Reading data sheets correctly – what aluminium properties really mean

Aluminium is one of the most versatile materials of modern industry. It combines low weight with high strength, corrosion resistance and excellent thermal conductivity. To illustrate the relevance of the characteristic values, a practical example can be given: in aviation, the ratio of strength to weight determines range and safety, while in mechanical engineering the thermal conductivity of heat sinks determines efficiency.

But to select the right alloy and type of processing, a precise understanding of the technical characteristic values in the data sheet is essential. Anyone who processes or designs with aluminium must know what the figures actually say – and what limits they have. Because data sheets provide not only physical properties, but also the basis for safety, quality and sustainability in production.

Structure and significance of an aluminium data sheet

An aluminium data sheet is far more than a list of figures. It contains all essential information on composition, mechanical and physical properties, standards and test conditions. Typically divided into the following sections:

• General information: alloy, material designation, temper (e.g. T6, H111), production method.
• Chemical composition: proportions of aluminium, magnesium, silicon, copper, zinc etc.
• Mechanical characteristic values: tensile strength, proof stress, elongation at break.
• Physical characteristic values: density, thermal conductivity, electrical conductivity.
• Tolerances and dimensions: limit values for thickness, width, flatness, squareness.
• Standards and test methods: references to EN, ISO and ASTM standards.

The data is generally valid for defined tempers and temperature ranges. Deviations can arise from the production process, material batch or test method.

Typical characteristic values in the aluminium data sheet

Alloy	Temper	Tensile strength (MPa)	Proof stress (MPa)	Elongation at break (%)	Density (g/cm³)	Thermal conductivity (W/mK)
EN AW‑1050A	H14	60–100	30–60	30–40	2.71	230
EN AW‑5083	H111	270–330	125–200	10–17	2.66	121
EN AW‑6082	T6	290–340	240–280	8–12	2.70	180
EN AW‑7075	T6	500–560	430–480	7–10	2.81	130

This comparison table shows typical characteristic values of common alloys. It facilitates direct comparison between strength, ductility and thermal conductivity and makes clear why the choice of material always depends on the respective application.

Tensile strength (Rm)

Tensile strength describes the maximum stress a material can absorb before it fails. It is a measure of the load-bearing capacity under tensile stress and is specified in megapascals (MPa). Testing is usually carried out in a standardised tensile test to EN ISO 6892-1, in which a specimen is stretched to breaking point. The higher the Rm value, the stronger the material. However, high strength also means lower ductility, which can lead to cracking during bending or forming operations. A good example is EN AW-7075, which provides high tensile strength for aircraft parts but can barely be cold formed.

Proof stress is the stress at which the material begins to deform permanently. It marks the transition from the elastic to the plastic range. For aluminium it is usually between 50 and 450 MPa. Materials with a high proof stress are more dimensionally stable, but less easy to form. Designers take this value into account when choosing profile thicknesses and fastening elements.

Elongation at break (A)

Elongation at break indicates by what percentage a material extends before it breaks. It is measured in the tensile test and is an indicator of the toughness and energy absorption capacity of a material. A high elongation at break means that the material can be plastically deformed and can dissipate stresses well – an important factor in crash structures, deep-drawn parts or weld seams. Typical values range from 5 % for high-strength types to up to 40 % for soft aluminium types. EN AW‑1050A and EN AW‑5005 are particularly suitable for forming processes, while EN AW‑7075 is more likely to be used in static applications due to its low elongation.

Elongation at break describes how much a material can stretch before breaking. It is a measure of toughness and shows how ductile or brittle a material is. Values above 10 % are considered readily formable; below 5 % the material is described as brittle. In welded structures or bent parts, a high elongation at break is an advantage, as it can absorb stress peaks.

Modulus of elasticity (E)

The modulus of elasticity describes stiffness in the elastic range and thus the ratio of stress to strain. For aluminium it is around 70,000 MPa, regardless of the alloy. This explains why aluminium components deflect more under load than steels. In design this is compensated for by larger cross-sections or ribs. Particularly in load-bearing lightweight components, such as vehicle chassis or machine frames, knowledge of the E modulus plays a central role in dimensioning and vibration analysis.

The modulus of elasticity describes the stiffness of a material. For aluminium it is around 70,000 MPa – significantly lower than for steel. This means that aluminium springs back more, which must be taken into account with large spans or dynamic loads. In design, larger cross-sections are therefore often chosen in order to achieve the same stiffness.

