The main difference between 3003 H18 and 3003 H24 aluminum is their degree of work hardening and the specific manufacturing process used to achieve it. 3003 H18 is fully hardened through cold rolling alone, offering maximum strength and hardness but very low ductility. 3003 H24 is strain-hardened and then partially annealed, providing moderate strength with significantly improved formability, making it much more suitable for bending and structural forming.
When sourcing aluminum for fabrication or manufacturing, the alloy grade is only half the equation. The temper determines how the metal will behave when it interacts with your factory machinery. Selecting H18 when your design requires a 90-degree bend will result in material failure and high scrap rates. Selecting H24 when you need the ultimate rigidity of a flat sheet will compromise your product's structural integrity.
This comprehensive technical guide breaks down the exact differences in mechanical properties, manufacturing processes, and industrial applications between 3003 H18 and 3003 H24 aluminum to help procurement managers and engineers make the right material choice.
What is 3003 aluminum?
Before diving into the specific tempers, it is necessary to establish the baseline properties of the 3003 alloy. 3003 aluminum belongs to the 3xxx series, meaning its primary alloying element is manganese (Al-Mn). The addition of manganese makes it approximately 20% stronger than commercially pure 1100 aluminum.
Crucially, 3003 is a non-heat-treatable alloy. It cannot be strengthened by placing it in a furnace for precipitation hardening. Its strength can only be increased through mechanical cold working at the rolling mill. This reliance on strain hardening is why understanding the specific H-tempers is critical.
3003 H18 Aluminum Plate vs 3003 H24 Aluminum Coil
The "H" designation stands for strain hardening. The digits that follow indicate the exact processing method and the final hardness level.
What is 3003 H18 Aluminum?
The H18 temper indicates a fully hard condition. During manufacturing, the aluminum is continuously cold-rolled to its maximum commercial reduction without any subsequent thermal treatment. The internal grain structure is heavily compressed, resulting in the highest possible strength and hardness for the 3003 alloy. However, this process leaves the metal with very little remaining ductility. It is highly rigid and brittle.
What is 3003 H24 Aluminum?
The H24 temper indicates a half-hard condition, but the "2" is the most important part of the designation. The first digit "2" means the metal was strain-hardened and then partially annealed. At the mill, the aluminum is cold-rolled to a fully hard state (like H18) and then passed through a furnace at a moderate, strictly controlled temperature. This partial annealing process relieves internal stresses and softens the metal back down to a "half-hard" (the digit "4") state. This results in a material with moderate strength but exceptional formability.
| Property | 3003 H24 Aluminum | 3003 H18 Aluminum |
| Strength Level | Medium (Half-Hard) | Higher (Full-Hard) |
| Hardness Level | Medium | High |
| Ductility | Moderate to Good | Low |
| Formability | Good (can be bent) | Poor (brittle) |
| Processing | Suitable for structural forming | Limited to flat or shallow stamping |
| Internal Stress | Relieved | High |
Mechanical Properties Comparison of 3003 H24 and H18 Aluminum Sheet
For engineers programming press brakes and designing stamping dies, precise data is required. The mechanical properties dictate tooling pressure and material limits.
| Mechanical Property | 3003 H24 (Partially Annealed) | 3003 H18 (Fully Hardened) |
| Tensile Strength | 120 – 160 MPa | 140 – 180 MPa |
| Yield Strength | 100 – 140 MPa | 120 – 150 MPa |
| Hardness (Brinell, HB) | ~ 35 – 50 HB | ~ 40 – 55 HB |
| Elongation | Moderate | Low |
Data Analysis for Manufacturing:
Notice the difference in yield strength. 3003 H18 requires significantly more force to permanently deform. However, its low elongation makes it extremely brittle. 3003 H24 has a lower yield strength, meaning it yields to forming tools more easily, and its moderate elongation allows the metal fibers on the outside of a bend to stretch without tearing.
Processing Performance and Industry Case Studies
The difference between a material that has only been cold-rolled (H18) and one that has been partially annealed (H24) becomes glaringly obvious during fabrication.
Processing 3003 H24 Aluminum Coil
Because it has been partially annealed, H24 has relieved internal stress. When bent on a press brake, it behaves predictably. It handles standard bending radii without fracturing and exhibits consistent springback, making it highly favorable for automated CNC operations.
