Aluminium I-Beam Profile 40 x 40 mm Structural H-Section Extrusion

OEM / ODM Available Free Sample Available Mill certificate to EN 10204 3.1 on request, RoHS and REACH declarations, structural calculation on request

Aluminium I-beam (H-section) 40 x 40 mm in 6063-T5. Concentrates material in the flanges for maximum bending stiffness per unit weight. I approx. 15.8 cm4. For structural beam applications.

Wholesale Price Quoted per metre against section, finish, machining and quantity per per metre

Material	Aluminium
Alloy Grade	6063-T5
Temper	T5
Section Size	I-beam (H-section), 40 mm flange x 40 mm web
Slot	No T-slots; connections via flange/web through-bolts or external clamps
Length	6 m stock, cut to drawing to +/-0.5 mm
Tolerance	EN 755-9 / GB/T 6892, wall +/-0.15 mm
Surface	Mill finish / clear anodised / black anodised
MOQ	Made to order; small trial lengths available from stock offcuts
Lead Time	Typically 2 to 3 weeks for mill finish, about a week longer for anodising; drilled and stiffened beams add time
Loading Port	Shanghai, Ningbo, Qingdao
Supply Ability	Extrusion capacity for standard and custom I-beam dies, with in-house cutting, drilling and anodising
Payment Terms	T/T 30 per cent deposit, balance against copy of bill of lading; L/C at sight for larger orders
Trade Terms	FOB, CIF, CFR, EXW
Certifications	Mill certificate to EN 10204 3.1 on request, RoHS and REACH declarations, structural calculation on request

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Cross section of the aluminium I-beam (H-section). Material is concentrated in the top and bottom flanges, giving high bending stiffness about the strong axis. The web is thinner, connecting the flanges and carrying shear.

01What is an aluminium I-beam?

What is an I-beam and why is it shaped that way?

An I-beam (also called an H-section) is a structural profile shaped like the letter I: two horizontal flanges (top and bottom) connected by a vertical web. The flanges carry bending tension and compression, and the web carries shear. By concentrating material in the flanges — where it is furthest from the neutral axis — the I-beam gets maximum bending stiffness per unit of material. It is the most efficient shape for a beam that carries a load perpendicular to its axis.

How does it compare to a square tube of the same weight?

A 40 x 40 mm I-beam at 2.2 kg/m has a second moment of area of about 15.8 cm4. A 40 x 40 mm square tube at the same 2.2 kg/m has about 7.7 cm4. The I-beam is about twice as stiff in bending about the strong axis, for the same weight of aluminium. The trade-off is that the I-beam is weaker in torsion and has no T-slots for mounting accessories.

Why not use I-beams for everything then?

Because the I-beam only wins in one direction. About its weak axis (the flange width), the I is only about 2.0 cm4 — eight times less than the strong axis. It has no slots for T-slot nuts, so connections need brackets or through-bolts. And it has low torsional stiffness compared to a closed tube. It is a beam, not a frame member.

The I-beam section: 40 mm flange width, 40 mm web height. Material is in the flanges, not the web. The strong bending axis is horizontal (through the flanges).

02Section data

Item	Value	Note
Flange width	40 mm	the horizontal dimension
Web height	40 mm	the vertical dimension, flange face to face
Flange thickness	approx. 3.0 mm	the material in the flanges
Web thickness	approx. 2.5 mm	the material connecting the flanges
I (strong axis, cm4)	approx. 15.8	about the horizontal neutral axis
I (weak axis, cm4)	approx. 2.0	about the vertical neutral axis
Ratio strong/weak	approx. 7.9	highly directional
Weight	approx. 2.2 kg/m	same as a 40×40 standard-wall square tube
Alloy	6063-T5	EN AW-6063
Standard	EN 755-9 / GB/T 6892	wall tolerance +/-0.15 mm
Length	6 m stock	cut to drawing to +/-0.5 mm

The I and weight figures are derived from the published 40 x 40 mm I-beam section in the same alloy. The strong-axis I is about twice that of a 40 x 40 square tube at the same weight, and about 2.7 times that of a 40 x 40 standard T-slot profile. Treat as approximate until a certified calculation is required.

03Why the I-beam is efficient in bending

Bending stiffness is driven by the second moment of area (I), which measures how far the material is from the neutral axis. The further the material, the higher the I, and the stiffer the beam.

In a square tube, the material is distributed evenly around the perimeter, so some of it is near the neutral axis (where it does little for bending) and some is far from it (where it does a lot). In an I-beam, all the material is either in the flanges (far from the axis) or in the web (carrying shear, near the axis). The flanges do almost all the bending work, and the web does the shear work.

For a 40 mm deep section, the flange material sits at +/-20 mm from the neutral axis. In a square tube, the material near the corners is also at +/-20 mm, but the material near the centre of each face is at +/-10 mm or less. The I-beam puts nothing in the low-efficiency zone.

Section	Weight (kg/m)	I strong (cm4)	I per kg (cm4 per kg/m)
40×40 I-beam	2.2	15.8	7.2
40×40 square tube (std wall)	2.2	7.7	3.5
40×40 T-slot profile (std)	1.49	5.8	3.9
40×40 T-slot heavy wall	2.35	7.2	3.1

The I-beam gives 7.2 cm4 per kg/m, roughly twice the efficiency of any square or slotted section. That is the structural argument for the I-beam: if your application is a beam carrying a bending load, it is the most material-efficient choice.

