T4 T6 T651 6061 aluminum sheet plate

12/17 2025

T4 T6 T651 6061 aluminum sheet plate is a high-strength, heat-treatable alloy widely used in aerospace, transportation, mold making, and structural components. It offers an excellent balance of strength, weldability, machinability, and corrosion resistance. Available in T4, T6, and T651 tempers, 6061 plate can be tailored for bending, precision machining, or high-load structural use.

6061 aluminum is a precipitation-hardened alloy based on the Al–Mg–Si system. It is one of the most widely used structural alloys due to its:

High specific strength
Good corrosion resistance
Excellent machinability in heat-treated tempers
Reliable weldability and formability

The tempers T4, T6, and T651 represent different stages of solution heat treatment and artificial aging, allowing you to choose between better formability (T4) and maximum mechanical strength and stability (T6, T651).

Chemical Composition of 6061 Aluminum

Typical composition according to common international standards (mass fraction):

Element	Typical Range (%)
Silicon (Si)	0.40 – 0.80
Magnesium (Mg)	0.80 – 1.20
Copper (Cu)	0.15 – 0.40
Chromium (Cr)	0.04 – 0.35
Iron (Fe)	≤ 0.70
Manganese (Mn)	≤ 0.15
Zinc (Zn)	≤ 0.25
Titanium (Ti)	≤ 0.15
Others (each)	≤ 0.05
Others (total)	≤ 0.15
Aluminum (Al)	Balance

This Al–Mg–Si–Cu composition delivers a strong precipitation-hardening response while maintaining good corrosion resistance and weldability.

Temper Designations: T4 vs T6 vs T651

Temper Description

Temper	Treatment Route	Main Characteristics	Typical Use Focus
T4	Solution heat treated, naturally aged	Medium strength, excellent formability and bendability	Complex forming, deep bending
T6	Solution heat treated, artificially aged	High strength, good machinability, fair formability	Structural parts, machined components
T651	Solution heat treated, stress-relieved by stretching, artificially aged	High strength with reduced residual stress, excellent dimensional stability	Precision machining, molds, tooling

T651 is essentially T6 that has been mechanically stress-relieved, making it the preferred choice for thick plates and tight-tolerance machined parts where distortion must be minimized.

Features and Performance Advantages

Mechanical and Processing Features

Feature	Description
Strength-to-weight ratio	Significantly higher than many non-heat-treatable alloys
Machinability	Very good in T6/T651; produces clean chips and stable cutting
Weldability	Readily weldable by TIG/MIG; good post-weld strength with proper procedure
Formability	Best in T4; moderate in T6 for larger radii bends
Dimensional stability	T651 minimizes warping during heavy machining
Surface finish	Suitable for anodizing, powder coating, and mechanical polishing
Corrosion resistance	Good in most atmospheric and industrial environments

Comparison of Tempers for Common Needs

Requirement	Recommended Temper	Reason
Tight-tolerance machining	T651	Stress relief reduces distortion and residual stresses
Deep bending or complex forming	T4	Higher ductility and elongation
High static load structural use	T6 or T651	Maximum yield and tensile strength
General welded structures	T6 (locally softened at weld)	Good overall balance after welding

Mechanical Properties (Typical Values)

Typical room temperature properties for 6061 plate (approximate, for reference only; check actual MTC for guaranteed values):

Property	Unit	6061‑T4	6061‑T6	6061‑T651
Tensile strength (Rm)	MPa	180 – 240	260 – 310	260 – 310
Yield strength (Rp0.2)	MPa	110 – 160	240 – 280	240 – 280
Elongation (A50)	%	12 – 20	8 – 12	8 – 12
Brinell hardness	HBW	60 – 75	85 – 100	85 – 100
Modulus of elasticity	GPa	~69	~69	~69
Density	g/cm³	2.70	2.70	2.70
Thermal conductivity	W/m·K	~170	~170	~170
Coefficient of thermal expansion	µm/m·K	23 – 24	23 – 24	23 – 24

