6061-T651 vs T6 vs T6511: What’s the Difference?

 

When engineers and procurement specialists search for aluminum 6061 materials, they often encounter three confusing terms: 6061-T6, 6061-T651, and 6061-T6511. While they may look similar on paper, choosing the wrong one for CNC machining projects can lead to dimensional instability, reduced strength, or unnecessary machining costs.

 

The frustration comes from technical jargon—heat treatments, stress relief processes, and mechanical property variations—that are rarely explained clearly for real-world manufacturing needs.

The good news is that with the right knowledge, you can choose the correct 6061 alloy variant, improve 6061 CNC machined parts quality, and save on production costs. This guide breaks down each type, their properties, and their best applications in CNC machining services.

 

• Tip: Choosing the wrong aluminum 6061 variant can increase post-machining warping risk—especially for long or thin parts.

 

6061-T6 is heat-treated aluminum without stress relief, 6061-T651 is stress-relieved T6 for improved stability, and 6061-T6511 is stress-relieved with controlled straightness for extruded shapes. Choosing depends on dimensional tolerance needs, part size, and machining requirements.

 

Understanding the difference between 6061-T6, T651, and T6511 is not just a matter of technical curiosity—it’s a cost and quality decision. The right choice affects machinability, strength, and final tolerance stability.

 

In the sections below, we’ll compare chemical composition, mechanical properties, and physical performance to help engineers, designers, and buyers select the right alloy for their aluminum CNC machined parts. For deeper insights on aluminum alloys, you can also explore related guides on our website about 7075-T6 vs. 6061-T6 and MIC-6 cast aluminum plates, which offer different strengths for CNC machining projects.

 

 

 

 

6061-T6, 6061-T651, and 6061-T6511 Aluminum Analysis

 

 

 

 

What is 6061-T6?

 

6061-T6 is a heat-treated aluminum alloy from the aluminum 6061 family, known for its balanced strength, corrosion resistance, and machinability. The “T6” designation means the material is solution heat-treated and artificially aged to achieve maximum strength.

 

However, it has not undergone stress-relief stretching, which means residual stresses from heat treatment can remain in the material. In CNC machining, these stresses can cause dimensional changes after milling, particularly for large, thin, or asymmetrical parts.

 

This variant is commonly used for structural frames, automotive parts, and aerospace components where high strength-to-weight ratio is essential but extreme dimensional stability is not critical.

 

• Note: If you machine a long plate from 6061-T6, warping risk is higher than with T651 or T6511—factor in extra stock allowance.

 

 

What is 6061-T651?

 

6061-T651 is essentially 6061-T6 that has undergone stress relief by stretching. The “51” suffix indicates that after heat treatment, the aluminum is stretched to relieve internal stresses before being machined.

 

This makes it a preferred choice in CNC machining factories for projects requiring tight tolerances and minimal post-machining distortion. It is particularly beneficial for precision components, aerospace fittings, and large aluminum CNC machined parts where dimensional accuracy is critical.

 

• Tip: For flatness-critical applications, T651 offers better dimensional stability compared to T6, reducing costly rework.

 

 

What is 6061-T6511?

 

6061-T6511 is a variant of T651, primarily applied to extruded shapes such as bars, rods, and profiles. After heat treatment and stress relief, it undergoes a controlled straightening process to meet precise dimensional tolerances for extrusions.

 

This makes T6511 ideal for applications like automotive chassis, machine tool components, and structural frames where straightness and stability are essential, but the parts originate from extruded stock.

 

• Note: If your project involves extruded aluminum CNC machined parts, T6511 will generally maintain better straightness than T6 or uncorrected extrusions.

 

 

 

 

6061-T651 vs. 6061-T6 vs. 6061-T6511: What’s the Difference?

 

 

At first glance, 6061-T6, 6061-T651, and 6061-T6511 aluminum may appear identical—they share the same base alloy, aluminum 6061, and nearly identical chemical composition. However, their mechanical performance, dimensional stability, and suitability for CNC machining can differ significantly due to variations in post-heat-treatment processes.

