Decoding the H-Temper: H32 vs H34 vs H18 Aluminum States Explained

Introduction: What Does the "H" Mean?

In the world of aluminum, the alloy grade (like 5052 or 5083) tells you what the metal is made of. But the temper — the letters and numbers that follow the alloy designation — tells you how the metal was processed and what mechanical properties it offers. For non-heat-treatable aluminum alloys (such as the 1xxx, 3xxx, and 5xxx series), the H temper is the most common designation.

Unlike heat-treated T-tempers (which achieve strength through thermal processing), H-tempers achieve their properties through strain hardening — also known as work hardening or cold working. This involves mechanically deforming the metal through processes like rolling, stretching, or drawing, which increases strength and hardness but typically reduces ductility.

In short: the H series achieves strength through "physical exercise" (work hardening), while the T series develops strength through "internal transformation" (heat treatment).

Gwangyang Aluminum (GYAL) , a leading South Korean aluminum manufacturer, supplies a full range of H-temper products, including H32, H34, and H18, across multiple alloys. With IATF 16949 certification and full mill traceability, Gwangyang Aluminum ensures consistent quality across all tempers and applications.

How to Read an H-Temper Designation

An H designation is followed by two or three digits:

The first digit indicates the basic treatment sequence:

• H1X – Strain-hardened only (no additional heat treatment)

• H2X – Strain-hardened and then partially annealed

• H3X – Strain-hardened and then stabilized by low-temperature heat treatment

• H4X – Strain-hardened and then painted or lacquered

The second digit indicates the degree of hardness — the higher the number, the greater the strength and hardness, and the lower the ductility:

• 2 = ¼ hard

• 4 = ½ hard

• 6 = ¾ hard

• 8 = full hard (4/4 hard)

Understanding these two digits is the key to decoding any H-temper.

H32 Temper: Strain-Hardened and Stabilized – ¼ Hard

Definition: H32 means the aluminum has been strain-hardened and then stabilized by low-temperature heat treatment, achieving a hardness level of ¼ hard.

Why Stabilization Matters: The stabilization step (the "3" in H32) is particularly important for 5xxx series alloys containing magnesium. It improves resistance to stress corrosion cracking and ensures stable mechanical properties over time.

Key Characteristics:

• Moderate strength

• Good formability and ductility

• Excellent corrosion resistance, especially in marine environments

• Good weldability and cold formability

• Most commonly produced temper in sheet form

Typical Mechanical Properties (5052-H32):

• Tensile Strength: 214–280 MPa

• Yield Strength: ~193 MPa

• Elongation: 12–18%

Common Applications:

• Ship hull and deck components

• Aircraft fuel tanks and pressure vessels

• Trailer components

• Chemical tanks

• General sheet metal work

• Marine and industrial applications

When to Choose H32: Choose H32 when you need a balance of strength and formability. It is the go-to temper for applications requiring moderate strength, excellent corrosion resistance, and the ability to be formed into complex shapes without cracking.

H34 Temper: Strain-Hardened and Stabilized – ½ Hard

Definition: H34 means the aluminum has undergone more extensive strain hardening than H32, followed by stabilization, achieving a hardness level of ½ hard.

Key Characteristics:

• Higher strength than H32 (approximately 10–15% higher)

• Slightly reduced ductility and formability compared to H32

• Excellent corrosion resistance

• Good weldability

Typical Mechanical Properties (5052-H34):

• Tensile Strength: 260–310 MPa

• Yield Strength: ~193–220 MPa

• Elongation: 6–12%

Common Applications:

• Boat hulls and ship parts exposed to saltwater

• Load-bearing decks

• Fuel tanks

• Aircraft and automotive components

• Structural support applications

• High-strength automotive parts like door frames and reinforcement beams

• 3C electronics enclosures requiring higher rigidity

When to Choose H34: Choose H34 when you need higher strength than H32 can provide, but still require reasonable formability. It is ideal for load-bearing applications where strength is a priority.

H18 Temper: Strain-Hardened – Full Hard (4/4 Hard)

Definition: H18 means the aluminum has been strain-hardened to the maximum level — fully hardened, or 4/4 hard. Unlike H32 and H34, H18 does not include stabilization or annealing steps — it is simply strain-hardened to its maximum capacity.

How It‘s Achieved: The full-hard condition (H18 temper) is typically obtained with cold work equal to about 75% reduction in area.