Standard Sizes, Thickness Range, and Tolerances

Actual availability may vary; the table below gives common commercial ranges:

Parameter	Typical Range / Note
Thickness (sheet)	0.5 – 6.0 mm
Thickness (medium plate)	6 – 25 mm
Thickness (heavy plate)	25 – 200+ mm (mainly T6/T651)
Standard widths	1000 mm, 1220 mm, 1500 mm, up to 2000 mm
Standard lengths	2000 mm, 2440 mm, 3000 mm, 4000 mm or cut-to-length
Thickness tolerance	Typically ±0.1 – ±0.5 mm, depending on gauge and standard
Flatness (plate)	Controlled especially in T651 for machining applications

For CNC machining, T651 plates are often ordered in customized cut-to-size blocks to reduce waste and machining time.

Applications of T4 T6 T651 6061 Aluminum Sheet Plate

Structural and Mechanical Components

Industry / Area	Typical 6061 Plate Uses
Aerospace & aviation	Fixtures, brackets, tooling plates, non-critical structural parts
Transportation	Truck bodies, trailers, bus floors, ship deck plates
Machinery & equipment	Machine bases, frames, jigs, robot arms, precision fixtures
Construction	Roof panels, curtain wall frames, handrails, walkways

High-Precision and Mold Uses

Segment	Application Details
Mold making	Plastic molds, blow molds, casting patterns (commonly T651)
CNC machining	Tooling plates, base plates, electronic equipment housings
Automation	Linear guide bases, positioning plates, component carriers

General Fabrication & Consumer Products

Segment	Typical Products
Sporting & leisure	Bicycle frames (parts), camera rigs, accessories
Marine & outdoor	Small boat components, gangways, platforms
Electronics & hardware	Enclosures, heat-dissipating structural parts

T4 is preferred for parts that need complex bending first and are then aged to near‑T6 strength, while T6/T651 are chosen for finished plates that will go straight into cutting and machining.

Forming, Welding, and Machining

Forming and Bending

Temper	Bending Performance	Notes
T4	Excellent	Recommended for tight radii and deep forming
T6	Moderate	Use larger bend radii, avoid sharp corners
T651	Similar to T6	Mainly used where bending is limited or minor

For critical bend operations, many users specify 6061‑T4 for forming, then perform artificial aging to reach T6-level properties after shaping.

Welding

Attribute	Description
Weldability	Good by MIG/TIG with suitable filler (e.g., 4043, 5356)
Post-weld strength	Reduced in heat-affected zone compared to base T6/T651
Corrosion behavior	Generally good; consider post-weld cleaning and coating

When high post-weld strength is essential, design allowances or post-weld heat treatment may be necessary.

Machining

Temper	Machinability Rating	Remarks
T4	Fair	Softer, may produce more built-up edge
T6	Very good	Clean cutting, good chip breaking
T651	Excellent	Best for tight tolerances and flatness-critical parts

Using T651 plates significantly reduces distortion in large pocketed or thin-wall machined components.

Corrosion Resistance and Surface Treatment

6061 aluminum exhibits good resistance to atmospheric and marine environments, especially when properly finished.

Aspect	Performance / Option
Atmospheric corrosion	Good in urban and industrial conditions
Marine splash zone	Good with appropriate paint or anodizing
Anodizing	Suitable for decorative and hard anodizing
Painting & coating	Accepts powder coating, liquid painting, and conversion coatings

For outdoor and marine applications, a combination of 6061 plate plus anodizing or coating extends service life and maintains appearance.

How to Select the Right 6061 Temper

Design Priority	Suggested Choice	Reason
Maximum strength, general use	6061‑T6	Established standard for strong structural parts
High strength + minimal distortion	6061‑T651	Stress relief for machining-intensive components
Tight bends / deep drawing	6061‑T4	Higher ductility and formability
Welded structures with machining	6061‑T6 / T651	Good balance of weldability and post-weld machining