 

The main distinction lies in stress relief and straightness control. 6061-T6 is the baseline, strong but with residual stresses; 6061-T651 adds stretching to remove those stresses; and 6061-T6511 combines stretching with precise straightening for extrusions. Choosing incorrectly can cause machining distortion, assembly issues, and unexpected project delays.

 

For customers sourcing aluminum CNC machined parts through CNC machining services, understanding these differences ensures parts meet tolerance requirements without costly rework. This section will start by comparing their chemical composition, which forms the foundation of their mechanical and physical behavior.

 

• Tip: Even though their chemical composition is the same, differences in heat treatment and stress relief can dramatically affect CNC machining performance.

 

 

 

 

Chemical Composition

 

Aluminum 6061—regardless of whether it is T6, T651, or T6511—shares the same nominal chemical makeup. The alloy is primarily aluminum, with magnesium and silicon as the main alloying elements, plus trace amounts of copper, iron, and other elements to fine-tune performance.

 

Typical chemical composition for 6061 series alloys is:

• Aluminum (Al): 95.8–98.6% — Provides lightweight structure and corrosion resistance.
• Magnesium (Mg): 0.8–1.2% — Improves strength and corrosion resistance.
• Silicon (Si): 0.4–0.8% — Combines with magnesium to form Mg₂Si, increasing hardness.
• Copper (Cu): 0.15–0.40% — Enhances strength but can slightly reduce corrosion resistance.
• Chromium (Cr): 0.04–0.35% — Improves toughness and resistance to stress corrosion cracking.
• Iron (Fe): ≤ 0.70% — Generally considered an impurity but may affect machinability.
• Zinc (Zn): ≤ 0.25% — Minimal effect in 6061 but may influence anodizing color.
• Titanium (Ti): ≤ 0.15% — Helps refine grain structure for improved mechanical properties.

While all three tempers—6061-T6, 6061-T651, and 6061-T6511—share this composition, their different tempering and stress-relief treatments result in distinct mechanical property profiles, which we will examine next.

 

• Note: Since chemical composition is identical, choosing between T6, T651, and T6511 is about process differences rather than alloy chemistry. Your decision should be based on machining requirements and tolerance demands, not just composition.

 

 

Chemical Composition

 

While 6061-T6, 6061-T651, and 6061-T6511 share the same aluminum 6061 base alloy, their mechanical properties differ because of tempering and stress-relief processes, not chemical makeup.

 

Here’s the typical chemical composition of aluminum 6061:

 

 

 

• Note: Regardless of whether you choose 6061-T6, 6061-T651, or 6061-T6511, this chemical composition remains the same. The key differences come from heat treatment and stress-relief methods, which directly impact machining behavior and dimensional stability.

 

 

Mechanical Properties

 

Even though 6061-T6, 6061-T651, and 6061-T6511 have identical chemical compositions, their mechanical properties vary because of stress relief and straightening processes.

 

These differences directly affect CNC machining performance, dimensional stability, and final part quality. For example, the tensile strength of 6061-T6 is similar to T651, but the stress relief in T651 reduces the likelihood of distortion after machining. T6511 has comparable strength to T651 but with improved straightness for extrusions, making it ideal for long aluminum CNC machined parts such as structural frames and machine components.

 

Choosing the wrong variant can mean extra rework, higher costs, and longer lead times—especially for parts requiring tight tolerances from CNC machining factories.

 

• Tip: For thin-walled or long parts, prioritize T651 or T6511 over T6 to minimize warping.

 

 

Mechanical Property Comparison Table

 

 

 

 

• Note: Although the raw strength values appear identical, T651 and T6511’s real-world performance in CNC machining is often superior due to lower residual stress, which results in better dimensional accuracy.

 

 

Physical Properties

 

 

While mechanical properties define how an alloy handles stress and load, physical properties dictate its performance in thermal, electrical, and environmental conditions. For 6061-T6, 6061-T651, and 6061-T6511, these physical characteristics are largely identical, since they share the same aluminum 6061 chemical composition.