Hardness (HB or HV)

Hardness characterises a material's resistance to the penetration of a test body. It correlates with strength and wear resistance. Aluminium has a range of around 20 to 120 HB. While pure aluminium is soft and easily deformed, heat-treated alloys such as EN AW‑7075 T6 achieve hardness values above 100 HB. Hardness tests according to Brinell or Vickers provide valuable indications of the condition after anodising, coating or milling, since surface hardness influences machinability and scratch resistance. (HB or HV)

The hardness of a material indicates its resistance to plastic deformation. Compared with steel, aluminium is relatively soft (20–120 HB). Alloying and heat treatment can specifically increase hardness, e.g. in EN AW‑7075 or EN AW‑2024.

Density (ρ)

The density of aluminium is around 2.7 g/cm³ and is therefore around one third of the density of steel. It is one of the most important physical characteristic values, as it is directly related to the weight and inertia of a component. In lightweight construction, the low density enables a considerable reduction in moving masses – decisive for energy efficiency and dynamics.

Differences in density arise from the alloy composition: magnesium and silicon lower it slightly, while zinc or copper increase it. In data sheets it is usually specified for 20 °C, as temperature changes cause minor volume fluctuations.

Thermal conductivity (λ)

Aluminium has a high thermal conductivity of typically 120 to 230 W/mK, which makes it a preferred material for thermal management systems. This characteristic value describes how efficiently heat flows through the material. Pure aluminium (e.g. EN AW‑1050A) achieves peak values above 220 W/mK, while heavily alloyed types have lower values due to alloying elements.

In practice, thermal conductivity influences the efficiency of heat sinks, heating elements and housings. It also depends on purity, microstructure and heat treatment condition.

Electrical conductivity

The electrical conductivity of aluminium is between 35 and 40 MS/m, which corresponds to around 60 % of the conductivity of copper. Due to its lower weight and more favourable price, aluminium is nevertheless an economical alternative, especially in the high-voltage and energy sector. In applications such as busbars, cables or motor housings, contact resistance counts alongside conductivity.

Surface oxidation can increase this, which is why coatings or special alloys are frequently used for electrical connections.

Thermal expansion

The linear coefficient of thermal expansion of aluminium is around 23 × 10⁻⁶ 1/K. It indicates how much the material expands with temperature changes. Aluminium therefore expands around twice as much as steel, which must be taken into account in multi-layer constructions or tight fits. In precision applications such as optical devices or electronic housings, temperature-compensated composite solutions are therefore often used. In data sheets this characteristic value is usually specified for a temperature range from 20 °C to 100 °C.

With a density of around 2.7 g/cm³, aluminium is around three times lighter than steel. The low weight makes it ideal for lightweight applications. In practice, density also influences mass inertia, vibration behaviour and energy efficiency – for example in vehicle or aircraft structures.

Practical relevance: characteristic values in combination

In mechanical engineering, these combinations of characteristic values become apparent, for example, in the use of aluminium frames for machine tools, where EN AW‑6082 is preferred due to its combination of stiffness and machinability. In vehicle engineering, on the other hand, EN AW‑7075 is used for chassis components because its high tensile strength reduces weight while at the same time increasing stability. Characteristic values also play a role in façade construction – here EN AW‑5005 ensures clean surfaces and dimensional stability through high ductility and good anodisability. A single characteristic value never describes the overall behaviour of a material. In practice, combinations count:

• High tensile strength + low elongation at break: high strength, but brittle behaviour (e.g. EN AW‑7075)
• Medium strength + high proof stress: balanced ratio for structural components (e.g. EN AW‑6082)
• Low strength + high elongation at break: readily formable, ideal for sheets and drawn parts (e.g. EN AW‑1050A)

Application	Required property	Suitable alloys
Lightweight construction with high strength	High tensile and proof stress	EN AW‑7075, EN AW‑6082
Seawater-resistant constructions	Corrosion resistance, good weldability	EN AW‑5083, EN AW‑5754
Thermally conductive components	High thermal conductivity	EN AW‑1050A, EN AW‑6061
Visible surfaces and façades	Good anodisability, dimensional stability	EN AW‑5005, EN AW‑6063

Understanding tolerances and dimensional deviations

In technical drawings, precise dimensional tolerances apply to aluminium products, regulated in EN 485-4 and EN 755-9. These standards define limit values for:

• Thickness and width tolerances
• Flatness and squareness
• Surface defects and roughness

Small tolerances increase production effort, but significantly influence fit accuracy. For CNC cut pieces, designers should always take into account the intended use and further processing – an optical front panel requires tighter tolerances than a structural component in a machine frame.

