
Comprehensive Comparison and Conclusion
1. Extruded aluminum profiles are preferred when high strength, high precision, light weight and complex cross-section designs are required (e.g., architectural structures, electronic heat dissipation).
2. For complex shapes, thin-walled parts and mass production efficiency, cast aluminum alloys are more advantageous (e.g., toys, automotive parts).
3. The actual choice needs to be evaluated in combination with the alloy composition (e.g. 6061, 7075 aluminum alloy is stronger), heat treatment process and product application scenarios.