 

However, understanding these parameters is crucial for CNC machining services—especially when parts will be exposed to heat, electrical currents, corrosive environments, or welding operations. A designer choosing material for aluminum CNC machined parts must account for these properties to ensure long-term reliability.

 

• Tip: For high-heat or marine environments, pairing aluminum 6061 with protective anodizing can significantly extend component lifespan.

 

 

 

Thermal Conductivity (W/m·K)

 

All three temper variants offer high thermal conductivity, typically around 167 W/m·K, making them suitable for heat sinks, engine components, and electronic housings.

 

 

Electrical Conductivity (%)

 

With an electrical conductivity of about 43% IACS, aluminum 6061 conducts electricity well enough for bus bars, enclosures, and electronic frames, though not as well as pure aluminum.

 

 

Melting Range (°C)

 

The alloy melts between 582–652°C, providing adequate thermal tolerance for most manufacturing processes, but care must be taken in high-temperature operations like forging.

 

 

Density (g/cm³)

 

At around 2.70 g/cm³, aluminum 6061 is lightweight, making it ideal for aerospace, automotive, and structural CNC machined parts.

 

 

Coefficient of Thermal Expansion (μm/m·°C)

 

The expansion rate is 23.6 μm/m·°C, meaning that thermal changes can slightly alter dimensions—important when designing precision assemblies.

 

 

Melting Point (°C)

 

The solidus point is around 582°C, and the liquidus at 652°C, defining its processing temperature limits.

 

 

Corrosion Resistance

 

Aluminum 6061 has excellent corrosion resistance, especially in atmospheric and marine environments, making it popular for outdoor CNC machined components.

 

 

Wear Resistance

 

While not as hard as some alloys, it offers moderate wear resistance, which can be enhanced with surface treatments like anodizing.

 

 

Oxidation Resistance

 

Forms a natural oxide layer that resists further oxidation, ideal for parts without heavy chemical exposure.

 

 

Welding

 

Highly weldable using TIG or MIG methods, though mechanical strength in the weld zone may decrease without post-weld heat treatment.

 

 

Magnetic Properties

 

Non-magnetic, suitable for sensitive electronic equipment housings where magnetism could interfere with operation.

 

 

Formability

 

Good formability in the T6 condition; excellent in the annealed state before final heat treatment.

 

 

Machinability (Annealing)

 

In the T6 and T651 conditions, machinability is rated as good, producing clean finishes for aluminum CNC machined parts.

 

 

Physical Properties Comparison Table

 

 

 

 

• Note: Physical property similarities mean that your choice between 6061-T6, 6061-T651, and 6061-T6511 should focus on stress relief, stability, and machining requirements, not thermal or corrosion performance.

 

 

Strength

 

When it comes to structural performance, 6061-T6, 6061-T651, and 6061-T6511 share similar ultimate tensile and yield strengths, since their base alloy and heat treatment levels are the same. The typical tensile strength is about 310 MPa, and the yield strength is around 276 MPa for all three.

 

However, while raw strength is nearly identical, T651 and T6511 deliver more consistent strength across the entire workpiece due to stress-relief processes. This consistency becomes critical in CNC machining services, where removing material can cause non-stress-relieved plates or bars to distort, weakening certain sections.

 

For heavy-duty load-bearing aluminum CNC machined parts—such as aerospace brackets, automotive suspension components, and industrial machine frames—T651 or T6511 often outperform T6 in maintaining long-term shape and load capacity.

 

• Tip: In high-precision applications, dimensional stability is often more important than maximum tensile strength. Always factor in machining distortion risks.

 

 

Dimensional Stability Comparison

 

Dimensional stability refers to a material’s ability to maintain its exact measurements after machining, temperature changes, or long-term use.

• 6061-T6: Strong but more prone to post-machining warping because residual stresses from heat treatment remain.
• 6061-T651: Stress-relieved by stretching, which releases most residual stresses—resulting in improved flatness and reduced distortion.
• 6061-T6511: Includes the same stress relief as T651 but with controlled straightening for extruded profiles, making it the most dimensionally stable choice for long, narrow shapes like rods, beams, and frame elements.

