Young’s Modulus of 6061-T6 Aluminum: E, G and Poisson’s Ratio
Need a reliable starting value for a 6061-T6 design? Use the room-temperature elastic constants below, then check temperature, product direction, geometry and weld condition before making a final decision.
6061 aluminum bar stock. Robert.Baruch / Wikimedia Commons, CC BY-SA 3.0.
Start with 69 GPa—then check the conditions.
For an ordinary room-temperature elastic model, 69 GPa and ν = 0.33 are reasonable starting inputs. Use project-specific data when temperature, product direction, welding, compliance limits or safety classification make a few-percent difference important.
Young’s modulus controls axial strain and is part of the EI term that controls beam deflection.
Shear modulus belongs in the GJ term used to estimate shaft twist and shear deformation.
Poisson’s ratio links longitudinal stretching to sideways contraction in the elastic range.
E predicts elastic deformation. Yield strength tells you when permanent deformation begins.
Use this decision table before you freeze the material model
| Design situation | Reasonable starting point | Evidence to collect | Stop and verify when |
|---|---|---|---|
| Room-temperature, elastic FEA | E = 68.9 GPa; ν = 0.33 | Correct unit system and product identity | Plasticity, fatigue, buckling or safety limits control the design |
| Shear or torsion | Derive G ≈ 25.9–26.0 GPa from E and ν | Section geometry, J or torsion constant, joint stiffness | Thin walls, contacts or fasteners dominate the measured twist |
| Welded 6061-T6 assembly | Keep E as a starting elastic value; do not reuse unwelded T6 strength blindly | Weld geometry, HAZ condition, filler, distortion and joint test | The weld or HAZ controls acceptance, fatigue or permanent deformation |
| Hot, cryogenic, directional or contractual work | Use temperature- or direction-specific data | Test method, temperature, orientation, lot and uncertainty | Only a generic handbook number is available for a required acceptance property |
What is the Young’s modulus of 6061-T6 aluminum?
This answer is suitable for many early designs, classroom calculations and first-pass finite element models. It is not a guarantee for every plate, extrusion, direction, batch, weld or temperature.
Published sources may show values from roughly 68.3 to 71 GPa. That does not always mean one source is wrong. Some values are rounded design constants. Others come from a particular test mode, product, direction, temperature or dataset.
| Property | Typical SI value | Common US value | What it controls |
|---|---|---|---|
| Young’s modulus, E | 68.9–69 GPa 68,900–69,000 MPa | About 10.0 Msi 10,000 ksi | Axial strain and bending deflection |
| Shear modulus, G | About 25.9–26.0 GPa | About 3.76–3.77 Msi | Shear deformation and shaft twist |
| Poisson’s ratio, ν | About 0.33 | Dimensionless | Transverse strain during axial loading |
| Bulk modulus, K | About 67.5 GPa | About 9.79 Msi | Volume change under uniform pressure |
The Aluminum Association lists a 10,000 ksi nominal modulus for common 6061-T6 products, while historical NASA data include values around 10.2–10.3 Msi. Treat the table above as a practical engineering starting point, not a lot-specific certificate.
The unit trap that can ruin an FEA model
In an N-mm-MPa unit system, enter 68,900 MPa, not 68.9. Entering 68.9 in a model that expects MPa makes the material 1,000 times too flexible.
Which 6061-T6 elastic property should you use?
Start with the load and the type of deformation you need to predict. Do not choose a property only because its name sounds familiar.
Use Young’s modulus E
A larger E means less elastic strain under the same axial stress. In bending, E works with the section moment of inertia I.
- Tie rods and columns
- Brackets and beams
- Elastic springback estimates
Use shear modulus G
A larger G means less angular distortion under the same shear stress. In torsion, G works with the torsion constant or polar moment J.
- Drive shafts and axles
- Thin-walled tubes
- Shear-sensitive joints
Use Poisson’s ratio ν
When a specimen stretches, it becomes slightly narrower. ν relates that transverse strain to axial strain within the elastic range.
