3003 H18 aluminum sheet is fully hard with maximum strength and minimal ductility, making it ideal for flat, load-bearing structural panels. In contrast, 3003 H16 aluminum sheet is strain-hardened to a lesser degree (3/4 hard). It offers slightly lower strength but retains a better balance of flexibility, allowing for moderate forming without severe cracking.
Basics of the 3003 Aluminum Alloy
The 3003 aluminum series is an Aluminum-Manganese (Al-Mn) alloy. It contains about 1.2% manganese, which makes it about 20% stronger than pure 1100 series aluminum. It is a non-heat-treatable alloy. This means you cannot put it in an oven to harden it. Instead, its strength comes purely from cold working (rolling it under heavy pressure at room temperature). 3003 is widely known in the industry for its excellent corrosion resistance and moderate price.
What Is H18 Temper in 3003 Aluminum Sheet?
The "H18" temper means the metal is Full Hard.
During production, the aluminum is cold-rolled to its absolute maximum hardness. Because of this extreme pressure, the metal's internal structure becomes highly rigid. It offers the highest possible strength in the 3003 series, but it loses almost all its ability to stretch. Its ductility is the lowest.
What Is H16 Temper in 3003 Aluminum Plate?
The "H16" temper means the metal is 3/4 Hard.
The factory stops the cold-rolling process just before reaching full hardness. Because it is not compressed to its maximum limit, H16 retains a small amount of elasticity. It is still a very stiff and strong material, but it forgives minor bending and light forming much better than H18.
| Property | 3003 H18 | 3003 H16 |
| Strength | Maximum | High |
| Ductility (Stretch) | Very low | Moderate |
| Formability | Poor | Limited but workable |
| Hardness | Highest | Slightly lower |
| Best Used For | Flat roofing, structural panels | Appliance panels, light forming |
Mechanical Properties of 3003 Aluminum Coil
The actual test data tells the whole story. Based on ASTM B209 specifications, here is how the mechanical properties stack up.
| Property | 3003 H18 | 3003 H16 |
| Tensile Strength | ≥ 200 MPa | 170 – 210 MPa |
| Yield Strength | ≥ 170 MPa | 140 – 180 MPa |
| Elongation | ≥ 2% | 3% – 5% |
Data Conclusion:
While H18 is definitively the strongest (guaranteed minimum 200 MPa tensile), H16 is not weak. H16 still offers up to 210 MPa. The real difference is in the elongation. H18 only stretches 2% before tearing, whereas H16 can stretch up to 5%. This 3% difference changes everything on the factory floor.
| Fabrication Process | 3003 H18 | 3003 H16 |
| Bending | Very poor (Cracks easily) | Limited (Needs a proper radius) |
| Deep Drawing | Not suitable | Possible (For shallow forms only) |
| Welding | Good | Good |
| Machining | Moderate (Chips cleanly) | Moderate |
The Bending Difference:
Do not put a 3003 H18 aluminum sheet into a press brake for a tight 90-degree fold. The outer edge of the bend will snap. H16, being 3/4 hard, can survive a gentle bend, but it still requires a generous inner bending radius. Neither of these tempers is as easy to fold as H14 (Half Hard).
Typical Applications for 3003 H18 Aluminum
H18 is chosen when the metal must carry a load, resist impacts, and remain perfectly flat.
- Roofing Sheets: Prevents denting from hail and heavy rain.
- Industrial Wall Cladding: Withstands wind pressure on factory exteriors.
- Structural Panels: Used in trailer sides where stiffness is mandatory.
- Insulation Covering: Hard protective jacketing for oil and gas pipes.
Typical Applications for 3003 H16 Aluminum
H16 is chosen when you need a rigid panel that also requires minor shaping or curved edges.
Appliance Panels: Back panels for refrigerators or washing machines that need slight edge folding for screws.
Light Forming Parts: Shallow trays or protective covers.
Decorative Panels: Architectural parts that require a gentle curve rather than a sharp angle.
Automotive Sheet Components: Underbody heat shields requiring minor stamping.
Application Selection Table of 3003 H18 vs H16 Aluminum Sheet
| Application | Recommended Temper |
| Structural panels | H18 |
| Corrugated roofing | H18 |
| Light bending / shallow folds | H16 |
| Home appliance panels | H16 |
| Decorative forming | H16 |
Processing Risks in the Workshop
When comparing 3003 H18 vs H16, you must consider the manufacturing risks. Choosing the wrong temper leads to wasted material.
| Risk Factor | 3003 H18 | 3003 H16 |
| Cracking during bending | High | Medium |
| Deformation control | Easy (Stays flat naturally) | Moderate |
| Processing flexibility | Low | Better |
If your product requires bending, guessing between H18 and H16 can lead to a high scrap rate. We offer a Free Technical Review. Send us your drawing and bend radius. Our engineers will evaluate it and tell you exactly which temper you need to ensure a zero-crack production run.
Contact Our Technical Team Here
Cost and Machining Expense Comparison
- Material Cost: The raw price per ton for H18 and H16 is almost identical. H18 might cost slightly more due to the extra electricity and time required to roll it to full hardness.
- Processing Cost: If your design requires forming, H18 will increase your costs massively because of cracked, scrapped parts. H16 is safer for forming.
- Overall Cost Efficiency: H18 is the most cost-effective if you just need raw, flat strength. H16 is more economical if your production line requires any shaping.
- Choose Maximum Strength: If the sheet stays completely flat and needs to resist impacts (like a roof), buy H18.
- Choose Moderate Forming: If the sheet needs to be bent slightly at the edges to fit into a frame, buy H16.
- Choose Structural Use: For load-bearing flat surfaces, buy H18.
- Choose Balanced Performance: If you are not entirely sure how the end-user will install the panel, H16 offers a safer, more forgiving middle ground.
Limitations of Each Temper
Limitations of 3003 H18:
- It is almost impossible to bend sharply.
- It is highly prone to stress cracking if forced into a new shape.
- It cannot handle deep drawing processes.
Limitations of 3003 H16:
- Its yield strength is lower than H18, meaning it will permanently dent slightly earlier than H18 under a heavy direct impact.
- It is not suitable for heavy-duty structural frames where maximum rigidity is the only priority.
Choose the Right Aluminum Temper Today
Using the correct temper is the easiest way to lower your manufacturing costs and improve product quality. As a direct manufacturer, we supply both ASTM B209 compliant 3003 H18 and H16 aluminum sheets and coils. We offer exact custom sizes to reduce your workshop scrap to zero.
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