For CNC machining factories producing tight-tolerance aerospace panels, precision jigs, or long mechanical arms, choosing T651 or T6511 minimizes rework time and scrap rates.

 

• Note: If your part will be machined from a thick plate or long extrusion, the right temper choice can save hours in final adjustments.

 

 

 

 

 

Vibration Damping

 

Aluminum 6061 is not known for exceptional vibration damping compared to materials like cast iron, but temper choice can still influence performance in sensitive applications.

 

Because 6061-T651 and 6061-T6511 undergo stress relief, they tend to exhibit slightly improved vibration stability after machining, especially in parts with thin walls or extended spans. This stability benefits precision measuring equipment frames, CNC machine tooling components, and aerospace sensor housings where vibration can reduce accuracy or service life.

 

While damping properties are primarily governed by the base aluminum alloy’s modulus of elasticity (68.9 GPa), reducing internal stress also helps maintain tight fits and alignment under vibratory loads.

 

• Tip: For applications with continuous vibration—such as machine tool bases or vehicle suspension arms—pair aluminum 6061 with a damping surface treatment or composite structure for best results.

 

 

 

 

Heat Treatment of 6061-T6, 6061-T651, and 6061-T6511

 

 

Heat treatment plays a crucial role in defining the performance characteristics of 6061 aluminum alloys. While 6061-T6, 6061-T651, and 6061-T6511 share the same chemical composition, they undergo slightly different processing methods, resulting in variations in residual stress, dimensional stability, and machinability. Understanding these distinctions helps engineers, designers, and procurement teams choose the optimal temper for CNC machining applications.

 

 

 

 

 

6061-T6 Alloy

 

The 6061-T6 temper is achieved by solution heat treating the alloy, followed by artificial aging. The solution heat treatment dissolves soluble phases into a solid solution, while the artificial aging process precipitates fine Mg₂Si particles to increase strength. This results in high tensile strength, good corrosion resistance, and balanced machinability.

 

However, T6 retains residual stresses from the quenching process, which can cause warping during machining—an important consideration for high-precision CNC parts.

 

Key Heat Treatment Steps:

• Solution heat treat at ~530°C.
• Water quench to room temperature.
• Artificially age at ~160–180°C for 8 hours.

 

 

6061-T651 Alloy

 

6061-T651 is essentially the T6 temper with an additional stress-relief stretching step. After solution heat treatment and artificial aging, the alloy is stretched by approximately 1.5–3% to reduce internal stresses. This extra process minimizes the risk of distortion during machining, making T651 the preferred choice for high-precision and large CNC aluminum parts.

 

While mechanical strength is nearly identical to T6, the improved dimensional stability makes T651 more reliable for critical aerospace, defense, and mold-making applications.

 

Key Heat Treatment Steps:

• Same T6 process (solution heat treat, quench, artificial aging).
• Stretching by 1.5–3% to relieve stress.

 

 

6061-T6511 Alloy

 

6061-T6511 follows the same heat treatment sequence as T651 but applies to extruded products rather than plate or rolled material. The “11” designation indicates that the product has been stress-relieved by stretching after solution heat treatment and artificially aged, but in the form of bars, rods, or shapes.

 

For CNC machining, T6511 is often used when long extrusions are needed for structural components, as it combines good machinability with improved stability over T6.

 

Key Heat Treatment Steps:

• Solution heat treat at ~530°C.
• Water quench.
• Artificial aging at ~160–180°C.
• Stretching for stress relief (applied to extrusions).

 

 

Heat Treatment Comparison for 6061-T6, 6061-T651, and 6061-T6511

 

 

 

 

 

 

 

 

Advantages and Disadvantages of 6061-T6, 6061-T651, and 6061-T6511

 

 

When selecting aluminum for CNC machining parts, 6061 in its different tempers — T6, T651, and T6511 — offers a balance of strength, machinability, and corrosion resistance. Each variant undergoes specific heat treatment and stress-relieving processes, resulting in differences in mechanical performance, stability, and application suitability. Understanding their advantages and disadvantages helps engineers, procurement specialists, and CNC machining factories choose the right material for each project.