- 3D solid FEA
- Strain-gauge correlation
- Contact and pressure models
E = stress ÷ elastic strain = σ ÷ εUse the slope of the linear elastic region—not the yield strength or ultimate tensile strength.
ν = − transverse strain ÷ axial strainThe minus sign makes ν positive when a tensile specimen gets longer and narrower.
G = E ÷ [2(1 + ν)]For E = 68.9 GPa and ν = 0.33, G ≈ 25.9 GPa.
K = E ÷ [3(1 − 2ν)]For the same inputs, K ≈ 67.5 GPa.
How do you calculate shear and bulk modulus from E and ν?
Enter Young’s modulus and Poisson’s ratio. The tool calculates a mathematically consistent shear modulus and bulk modulus for an isotropic, linear-elastic model.
Defaults are common room-temperature values for wrought 6061-T6.
Use this for preliminary isotropic analysis. A tested anisotropic material model needs direction-specific data instead.
Results update as you type and stay in your selected unit.
Is Young’s modulus the same as strength?
The first straight part of a stress-strain curve is the elastic region. Its slope is Young’s modulus. A steeper slope means less elastic strain under the same stress.
Yield strength answers another question: when does the metal start to deform permanently? Two materials can have similar E values but very different yield strengths.
Why T6 does not make E jump like strength
T6 heat treatment creates strengthening precipitates that make dislocation movement harder. This can raise yield strength and hardness sharply. It does not change the basic atomic bond stiffness by the same multiple, so elastic deflection often remains close to that of other 6061 tempers.
- Use E for elastic deflection and vibration stiffness.
- Use yield strength for the start of permanent deformation.
- Use fatigue, buckling and fracture checks where the load case requires them.
Stress-strain chart: Toiyabe / Wikimedia Commons, CC BY-SA 3.0.
Does T6 heat treatment change 6061-T6 stiffness?
6061-T6 is solution heat-treated and artificially aged. That thermal path controls the precipitate condition that gives the alloy much of its useful strength.
Common handbooks therefore use nearly the same nominal Young’s modulus across several 6061 tempers, even when their yield strengths differ greatly. Precise measured moduli can still shift with condition, product, direction and test method.
For a deflection problem, increasing section depth, adding a rib, shortening a span or improving a joint can have far more effect than changing between 6061 tempers.
6061-T6 heat-treatment sequence based on ASTM B918M-17a. Bob Clemintime / Wikimedia Commons, CC BY-SA 4.0.
How do E, G and ν change real design calculations?
The same material uses different elastic constants depending on whether the part stretches, bends or twists.
500 mm aluminum tie
Load F = 10 kN, area A = 100 mm², E = 68,900 N/mm². The 20 mm width is used to estimate lateral contraction.
Strain = stress / E = 100 / 68,900 = 0.001451
Elongation = strain × L = 0.001451 × 500 = 0.726 mm
Width change = −ν × strain × width ≈ −0.0096 mm
500 mm cantilever
End load F = 100 N. Rectangular section b = 30 mm and h = 20 mm, with the 20 mm dimension acting as the bending depth.
Deflection = F L³ / (3 E I)
= 100 × 500³ / (3 × 68,900 × 20,000)
≈ 3.02 mm
Because deflection changes with L³ and h³, geometry can dominate the material value.
30 mm solid shaft
Length L = 500 mm, torque T = 100 N·m and G = 26,000 N/mm².
Angle = T L / (J G)
= 100,000 × 500 / (79,522 × 26,000)
≈ 0.0242 rad = 1.39°
Maximum shear stress ≈ 18.9 MPa
What values should you enter for a 6061-T6 FEA model?
For a first room-temperature linear-elastic model of wrought 6061-T6, this is a consistent starting set.
N-mm-MPa system
Five checks before trusting the result
Confirm every unit—especially whether the solver expects Pa, MPa, psi or ksi.
Use only two independent elastic constants for an isotropic model.
Check section dimensions, contacts, fasteners, supports and load application.
Upgrade the material model when plasticity, temperature or direction matters.
Represent welds and heat-affected regions with qualified joint data and geometry.
Check units first
68.9 entered into an MPa model is the classic 1,000× error. Also check section thickness and connector compliance.