Key Characteristics:

• Maximum strength among H-tempers

• Lowest ductility — least formable of the three

• Hardest surface

• Reduced corrosion resistance compared to stabilized tempers (due to lack of stabilization)

Typical Mechanical Properties:

• Tensile Strength: Varies by alloy; for 8011, up to 150–180 MPa

• Hardness: Brinell 44+ (depending on alloy)

• Significantly reduced elongation

Common Applications:

• Pharmaceutical foil (PTP blister lidding)

• Applications where maximum strength and hardness are required

• Products that will not undergo further forming

• Thin-gauge products like foil and certain sheet applications

When to Choose H18: Choose H18 when you need maximum strength and hardness and no further forming will be performed. Its limited ductility makes it unsuitable for bending, stamping, or deep drawing.

Comparison Table: H32 vs H34 vs H18

Choosing the Right Temper for Your Project

Select H32 when:

• You need a balance of strength and formability

• Your application requires bending, stamping, or deep drawing

• Excellent corrosion resistance is critical (marine environments)

• You‘re working with sheet metal for general fabrication

Select H34 when:

• You need higher strength than H32

• Your application involves load-bearing components

• You can accept slightly reduced formability

• You need structural support or automotive reinforcement parts

Select H18 when:

• You need maximum strength and hardness

• No further forming will be performed

• Your application involves thin-gauge products like foil or specialized sheet

Gwangyang Aluminum: Your Partner for All H-Tempers

Gwangyang Aluminum (GYAL) is a leading South Korean aluminum manufacturer with a comprehensive range of H-temper products:

Available Tempers: F, O, H111, H12, H14, H16, H18, H22, H24, H26, H28, H32, H34, H36, H38

Key Specifications:

Thickness: 0.2 – 6.35 mm

Width: 900 – 1524 mm

Standards: AMS 4015 (O), AMS 4016 (H32), AMS 4017 (H34)

Certifications: IATF 16949, ISO, ASTM B209

Quality Assurance: Gwangyang Aluminum maintains full mill traceability and automotive-grade quality management systems, ensuring consistent performance across all tempers. The company‘s 5052 H32 and H34 aluminum sheets are widely recognized for their excellent corrosion resistance and strength, making them ideal for marine, automotive, and industrial applications.

Why Choose Gwangyang Aluminum:

Factory-direct supply with wholesale pricing

Full range of tempers in stock

IATF 16949 certified automotive-grade quality

Complete traceability on every coil

Fast delivery to global markets

FAQ – H32 vs H34 vs H18 Aluminum States

Q1: What is the difference between H32 and H34?
A: H34 undergoes more extensive strain hardening than H32, resulting in higher strength (approximately 10–15% higher) but slightly lower formability. H32 is ¼ hard; H34 is ½ hard.

Q2: Why is H18 not stabilized like H32 and H34?
A: H18 is a pure strain-hardened temper (H1X) without stabilization or annealing. It achieves maximum strength through cold working (about 75% reduction in area) but has the lowest ductility.

Q3: Which temper is best for marine applications?
A: H32 is the most commonly used temper for marine applications, offering an excellent balance of strength, formability, and corrosion resistance. H34 is also suitable for load-bearing marine components.

Q4: Can H18 be formed or bent?
A: H18 has very limited formability due to its maximum hardness. It is typically used in applications where no further forming is required.

Q5: What does "¼ hard" and "½ hard" mean?
A: These refer to the degree of strain hardening. ¼ hard (H32) means the material has been work-hardened to 25% of its maximum hardness capacity; ½ hard (H34) means 50%; 4/4 hard (H18) means 100% — fully hardened.

Q6: Does Gwangyang Aluminum supply all three tempers?

A: Yes. Gwangyang Aluminum supplies H18, H32, H34, and many other H-tempers across multiple alloys.

Conclusion

Understanding H-tempers is essential for selecting the right aluminum for your application. H32 offers the best balance of strength and formability — the workhorse of the H-tempers. H34 delivers higher strength for load-bearing applications. And H18 provides maximum hardness for applications where no further forming is required.

Gwangyang Aluminum supplies all three tempers with full mill traceability, IATF 16949 certification, and automotive-grade quality, ensuring you get the right material for your specific requirements.

Contact Gwangyang Aluminum for your H-temper aluminum needs. Whether you require H32 for marine applications, H34 for structural support, or H18 for specialized sheet products, Gwangyang Aluminum has the inventory, quality, and expertise to deliver.

Gwangyang Aluminum Industry Co., Ltd

Phone: +82 (0)61-762-6699

Email: gwangyangaluminum@gmail.com

Website: www.gyal.co.kr

Factory Address: 266 Sepungsandan Road, Gwangyang-Eub, Gwangyang-Si, Jeollanam-Do, Republic Of Korea