 

 

Advantages of 6061-T6, 6061-T651, and 6061-T6511

 

While all three share the same chemical composition, their tempering process influences performance. Here’s a breakdown of their benefits.

 

 

 

6061-T6 Alloy

• High strength-to-weight ratio suitable for aerospace and automotive parts
• Excellent corrosion resistance in marine and industrial environments
• Good machinability, making it a common choice for CNC machining services
• Widely available in plate, bar, and sheet form

6061-T651 Alloy

• Improved dimensional stability due to stress relieving via stretching
• Reduced warping during CNC milling or heavy machining operations
• Maintains the same strength as T6 while offering better tolerance control
• Ideal for precision components and tooling plates

6061-T6511 Alloy

• Best dimensional control for long extrusions due to straightening process
• Retains the strength and corrosion resistance of T6 and T651
• Suitable for structural profiles, marine hardware, and long aerospace components
• Lower distortion risk during high-precision CNC machining

 

 

Disadvantages of 6061-T6, 6061-T651, and 6061-T6511

 

Despite their popularity, each temper has certain drawbacks that may impact cost, production efficiency, or performance in specific applications.

 

6061-T6 Alloy

• More prone to warping during heavy machining due to lack of stress relief
• Not as dimensionally stable as T651 or T6511
• Slightly less suitable for very tight tolerance CNC parts

6061-T651 Alloy

• Slightly higher cost than T6 due to additional stress-relieving process
• Limited to certain forms (commonly plates and large bars)
• May not be necessary for parts where warping is not a concern

6061-T6511 Alloy

• Highest cost among the three due to both stress relief and straightening
• Primarily available in extrusion form, limiting shape options
• May require longer lead times from CNC machining factories due to specialized production

 

Here’s the comparison table for the advantages and disadvantages of 6061-T6, 6061-T651, and 6061-T6511:

 

 

 

 

 

 

 

 

6061-T6 and T6511 Interchangeability

 

Here’s a clear breakdown of 6061-T6 and 6061-T6511 interchangeability in a CNC machining context:

 

 

 

 

Summary:

• Yes, they can be interchangeable if your design uses extruded profiles and the small strength difference is acceptable.
• No, they aren’t interchangeable for plate material — T6511 is only available as extrusions.
• For tight-tolerance CNC parts, T6511 is often the better choice due to its stress-relieved nature.

 

 

 

 

 

6061 T6, T651, and T6511: Applications and Uses

 

 

Alloy 6061 is one of the most widely used aluminum alloys in CNC machining services due to its excellent strength-to-weight ratio, corrosion resistance, and machinability. Within this family, the 6061-T6, 6061-T651, and 6061-T6511 tempers each have unique processing characteristics, making them suitable for specific industries and applications. Understanding where each alloy excels helps manufacturers, engineers, and procurement teams choose the right material for their CNC machining projects.

 

 

 

 

Applications of 6061-T6 Alloy

 

The 6061-T6 temper is heat-treated and artificially aged, offering high strength and good corrosion resistance, making it versatile for a wide range of industries. Common applications include:

• Aircraft Components – Used for structural parts such as wings, fuselage frames, and support brackets where strength and light weight are essential.
• Automotive Components – Ideal for chassis parts, engine blocks, and performance car modifications due to its durability.
• Sporting Equipment – Applied in high-performance sports gear, such as archery bows, baseball bats, and outdoor adventure tools.
• Door and Window Fixtures – Provides both aesthetic appeal and weather resistance in architectural designs.
• Gardening Tools – Offers corrosion resistance for durable and lightweight garden equipment.
• Marine/Ship Parts – Used for boat frames, decks, and hardware due to resistance to saltwater corrosion.
• Pipes and Tubing – Ensures reliability in fluid transportation systems.
• Bicycle Frames – Lightweight yet rigid, perfect for competitive cycling.
• Frames and Structures – Utilized in industrial frameworks where stability and weight efficiency matter.
• Industrial Equipment Frames – Supports machinery and manufacturing setups requiring rigidity.
• Electronic Equipment Enclosures – Protects sensitive electronics from mechanical and environmental damage.