Look beyond modulus
Fixture motion, bolt slip, contact, local yielding and imperfect supports can make an assembly look softer.
Check mass and joints
Density, attachments, contact stiffness and boundary conditions can shift frequency as much as a small E change.
Question isotropy
Identify plate or extrusion direction, texture, residual stress, local geometry and gauge alignment.
When is 69 GPa not enough for a 6061-T6 design?
Temperature, loading mode, product direction, test method and rounding can explain why credible sources do not all print the same number.
Typical vs design value
A source may publish a measured mean, a rounded nominal value or a conservative design constant. These are not interchangeable labels.
Plate is not every extrusion
Wrought 6061 is often modeled as isotropic, but rolling and extrusion texture can create directional differences important to precise work.
Static vs dynamic modulus
Tension, compression, resonance and ultrasonic methods can report slightly different values because they sample the material differently.
How does temperature change Young’s modulus?
A historical NIST fit for 6061-T6 from 2 K to 295 K gives about 77.1 GPa at 77 K, 73.6 GPa at 200 K and 70.3 GPa at 295 K. These values describe that specific low-temperature dataset, not every commercial product.
At elevated temperature, Young’s modulus falls. Strength and the T6 precipitate condition can also change, often more severely. A hot structure therefore needs a code-approved or validated temperature curve—not the room-temperature 69 GPa value.
Alignment, strain measurement, loading rate, specimen direction and machine compliance all matter.
Aluminum specimen in an Instron machine. Aoscar444 / Wikimedia Commons, CC BY-SA 4.0.
How is Young’s modulus of 6061-T6 measured?
ASTM E111 describes modulus measurements within the elastic region. Small errors in alignment or strain can create a large error in the slope.
- Keep the load centered and minimize bending in the specimen.
- Measure strain on the specimen, not only crosshead motion.
- State tension or compression, temperature and loading direction.
- Use a suitable stress range and a documented slope method.
- Report uncertainty when the number is used for acceptance.
A handbook value is usually enough for early design. Testing becomes more valuable when a few percent changes acceptance, strain correlation, modal performance or a safety limit.
How does welding change a 6061-T6 stiffness model?
Laser or arc welding changes the precipitate condition near the joint. The heat-affected zone can lose a large part of its yield and tensile strength even when the elastic modulus does not fall by the same percentage.
A welded assembly can still become more flexible because of weld geometry, softened zones, distortion, residual stress, joint layout and boundary conditions. Do not assign unwelded T6 strength to every element in the weld and HAZ.
For a qualified welded model
- Identify alloy, temper, thickness, joint type and filler choice.
- Use the governing weld-affected strength rules.
- Represent actual weld geometry and connection stiffness.
- Validate distortion, gap tolerance and target penetration.
Qualify the joint and heat-affected region instead of scaling every property by one factor.
Experimental AC TIG weld on 4 mm 6061 plate. W. S. Yerazunis / Wikimedia Commons, public domain.
Product form, direction, dimensions, processing and required evidence still matter.
Etched 6061-T6 microstructure. Bob Clemintime / Wikimedia Commons, CC BY-SA 4.0.
What should buyers specify when modulus is contractual?
Product standards can control alloy, temper, dimensions, tensile properties and inspection. They do not automatically mean each shipment has a measured E, G or ν value.
Common routes include ASTM B209 for sheet and plate, B221 for extruded products, B211 for bar, rod and wire, and B241 for seamless tube and pipe. The correct route depends on the part you buy.
If modulus is contractual, state:
- Required property and acceptable range
- Test method and current edition
- Temperature and loading mode
- Longitudinal or transverse direction
- Sampling frequency and specimen location
- Uncertainty and acceptance rule
Which test method matches the property you need?
Do not request “a modulus test” without saying which modulus, loading mode, temperature and acceptance purpose you need.
Young’s modulus
Static tension or compression routes for Young’s, tangent and chord modulus. Useful when elastic compliance is the decision.
Poisson’s ratio
Measures axial and transverse strain at room temperature within the proportional range.