Temperature dependence of properties

The mechanical characteristic values of aluminium react sensitively to temperature changes. On heating from around 100 °C, the strength values begin to fall; from 150 °C, up to 30 % of the original tensile and proof stress can already be lost. From around 200 °C, pronounced microstructural changes occur, particularly in precipitation-hardening alloys, which partially lose their hardness and strength.

Engineers must therefore plan suitable safety factors for high-temperature applications in the engine, furnace or electrical engineering sector or switch to heat-resistant alloys. Conversely, at low temperatures – for example in cryogenics or aerospace – strength increases by up to 20 %, although toughness decreases, which can promote brittle fracture. In data sheets, temperature curves or diagrams are often given as guidance and should always be taken into account in material selection.

Test standards and documentation

Reliable data sheets are based on standardised tests. Relevant sets of rules are:

• EN 573: Chemical composition of aluminium alloys
• EN 485: Mechanical properties, dimensions and tolerances
• EN 515: Temper designations (e.g. T6, H111)
• EN ISO 6892‑1: Tensile test on metallic materials
• EN ISO 6506/6507: Hardness testing

Every data sheet should state the test conditions – such as specimen thickness, orientation and ambient temperature. Only then are values truly comparable.

Sustainability and resource efficiency

The interpretation of characteristic values also plays a role in the sustainability context. High strength can reduce material usage, low density reduces transport weight and energy consumption. Aluminium is almost fully recyclable, with mechanical characteristic values barely affected. Secondary aluminium saves up to 95 % energy compared with primary production. In addition, many manufacturers align themselves with international standards such as ISO 14001 (environmental management) or the ASI Performance Standard (Aluminium Stewardship Initiative), which ensure sustainable supply chains and responsible resource use.

The interpretation of characteristic values also plays a role in the sustainability context. High strength can reduce material usage, low density reduces transport weight and energy consumption. Aluminium is almost fully recyclable, with mechanical characteristic values barely affected. Secondary aluminium saves up to 95 % energy compared with primary production.

Future prospects: intelligent material data

With advancing digitalisation, material data is gaining a new strategic role. Modern CAD, CAM and simulation systems now link data sheets directly with component models, enabling engineers to simulate the effects of loads, temperature and production processes already during the development phase. In future, AI-supported systems will recognise patterns from huge material databases, predict use cases and automatically suggest suitable alloys.

In addition, cloud-based platforms enable real-time measured values to be compared with target characteristic values from the data sheet – a step towards self-learning, adaptive material selection. As a result, material data becomes not just static information, but an active component of intelligent production processes and digital twins.

Reading, understanding and applying characteristic values

Figures are only as good as their understanding – anyone who interprets characteristic values correctly makes better technical decisions. An aluminium data sheet is not a theoretical document, but a practical tool for engineers, buyers and manufacturing companies.

Anyone who understands the meaning of the individual values can select materials safely, minimise risks and optimise costs. What is decisive is to consider characteristic values not in isolation, but in combination with standards, temperature, tolerances and application conditions. In this way, a data sheet becomes a genuine decision-making aid for quality and precision.

Get support with your selection or configure your aluminium sheet directly on the basis of the right characteristic values.

FAQ

What is the difference between tensile strength and proof stress? Tensile strength indicates the maximum load up to breaking point, proof stress the point from which the material deforms permanently.

Why do characteristic values differ despite the same alloy? Because temper, temperature, specimen orientation and production method have a decisive influence on the measurement results.

How important is the modulus of elasticity in practice? It determines the deflection and vibration susceptibility of components – particularly relevant with large spans or thin-walled structures.

Which standards apply to aluminium data sheets? The essential ones are EN 573, EN 485, EN 515, EN ISO 6892‑1 and, in addition, EN ISO 6506 and EN ISO 6507.

How can sustainability be assessed via characteristic values? Density, strength and recyclability of aluminium enable an ecological assessment – low weight and high stability save energy and material resources.