 

Applications of 6061-T651 Alloy

 

The 6061-T651 temper is similar to T6 but has undergone stress-relieving by stretching, reducing internal stresses and improving dimensional stability—ideal for precision CNC machining. Common applications include:

• Machinery Parts – Excellent for components requiring tight tolerances and minimal warping during production.
• Aircraft Components – Suitable for load-bearing structures where stability and accuracy are critical.
• Automotive Parts – Used for engine mounts, suspension parts, and custom racing parts.
• Bicycles and Bicycle Frames – Delivers improved alignment stability in performance frames.
• Structural Frames – Supports heavy-duty construction and industrial frameworks.
• Fittings and Pipes – Provides consistent dimensional integrity for industrial piping systems.
• Marine Applications – Perfect for precision ship components and offshore equipment.
• Consumer Products – Applied in high-quality goods such as laptop chassis, camera parts, and outdoor gear.

 

Applications of 6061-T6511 Alloy

 

The 6061-T6511 temper has the same mechanical properties as T651 but is typically supplied as extruded products and is stress-relieved by stretching after solution heat treatment. This makes it particularly suited for elongated and complex shapes. Applications include:

• Automotive Body Panels – Used in vehicle bodywork for strength and weight efficiency.
• Frames and Chassis – Suitable for transportation structures where precision and load handling are important.
• Electronic Enclosures – Protects internal components while offering a clean, finished look.
• Machinery/Equipment Enclosures – Shields delicate equipment from environmental and mechanical impact.
• Machine Tools and Parts – Provides durability and accuracy in tooling and mechanical assemblies.
• Signages/Displays – Offers excellent surface finish for commercial and architectural signage.
• Medical Equipment – Suitable for lightweight and corrosion-resistant medical devices.
• Transportation Structures – Used in rail, bus, and aerospace frameworks.
• Enclosures for Severe Weather Conditions – Performs well in outdoor and harsh climate applications.

 

 

Here’s a clean, well-structured table comparing the applications and uses of 6061 T6, 6061 T651, and 6061 T6511:

 

 

 

 

    

 

 

6061 T6, T651, and T6511: Cost and Pricing

 

 

Cost and Pricing Overview

 

The cost of 6061 aluminum alloys—whether T6, T651, or T6511—depends on several factors, including raw material prices, dimensions, machining complexity, order volume, and any special surface treatments. In general, 6061-T6 is the most widely available and therefore often the most competitively priced, while T651 and T6511 may cost slightly more due to additional processing and dimensional stability requirements.

 

 

6061-T6 Pricing

 

As the most common heat-treated variant of 6061 aluminum, T6 is generally the most affordable choice. Its price per kilogram or pound is typically 5–10% lower than T651 or T6511. Customers often select T6 for large-scale projects such as aircraft frames, automotive parts, or marine structures where strength and corrosion resistance are needed without strict flatness tolerances. Bulk orders can lead to further discounts, especially from CNC machining factories with direct supplier relationships.

 

 

6061-T651 Pricing

 

T651 undergoes stress-relieving after heat treatment, which ensures superior flatness and dimensional stability—especially important for precision CNC machined parts. This extra processing generally adds a 5–15% price premium over T6. Buyers in aerospace, defense, and high-precision manufacturing often consider the added cost justified by the reduced risk of warping during machining, which ultimately saves rework and material waste.

 

 

6061-T6511 Pricing

 

T6511 is similar to T651 but applies specifically to extruded profiles. Its pricing depends not only on size and thickness but also on the complexity of the extrusion shape. Intricate profiles with tight tolerances tend to be more expensive. T6511 often costs slightly more than T651 when custom tooling is required, but for standard extrusion shapes, pricing is comparable. Many CNC machining factories source T6511 for long structural parts, frames, and transport applications where both machinability and weather resistance are critical.