Shear modulus
Room-temperature torsion method for structural materials. Alignment, wall thickness and residual stress matter.
Dynamic modulus
Impulse excitation provides a dynamic modulus. Do not assume it must exactly match a static tensile value.
What it may omit
A certificate can confirm alloy, temper, chemistry and tensile properties without reporting a measured E, G or ν.
Validate the real load path
Part-level testing can reveal joint, contact, support and geometry effects that a material coupon cannot reproduce.
Why can measured deflection disagree with a 69 GPa FEA model?
Changing the material modulus should be one of the last steps—not the first guess.
| Symptom | Likely checks | Better next step |
|---|---|---|
| FEA is about 1,000× too flexible | GPa entered into an MPa model | Use 68,900 MPa in an N-mm-MPa system. |
| Assembly is softer than coupon data | Joint slip, fixture motion, contact, fasteners | Measure the full load path and model connector compliance. |
| Bending test gives a low apparent E | Wrong thickness, span or moment of inertia | Measure actual geometry; deflection is highly sensitive to depth. |
| Welded part is more flexible | Distortion, joint geometry, softened HAZ, boundary changes | Use a qualified joint model and test the assembly. |
| Values differ by direction | Product texture, specimen orientation, residual stress | Request longitudinal and transverse data for the actual form. |
| Hot part deflects too much | Room-temperature E reused at elevated temperature | Apply a code-approved or validated temperature-dependent curve. |
Evaluating a 6061 aluminum welding, cleaning or marking application?
Share the alloy, temper, thickness, joint or surface condition, target result and production requirement. Oceanplayer can help plan a process test and equipment direction without pretending that one handbook number replaces a real sample.
Use these pages to connect elastic properties with alloy choice, filler selection, welding behavior and material cost.
What questions do engineers ask about 6061-T6 elastic constants?
Short answers to the questions engineers, buyers and students ask most often.
Are Young’s modulus, elastic modulus and modulus of elasticity the same?
In ordinary uniaxial engineering use, these terms normally refer to E: the slope of the linear elastic stress-strain curve. “Elastic constants” is broader and can also include G, ν and K.
Is 6061-T651 stiffer than 6061-T6?
Do not assume a meaningful design increase in E from the stress-relief suffix alone. T651 can offer better residual-stress control and machining stability, but the same nominal elastic modulus is often used for preliminary calculations.
Why do sources show 68.3, 68.9, 70 or 70.3 GPa?
Values may reflect rounding, source conventions, tension versus compression, temperature, specimen direction, product form or a specific dataset. Values near 69–71 GPa are not automatically contradictory.
Will a mill certificate report Young’s modulus?
Not necessarily. It may report alloy, temper, chemistry, tensile strength, yield strength, elongation, dimensions and traceability without measuring E, G or ν. Add a clear test requirement if modulus is a contractual acceptance property.
Do welded 6061-T6 parts use the same elastic constants as the parent material?
Use the parent-material E as a preliminary elastic input only. Welding changes the local temper and joint geometry, and the heat-affected zone can lose strength. For a qualification or acceptance decision, verify the actual weld, HAZ, distortion and load path instead of assigning one unverified factor.
Which sources support these 6061-T6 values?
Values are labeled by purpose and condition so a handbook number is not mistaken for a universal certificate.
- The Aluminum Association, Aluminum Design Manual 2020 Erratum No. 2 — 10,000 ksi nominal modulus shown for common 6061-T6 products.
- NASA Materials Data Handbook: Aluminum Alloy 6061 — historical design and typical modulus values illustrating source differences.
- ASTM E111-17(2025)e1 — Young’s, tangent and chord modulus testing.
- ASTM E132-17(2025)e1 — Poisson’s ratio at room temperature.
- ASTM E143-20 — shear modulus by room-temperature torsion testing.
- NIST historical 6061-T6 cryogenic properties — polynomial fit for Young’s modulus from 2 K to 295 K; page carries a maintenance warning.
- Hydro Alloy 6061 data sheet — temper, product and weld-region strength guidance.
- MIT OpenCourseWare: Stress-Strain Relations — isotropic relationship between E, G and ν.