04What the I-beam cannot do

The I-beam’s efficiency comes at a cost. Three things it does poorly:

Property	I-beam	Square tube	Why the I-beam is worse
Torsional stiffness	low	high	open section, the web does not close the loop
Weak-axis bending	2.0 cm4	7.7 cm4	flanges are narrow, no material on the sides
Slot nut mounting	impossible	yes	no T-slots; connections need brackets or through-bolts
Multi-directional load	poor	good	only good for load in the strong-axis direction

The I-beam is a beam, not a frame member. It is designed to carry a load perpendicular to its axis, in a known direction. If the load direction is unknown or multi-directional, a square tube is a better choice. If the application needs T-slot accessories, use a T-slot profile instead.

05Connections: brackets and through-bolts, not slot nuts

The I-beam has no T-slots, so connections are made with external brackets bolted through the flanges, or through-bolts that pass through drilled holes in the web or flange. Three common connection methods:

Flange through-bolts: drill through both flanges and bolt a bracket or a plate to the outside. This is the strongest method and carries the highest load.
Web bolts: drill through the web and bolt a bracket to the side. Weaker than flange bolts, but does not project beyond the flange width.
Clamp fittings: an external clamp grips the flange from outside. Fast to install, lower load capacity, no drilling needed.

06I-beam vs square tube: choosing the right section

Choose the I-beam

The member is a beam carrying a known-direction bending load
Material efficiency matters (lightweight structures, long spans)
The load is perpendicular to the beam axis, in one direction
You do not need T-slot accessories along the member
Torsional stiffness is not required

Choose the square tube or T-slot profile

The load direction is unknown or multi-directional
You need T-slot nuts and sliding fittings
Torsional stiffness matters (twisting frames)
The member is part of a frame, not a standalone beam
You want a simpler connection system (slot nuts, no drilling)

07Applications: where the I-beam earns its place

Long-span beams where deflection is the limiting factor: conveyor support beams, roof purlins, platform walkways.
Lightweight structures where material efficiency matters: aerospace ground equipment, portable platforms, vehicle frames.
Solar panel support rails: the I-beam carries the panel weight and wind load efficiently, with brackets bolted to the top flange.
Structural beams in aluminium frames: where a steel I-beam would be over-specified but a T-slot profile is too weak.
Material handling guides and supports: overhead conveyor supports, lift guides, sliding track supports.

08Failure modes to design out

What goes wrong	Why it happens	Design it out by
Beam buckles sideways (lateral-torsional)	the I-beam has low weak-axis stiffness and low torsional stiffness	add lateral restraint at intervals; or use a wider flange section
Web buckles under shear	the 2.5 mm web is thin and can buckle under high shear	add web stiffeners (ribbed or welded plates) at support points
Flange bolt pulls through	the 3.0 mm flange is too thin for a countersunk bolt head	use a washer on both sides; or use a flange nut; or specify thicker flange
Beam oriented on the weak axis	the I-beam looks similar from both ends and can be rotated 90 degrees	mark the strong axis on the drawing and the beam
Joint at the end of the beam fails	the end connection carries the reaction force, which can be high	use a bearing plate or a bolted end cap; do not rely on a single bolt

09What to check before you order

Procurement checklist for the I-beam

Confirm the beam orientation: which direction is the load, and which way is the strong axis. Put it on the drawing.
Confirm the span and the deflection limit: the I is 15.8 cm4; calculate the expected deflection before ordering.
Confirm the connection method: flange through-bolts, web bolts, or external clamps. Specify hole positions on the drawing.
Confirm whether web stiffeners are needed at support points.
Confirm the finish: mill for structural, anodised for corrosion.
Confirm the alloy: 6063-T5 is standard; 6061-T6 for higher-strength structural applications.

10Terms used on this page

Flange: The horizontal top and bottom parts of the I-beam. They carry bending tension and compression.
Web: The vertical part of the I-beam connecting the flanges. It carries shear.
Strong axis: The direction about which the I-beam has its highest second moment of area (the horizontal axis through the flanges).
Weak axis: The direction about which the I-beam has its lowest second moment of area (the vertical axis through the web).
Lateral-torsional buckling: A failure mode where the beam twists and moves sideways under load, because the weak-axis stiffness and torsional stiffness are low.
Second moment of area: A measure of how material is distributed about the neutral axis, in cm4. Higher means stiffer in bending.

11Questions buyers ask

Can I use T-slot nuts on an I-beam?

No. The I-beam has no T-slots. Connections use through-bolts in the flanges or web, or external clamp fittings.

What is the difference between an I-beam and an H-beam?

They are the same shape. ‘I-beam’ and ‘H-section’ are interchangeable terms. The naming convention varies by region and standard.

Is it as strong as a steel I-beam?

No. Aluminium is about one-third the stiffness of steel. A 40 mm aluminium I-beam replaces a much smaller steel beam, not an equal-size one. The advantage is weight: aluminium is one-third the density.

Can it be anodised?

Yes. Clear and black anodised are standard. For structural applications, mill finish is usually sufficient unless corrosion is a concern.

What alloy is it supplied in?

6063-T5 as standard. 6061-T6 is available for higher-strength structural applications; it has about 50 per cent higher yield strength but a poorer surface finish.

What is the minimum order quantity?

Extrusion is made to order. Small trial lengths from stock; production runs quoted by the metre or by the tonne.

What we need to quote this section

The section drawing or the I-beam reference (flange width, web height).
The cut length for each beam and the number of beams.
The connection method: flange through-bolts, web bolts, or external clamps. Specify hole positions if known.
The finish: mill, clear anodised, or black anodised.
The alloy: 6063-T5 standard or 6061-T6 for higher strength.
The annual or per-order quantity, in metres or in pieces.

Send those six items and the quotation comes back with the extrusion price, the cutting and machining charge, the finish surcharge and the lead time. Browse the full aluminium profile catalogue and the strut profiles range for related sections.

Need this beam quoted against your own drawing?

Send the section, the span, the connection method and the finish. We quote extrusion, cutting, drilling and anodising as separate lines.

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