 

 

Additional Cost Factors

 

Beyond alloy type, costs can be affected by:

• Order Quantity – Larger batches reduce unit pricing.
• Material Dimensions – Thicker plates or longer extrusions carry higher base prices.
• Surface Finish – Anodizing, powder coating, or polishing add to total cost.
• Market Conditions – Fluctuations in aluminum commodity prices can cause short-term price changes.

 

Here’s a clear comparison table for 6061 T6, T651, and T6511 Cost and Pricing:

 

 

 

 

 

 

 

6061 T6, T651, and T6511: Different Stock Shapes

 

Here’s a comparison table for 6061 T6, T651, and T6511: Different Stock Shapes:

 

 

 

 

 

 

 

How to Choose Between Aluminum 6061-T651, Aluminum 6061-T6, and Aluminum 6061-T6511?

 

 

Aluminum 6061 is one of the most versatile alloys, but its performance depends heavily on the temper — T6, T651, and T6511. Each has distinct manufacturing processes and mechanical properties, making them suitable for different applications. Understanding when to use each variant helps engineers, designers, and procurement managers make cost-effective and performance-driven choices.

 

 

When to Use Aluminum 6061-T651?

 

Aluminum 6061-T651 is stress-relieved by stretching after heat treatment, which reduces internal stresses and minimizes distortion during machining. It is the preferred choice for thick plates and precision-machined parts where stability and accuracy are critical. This makes it ideal for aerospace structural components, precision tooling plates, and heavy-duty machinery frames. If your project requires minimal warping during machining, T651 is often the go-to option.

 

 

When to Use Aluminum 6061-T6?

 

Aluminum 6061-T6 is the standard solution heat-treated and artificially aged version without stress relief stretching. It offers an excellent balance of strength, corrosion resistance, and machinability, making it a cost-effective option for general-purpose applications such as automotive parts, bicycle frames, sporting goods, and marine fittings. Choose T6 when you need versatility, availability in various shapes, and moderate strength at a lower cost compared to stress-relieved tempers.

 

 

When to Use Aluminum 6061-T6511?

 

Aluminum 6061-T6511 is similar to T651 but produced in extruded forms like bars, rods, tubes, and custom profiles. It is straightened after stretching, offering high dimensional stability for long-length extrusions. This makes it ideal for structural frames, machine tool components, transportation parts, and architectural extrusions. If your design involves long, precise, and straight aluminum profiles, T6511 is the best option.

 

 

Here’s the comparison table for Aluminum 6061-T6, 6061-T651, and 6061-T6511:

 

 

 

 

 

 

 

 

VMT: Providing Aluminum CNC Machining Parts Services

 

 

When it comes to precision, durability, and efficiency in aluminum parts manufacturing, VMT CNC Machining Services stands out as a trusted partner for global clients. Specializing in 6061-T6, 6061-T651, and 6061-T6511 aluminum alloys, VMT delivers high-quality aluminum CNC machining parts that meet strict industrial standards and customer-specific requirements.

 

Our advanced CNC machining factories are equipped with multi-axis machining centers, enabling us to handle everything from small, intricate components to large structural frames. Each aluminum part is produced with tight tolerances, excellent surface finishes, and consistent quality, ensuring optimal performance in applications such as aerospace, automotive, marine, and industrial machinery.

 

Whether you require custom aluminum prototypes or large-volume production runs, VMT offers end-to-end CNC machining services — from material selection and engineering design support to precision manufacturing, finishing, and quality inspection. Our expertise with 6061 aluminum alloys ensures your parts maintain superior strength, corrosion resistance, and machinability, while also offering cost-effective production.

 

Choosing VMT means choosing reliability, precision, and efficiency. We are committed to delivering aluminum CNC machining parts that not only meet but exceed your expectations.