Processing 3003 H18 Aluminum Plate
H18 is full of unreleased internal kinetic energy from the cold rolling process. It is not suitable for forming. If you attempt a 90-degree fold on an H18 sheet, the outer radius will almost certainly crack, or the sheet may snap entirely. It is designed for applications where it remains flat.
The Manufacturing Process Difference
Why go through the trouble of partially annealing (H24) instead of just rolling the metal less to achieve a half-hard state (which would be designated as H14)?
This is a critical metallurgical distinction. While both H14 and H24 are "half-hard," the H24 partial annealing process fundamentally changes the grain structure. Heating the fully hard metal allows the severely deformed grains to recover and relieve internal residual stress without completely losing their strength.
This makes 3003 H24 generally more stable and slightly more ductile during complex forming operations compared to a material that was simply cold-rolled to the same strength level.
The Relationship with Heat Treatment
It must be clearly stated for procurement and engineering teams: neither 3003 H18 nor 3003 H24 can be strengthened by heat treatment.
If you place either of these tempers into a high-temperature furnace, you will not increase their hardness. Instead, the thermal energy will fully anneal the metal, softening it to the "O" temper state and destroying its mechanical strength. The strength of both H18 and H24 comes entirely from mechanical cold working. The heat used in creating H24 is only a partial, highly controlled application designed to soften it slightly, not to harden it.
Applications for 3003 H24 vs 3003 H18 Aluminum Products
Because of their distinct mechanical behaviors, these two tempers are utilized in entirely different manufacturing sectors.
Typical Applications of 3003 H24 Aluminum Coil and Sheet
H24 is selected when the product requires a balance of moderate strength and the ability to be formed, bent, or lightly drawn.
- Architectural Panels: Wall cladding and roofing profiles that require bending and edge hemming.
- Decorative Materials: Trim and enclosures that require structural stability but complex shapes.
- HVAC Components: Ductwork and housings that involve interlocking folds.
- Structural Sheet Metal: Brackets and casings where H18 would crack and O temper would be too weak.
Typical Applications of 3003 H18 Aluminum Plate and Sheet
H18 is selected when the material must remain as rigid as possible, typically in very thin gauges, and involves zero deep forming.
- Bottle Caps and Closures (ROPP): Thin aluminum must resist crushing when applied to beverage and pharmaceutical bottles.
- Roofing Sheets: Flat or gently corrugated sheets relying on maximum hardness for hail and wind resistance.
- Rigid Packaging: Flat packaging components where structural rigidity is paramount.
- High-Hardness Thin Sheets: Any flat application where dent resistance is prioritized over bendability.
Selection Guide for Procurement Managers
When drafting your purchase orders or material specifications, use this logical breakdown to ensure you are buying the correct temper.
Choose 3003 H24 Aluminum if:
- Your manufacturing process involves press brake bending, folding, or moderate stamping.
- You require a material with relieved internal stress to ensure consistent springback.
- You need a structural sheet that offers a balance between physical strength and fabrication flexibility.
Choose 3003 H18 Aluminum if:
- You require the absolute maximum hardness and yield strength available in the 3003 alloy.
- Your product will remain flat or only undergo high-speed, shallow stamping.
- You are utilizing very thin gauges and need to prevent the material from sagging or denting easily.
- You will not subject the material to any sharp bending or deep drawing operations.
Your Certified Supplier for 3003 Aluminum Sheets and Coils
Securing a reliable supply of accurately tempered aluminum is essential for your factory's output. Receiving brittle H18 material when your production line is set up for H24 will lead to catastrophic scrap rates and project delays.
We are a heavy-duty industrial supplier processing high-quality 3003 aluminum products strictly to ASTM B209 and EN 485 international standards. Whether you need the rigid, full-hard characteristics of 3003 H18 aluminum plate or the highly formable, stress-relieved properties of 3003 H24 aluminum coil, we possess the vast inventory and precise manufacturing capabilities to fulfill your exact requirements. We offer extensive custom processing, including precision cut-to-length services, custom width slitting, and mixed-alloy container loading for global export.
Ready to eliminate material inconsistencies and lock in a reliable supply chain? We maintain heavy stock of both 3003 H24 and H18 tempers ready for immediate shipment. Send us your required specifications, thicknesses, and dimensions today. Our export sales engineers will provide a highly competitive, factory-direct quotation along with full Mill Test Certificates (MTC) within hours. Contact us now to secure your aluminum supply.
