H32 temper aluminium sheet
Walk into any fabrication shop that works with aluminium, and you will notice an interesting pattern: whenever parts need modest strength, predictable bendability, and stable dimensions after forming, the conversation almost inevitably drifts toward H32 temper aluminium sheet. It sits in a quiet middle ground—neither soft and prone to denting like fully annealed material, nor stubborn and crack-prone like heavily strain-hardened tempers.
Thinking about H32 through a purely theoretical lens can make it sound abstract: half-hard, strain-hardened, then partially annealed. But the real story of H32 temper aluminium sheet is about control—of strength, of formability, of residual stress, and ultimately of risk on the shop floor and in the field.
What “H32” Really Means in Practice
The “H” in H32 is short for “strain-hardened.” That tells you the sheet has been cold worked—rolled, drawn, or otherwise mechanically deformed at relatively low temperature to increase strength by rearranging and locking dislocations in the crystal lattice.
The “3” indicates the material is strain-hardened and then stabilized or partially annealed. This heat exposure reduces some of the internal stresses and restores a portion of ductility, while intentionally keeping most of the cold-worked strength.
The “2” signifies the specific degree of strain hardening—roughly equivalent to a “half-hard” condition in traditional metalworking language. Not fully hard, not quarter-hard: that middle discipline where the material behaves predictably under forming and service loads.
In more practical terms:
- Strength is significantly higher than fully annealed (O temper) material.
- Ductility remains sufficient for most bending and moderate forming operations.
- Mechanical properties are stable enough for repeatable production, with less risk of distortion during cutting, welding, or further processing.
The Alloys Most Often Seen in H32
H32 is not a “one-alloy” story; it describes the temper, not the chemistry. Yet in industry, some alloy-temper pairings appear again and again. The most common H32 aluminium sheets are in the 3xxx and 5xxx series:
- 3003-H32: A classic manganese alloy, non-heat-treatable, known for excellent corrosion resistance and very good formability. Widely used in HVAC, cookware, panels, and general fabrication.
- 3004-H32 and 3105-H32: Variants with slightly higher strength and similar corrosion behavior.
- 5052-H32: A magnesium-based alloy, non-heat-treatable, with notably higher strength and very good corrosion resistance, including in marine and slightly more aggressive environments.
These non-heat-treatable alloys gain their strength primarily from solute atoms (Mn or Mg) and strain hardening, not from precipitation hardening. That’s why the H temper is so crucial: it is the main lever to control strength levels.
A typical chemical composition range for two common examples is:
3003 Aluminium (typical range, wt%):
- Mn: 1.0–1.5
- Cu: 0.05–0.20
- Si: ≤ 0.6
- Fe: ≤ 0.7
- Zn: ≤ 0.10
- Others (each): ≤ 0.05
- Others (total): ≤ 0.15
- Al: Balance
5052 Aluminium (typical range, wt%):
- Mg: 2.2–2.8
- Cr: 0.15–0.35
- Si: ≤ 0.25
- Fe: ≤ 0.40
- Cu: ≤ 0.10
- Mn: ≤ 0.10
- Zn: ≤ 0.10
- Others (each): ≤ 0.05
- Others (total): ≤ 0.15
- Al: Balance
These chemistry windows are governed by standards such as ASTM B209, EN 485, and related specifications. They ensure that when you specify 3003-H32 or 5052-H32, you are not playing a guessing game about what is in the metal.
Mechanical Behavior: Not Too Soft, Not Too Brittle
The mechanical profile of H32 temper is what draws so many design engineers to it. Consider 3003-H32 and 5052-H32 as representative:
Typical room-temperature properties (sheet thickness-dependent, per ASTM B209 ranges):
3003-H32
- Tensile strength: ~130–180 MPa
- Yield strength (0.2% offset): ~110–160 MPa
- Elongation (50 mm gauge): ~8–20%
5052-H32
- Tensile strength: ~210–260 MPa
- Yield strength (0.2% offset): ~130–200 MPa
- Elongation (50 mm gauge): ~7–14%
The here is balance. In H32, you rarely get the highest possible strength that the alloy could deliver in a harder temper. Instead, you get a combination: enough strength for load-bearing panels, enclosures, housings, and light structural components, but with sufficient bendability and resistance to cracking during forming.
This equilibrium is especially valuable where:
- Parts must be bent on relatively tight radii.
- Multiple forming operations occur in sequence.
- Cosmetic appearance matters, and surface cracking or orange peel is unacceptable.
- Weldability is required without severe property loss in the heat-affected zone.
How H32 Temper Is Created: Controlled Strain and Heat
From a processing standpoint, H32 is the product of deliberate restraint. The mill first cold works the sheet to increase strength beyond what the final temper will require. That over-hardening step introduces dislocations, internal stresses, and residual strain.