 

 

 

 

 

Conclusion

 

 

Selecting the right aluminum alloy temper — whether 6061-T6, 6061-T651, or 6061-T6511 — is critical to achieving optimal performance, cost efficiency, and durability in CNC machined parts. Each offers unique advantages: T6 for balanced strength and machinability, T651 for improved stress relief and dimensional stability, and T6511 for extruded profiles with enhanced straightness.

By understanding these differences, engineers, designers, and procurement specialists can make informed decisions that align with their project’s technical and budgetary requirements.

 

At VMT CNC Machining Services, we combine material expertise with precision manufacturing to deliver high-quality aluminum CNC machining parts that meet the demands of industries from aerospace to automotive. Our advanced CNC machining factories ensure every component is crafted with tight tolerances, excellent surface finishes, and consistent quality.

 

When your project demands precision, reliability, and performance, VMT is your trusted partner for 6061 aluminum CNC machined parts — from concept to final delivery.

 

 

 

 

 

 

FAQs

 

 

1. What is the difference between 6061-T651 and 6061-T6511?

 

Both are heat-treated, stress-relieved versions of 6061 aluminum. The difference lies in manufacturing: T651 is produced from plate, while T6511 comes from extruded profiles and is additionally straightened after stretching for better dimensional accuracy.

 

 

2. What is the difference between T6 and T651?

 

T6 is solution heat-treated and artificially aged to achieve maximum strength. T651 undergoes the same process but is stress-relieved by stretching to reduce internal stresses, making it less prone to warping during machining.

 

 

3. What is the difference between 6061-T651 and 7075-T651?

 

6061-T651 offers excellent corrosion resistance and weldability, while 7075-T651 provides significantly higher strength but lower corrosion resistance. The choice depends on whether strength or environmental durability is more important.

 

 

4. What is the difference between T6 and T61 heat treatments?

 

T6 involves full artificial aging after solution heat treatment, whereas T61 is a variation with a slightly different aging process, resulting in slightly different mechanical properties.

 

 

5. What is 6061-T651 aluminum used for?

 

It is widely used for precision CNC machined parts in aerospace, automotive, marine, and structural applications requiring high strength, stability, and corrosion resistance.

 

 

6. Is 6061-T6511 machinable?

 

Yes. 6061-T6511 aluminum is highly machinable, especially for long extruded profiles where dimensional stability and straightness are critical.

 

 

7. What is the equivalent material for 6061-T6?

 

International equivalents include AlMg1SiCu in Europe and A96061 in UNS designation. Properties can vary slightly depending on manufacturing standards.

 

 

8. Is 6061-T6511 heat treated?

 

Yes. 6061-T6511 undergoes solution heat treatment, artificial aging, and stress-relieving by stretching.

 

 

9. What does T6 stand for in aluminum?

 

It means the alloy has been solution heat-treated and artificially aged for maximum strength.

 

 

10. Is 6061-T6511 weldable?

 

Yes, it has excellent weldability using MIG or TIG welding, although post-weld heat treatment may be necessary to restore strength in the heat-affected zone.

 

 

11. Can 6061-T651 be bent?

 

Yes, but it requires a larger bend radius compared to softer tempers to prevent cracking.

 

 

12. Is 6061-T6 expensive?

 

It is cost-effective compared to aerospace-grade aluminum like 7075, offering a strong balance between performance and price.

 

 

13. Is T651 better than T6?

 

Not necessarily “better,” but T651 is preferred when machining large parts due to reduced risk of distortion.

 

 

14. Is 6061-T651 aluminum strong?

 

Yes, with a tensile strength around 45,000 psi, it offers excellent structural performance for a wide range of applications.

 

 

15. Is 6061-T6 forged or cast?

 

It is typically produced as a wrought alloy, meaning it is rolled or extruded rather than cast.

 

 

16. What is the strongest aluminum alloy?

 

7075-T6 is among the strongest, with significantly higher strength than 6061, but lower corrosion resistance.

 

 

17. Is 6061-T6 the same as T6511?

 

No. While they share the same base alloy, T6511 is extruded and stress-relieved, whereas T6 refers to the heat treatment only, without specifying the manufacturing process.