3mm Thickness Aluminium Sheet Plate 6061 Alloy

02/17 2026

3mm Thickness Aluminium Sheet Plate 6061 Alloy: The "Everyday Engineer's" Sweet Spot

A 3mm 6061 aluminium sheet plate is easy to underestimate. It doesn't look exotic, it isn't marketed as a high-temperature superstar, and it doesn't carry the "ultra-high-strength" aura of aerospace-only alloys. Yet in real manufacturing, it often becomes the most practical, most frequently reordered material on the shop floor. Think of it as the alloy you reach for when the project needs to be strong, clean, weldable, corrosion-resistant, and reliably available-without demanding special handling or fragile process windows.

At 3mm thickness, 6061 lives in a particularly useful middle zone: thin enough to cut, bend, machine, or drill efficiently, but substantial enough to hold shape, resist denting, and support load without feeling "tinny." It's the thickness that designers use when they want a panel to feel solid in the hand, an enclosure to stay square, or a bracket to remain stiff without becoming heavy.

What 6061 Really Means in Daily Use

6061 is an Al-Mg-Si alloy, and that combination matters. Magnesium and silicon form Mg₂Si, which is the core strengthening mechanism when the alloy is properly heat treated. In practical terms, this gives 6061 a trustworthy balance of strength and corrosion resistance, while keeping it friendly to welding and machining.

Customers often compare 6061 with 5052. A simple way to see the difference is this: 5052 is a corrosion champion and bends beautifully, while 6061 is the "structural all-rounder" with noticeably higher strength after heat treatment and better performance for precision machined parts. If your 3mm sheet is doing more than simply covering something-if it's supporting, locating, framing, or mounting-6061 becomes the logical choice.

Typical Parameters for 3mm 6061 Aluminium Sheet/Plate

While exact values depend on temper, thickness tolerance, and the producing mill, the following parameters are commonly requested by buyers and quoted by suppliers.

Product form
3mm aluminium sheet/plate, 6061 alloy, mill finish or coated/anodizing-ready surface

Common tempers
6061-T6, 6061-T651, 6061-T4, 6061-O

Density
Approx. 2.70 g/cm³

Mechanical properties (typical reference)
These are widely referenced typical values; actual certification should rely on the mill test certificate.

• 6061-T6 / T651: tensile strength around 290–310 MPa, yield strength around 240–276 MPa, elongation often 8–12%
• 6061-T4: tensile strength around 180–240 MPa, yield strength around 110–150 MPa, higher elongation for forming
• 6061-O: much lower strength, maximum formability

Thickness tolerance and flatness
Often governed by the applicable standard and mill capability; tighter tolerances are available upon request, especially for CNC-fixtured parts and high-appearance panels.

Surface options
Mill finish, PVC film protected, brushed, anodizing-quality, or pre-painted depending on application.

Implementation Standards You'll See on Purchase Orders

For international trade and engineering documentation, 6061 sheet/plate is frequently supplied to one or more of the following standards. The right standard is not just paperwork-it defines chemistry limits, mechanical properties, and tolerances that affect downstream processing.

ASTM standards (common in North America and many export projects)

• ASTM B209: aluminium and aluminium-alloy sheet and plate
• ASTM B221: extruded bars, rods, wire, profiles (useful when matching sheet with extrusions)

EN standards (common in Europe and projects referencing EN documents)

• EN 485: sheet, strip and plate-technical conditions for inspection and delivery, mechanical properties, tolerances
• EN 573: chemical composition

GB standards (common in China and some Asia-based sourcing)
Equivalent GB/T series may apply depending on supplier; confirm with the mill for the exact designation on the certificate.

If your job involves certification, always request the mill test certificate showing heat number, chemical composition, and mechanical properties.

Tempering and Heat Treatment: Why It Changes Everything

Many buyers say "6061 is strong," but the more accurate statement is "6061 becomes strong when you choose the right temper."

T6
Solution heat-treated and artificially aged. This is the go-to temper when stiffness and load-bearing matter. For 3mm parts used in frames, brackets, mounting plates, jigs, guards, and structural panels, T6 is often the default.

T651
T6 plus stress relieving by stretching. This matters when you plan to machine the sheet into precision parts. Stress relief helps reduce warping after milling, pocketing, or removing material. If you're cutting complex shapes from 3mm plate and expect them to stay flat, T651 is worth requesting.

T4
Solution heat-treated and naturally aged. This is often chosen when forming or bending is more demanding. You get better ductility than T6, and some shops form in T4 and then age to higher strength if the process allows.

O temper
Annealed. This is for maximum formability and minimal strength requirements. It's less common for structural uses but valuable for deep forming or tight-radius work.

A helpful mindset is to treat temper as a "process setting." It should match what happens next: bending, welding, machining, or service loading.

Corrosion Resistance and Weldability: Practical Advantages

6061 performs well in many indoor and outdoor environments. It's widely used in marine-adjacent applications, industrial equipment, automotive fixtures, and architectural components. For severe salt exposure, surface treatments like anodizing or coating can extend service life, but the base alloy already offers solid resistance.

Welding is another reason 6061 stays popular. It welds well with common filler choices, though it's important to understand a tradeoff: welded zones typically lose some strength relative to T6 base metal because the heat affects the temper. Designers often compensate with joint design, local thickness, or post-weld heat treatment when required.

Chemical Composition (Typical Limits)

The exact limits depend on the governing standard, but the following table reflects widely accepted composition ranges for AA 6061. Always confirm with your supplier's certificate and the standard specified on your order.

This chemistry explains the "personality" of 6061: magnesium and silicon drive heat-treat strength, chromium helps with corrosion and grain structure control, and copper contributes to strength while remaining moderate enough to preserve good corrosion performance.

Where 3mm 6061 Sheet/Plate Shines

A 3mm 6061 sheet plate is often chosen for machine covers that must feel rigid, mounting panels that carry real loads, robot cell guarding, transport cases, electronic chassis, brackets, base plates, and laser-cut structural components. It also suits products that need a clean finish-especially when anodized-because 6061 can deliver a crisp, professional appearance when sourced in anodizing-quality surface.

From a designer's perspective, 3mm is a thickness that "behaves." It holds tapped threads better than very thin sheet, stays flatter after cutting than flimsy gauges, and still keeps weight under control.

Quick Buying Notes That Prevent Common Mistakes

If your parts will be CNC machined or must stay flat after profiling, request 6061-T651 and specify flatness expectations. If the part will be bent tightly, consider T4 or O temper, or confirm the minimum bend radius your shop can achieve in T6. If appearance matters, clarify surface class, protective film, and whether the sheet is intended for anodizing.

6061   

https://www.al-sale.com/a/3mm-thickness-aluminium-sheet-plate-6061-alloy.html