Next comes a controlled thermal exposure, often called “stabilizing” or “partial annealing.” The temperature and time are chosen to:
- Reduce residual stresses that would cause springback, warpage, or dimensional instability.
- Rebalance ductility and toughness by allowing limited recovery and partial recrystallization.
- Avoid dropping strength back to the soft O temper.
The exact thermal cycle is tuned for alloy and thickness. For a fabricator, the important takeaway is that H32 sheets arrive with reasonably uniform properties throughout the coil or plate, which simplifies bending allowances, punch tooling design, and forming simulation.
Standards, Dimensions, and Tolerances: What Buyers Should Ask For
Specifying “H32 temper aluminium sheet” without context invites surprises. A more robust specification references standards and tolerances:
- Use ASTM B209 or the relevant EN/ISO standard to define alloy, temper, mechanical properties, and permitted variations.
- State dimensional ranges: thickness, width, length, flatness tolerance, and edge conditions (mill edge vs. slit edge).
- Clarify surface quality: mill finish, brushed, pre-painted, anodizing-quality if applicable.
H32 temper is particularly sensitive to bending radius. That is where design and standards interact. Many fabricators rely on minimum inside bend radius guidelines, often expressed as multiples of sheet thickness. For example, a 5052-H32 sheet might tolerate an inside bend radius around 1.0–1.5 times the thickness for 90° bends across the rolling direction, but that value can tighten or relax depending on exact property levels, bend orientation, and tooling quality.
As a buyer or designer, you influence success by:
- Requesting test certificates (mill test reports) confirming mechanical properties and chemistry.
- Being explicit if your geometry requires tighter-than-normal bend radii or complex draw forms.
- Aligning your bending direction thoughtfully with respect to the rolling direction whenever possible.
Where H32 Sheets Earn Their Keep
The value of H32 temper reveals itself in the kinds of failures it helps you avoid rather than dramatic performance extremes it showcases. In many real-world applications, H32 is chosen to prevent these problems:
- Cracks on outside bend surfaces during forming operations.
- Excessive denting or deformation in service from minor impacts.
- Unpredictable springback that leads to poor fit-up or misaligned assemblies.
- Dimensional drift during light welding or spot heating.
Common application areas include:
- Enclosures and housings for equipment, where panels must be stiff yet formable.
- Vehicle bodywork, trailer panels, and toolboxes, especially in 5052-H32.
- Architectural cladding, fascia, and soffits, when moderate strength and good corrosion resistance are needed.
- HVAC ducting, covers, and brackets in 3003-H32.
- Marine and coastal hardware, tanks, and small structures in 5052-H32, where corrosion resistance is a daily concern.
In many of these uses, the designer could theoretically specify a harder temper to gain more strength. But the risk of cracked bends and inconsistent forming quickly outweighs that theoretical benefit. H32 acts as a compromise that keeps fabrication robust and predictable.
The Subtle Chemistry–Temper Partnership
One of the distinctive aspects of H32 is how subtly chemistry and temper interact. The magnesium in 5052, for example, boosts solid-solution strengthening and enhances strain-hardening response. That means the same H32 designation in 5052 delivers noticeably higher strength than H32 in 3003, even though both are “half-hard, strain-hardened and stabilized.”
Manganese in 3003 improves corrosion resistance and slightly elevates strength compared with pure 1xxx alloys, but its contribution to strain-hardening behavior differs from magnesium’s. The result: 3003-H32 remains very forgiving in deep draws and complex shapes, while 5052-H32 leans more toward structural applications where loads and environments are harsher.
this is crucial when replacing one alloy with another. Swapping 3003-H32 for 5052-H32 is not just an upgrade in strength; it can change:
- Bend radii requirements.
- Welding behavior and heat-affected zone softening.
- Corrosion performance in chloride-laden or alkaline environments.
- Surface response to anodizing or coating.
A Temper Defined by Reliability
From a unique vantage point, H32 temper aluminium sheet is less about boasting peak performance and more about engineering stability. It is the temperamentally balanced material that allows production lines to keep moving, tools to last longer, and designs to meet their tolerances over thousands of cycles.
In the language of standards, H32 is only a three-character suffix. On the shop floor and in finished products, it is a quiet form of risk management: a temper that combines controlled strain-hardening, carefully limited heat exposure, and compositionally stable alloys to deliver a sheet that behaves as expected today, tomorrow, and far down the production run.
For designers and procurement engineers, recognising that quiet discipline—and specifying H32 with a clear of alloy, standards, and forming requirements—is often the difference between a project that works on paper and one that works consistently in metal.
