What are the difference between 6061 and 6063 Aluminum?

Table of Contents

I. Introduction

The 6061 and 6062 aluminum alloys are almost similar, coming from the 6000 aluminum series. These alloys show almost the same physical and mechanical properties, although there is a subtle difference. Since aluminum is one of the most widely used metals in the manufacturing industries, understanding the difference between the 6061 and 6063 aluminum alloys comes in handy to engineers and product designers. This post will look at the differences between these two alloys to help you make an informed decision when selecting aluminum alloy for your application.

6061 and 6063 Aluminum

B. Significance of understanding the differences

Understanding the differences of the 6061 and 6063 aluminum alloys is important because of their wide application in various industries. While these alloys share most of the characteristics, the subtle difference could greatly impact the end product depending on the alloy you use. Some of the differences are exhibited in strength. 6063 aluminum has a higher tensile strength than the 6061. While both alloys have good weldability and machining properties, 6063 aluminum supersedes the 6061 weldability and extrusion. 6061 aluminum beats the 6063 when it comes to versatility and therefore suitable for application in a wide range of industries.

Both 6061 and 6063 aluminum are both wrought alloys and extrusions, but the primary distinction lies in their applications. As such, it’s important to know that the differences between 6061 and 6063 aluminum will impact cost, strength, corrosion resistance, impact strength, machinability and temper. Furthermore, their alloy contents vary – these could include:

  • *6AL-4V (Aluminum-4.5% Vanadium) 6061 and 6063 aluminum is commonly used in extrusions, sheets, plates, bars and profiles.
  • *6AL-2V (Aluminum-3.0% Vanadium) 6061 and 6063 aluminum is widely used in aerospace industries for aircraft parts and components that need exceptional strength, corrosion resistance, and high strength-to-weight ratios.
  • Aeronautically speaking, these two alloys have no discernible difference due to their aluminum content.
  • * 6AL-4V (Aluminum-4.5% Vanadium) 6061 and 6063 aluminum has high tensile strength, good impact strength, and superior fatigue resistance when exposed to extreme temperatures. Conversely, 6AL-2V (Aluminum-3.0% Vanadium) exhibits better wear resistance than its aluminum counterpart 6AL-4V alloy at higher temperatures.

II. Composition and Properties

A. Chemical Composition

These alloys are made up of the same elements since they come from the 6000 series of Aluminum. The main difference is that 6061 aluminum contains slightly more iron than the 6063 counterpart. Other elements included in these aluminum alloys include silicon, copper and chromium where aluminum 6061 has more of each element than aluminum 6063. Other elements can be present in these alloys such as manganese and titanium, but these elements vary depending on the type of alloy. Aluminum alloys are created from bauxite (Al2O3). Due to its high aluminum content, most of the impurities are removed before processing into sheet or ingot form. Copper acts as an alloying element in aluminum, determining its mechanical and physical characteristics such as tensile strength, hardness, electrical conductivity and corrosion resistance.

B. Mechanical Properties

Aluminum 6061 and 6063 have similar mechanical properties, though their strengths differ slightly. Aluminum 6063 (215 MPa) boasts higher tensile strength than aluminum 6061 (186 MPa); making it more suitable for applications where maximum stress is expected, such as aerospace or marine applications. Aluminum 6061 has also a higher yield strength compared to aluminum 6063. This means that aluminum 6061 can withstand higher levels of stress without deformation. Aluminum 6061 is harder than 6063 according to the Brinell hardness scale. It also has better machinability compared to the 6063 aluminum. In general, 6061 aluminum has more strength and ductility than 6063. That is why it is preferred in applications where the conditions are hasher and there is more stress.

III. Heat Treatment and Temper Designations

A. Heat Treatment Processes

Aluminum 6061 and 6063 are both anodized to add a protective layer and enhance certain qualities to the product. Anodizing alters aluminum by depositing a thin layer of hard nickel or chromium oxide on its surface. Anodization of these alloys occurs through three distinct steps, normalization, tempering and hardening. Normalization involves thermal treatment at 400 C for 10 minutes to convert both aluminum alloys from having no iron content to having 10% iron content. Aluminum 6061 contains 10% iron which becomes saturated into the metal, increasing its hardness and ductility value. This process also makes the alloy resistant to oxidation – essential for applications using aluminum in corrosive environments. The alloy will become more resistant to wet and dry chloride environments. Another alternative for heat treatment is hardening. Hardening heats aluminum 6061 and 6063 from 2-3% iron to 10% iron content. Iron, nitrogen and silicon content all play a role in alloy hardenability. To do this, metal alloys must be heated between 900 to 1000 C for around 30 minutes at high temperatures. Not only does this increase yield strength of silicon-rich aluminum by 30% but it also improves wear resistance – making it suitable for environments such as marine or aeronautical uses.

Heat Treatment Processes of 6061 Aluminum

Heat treatment time can vary based on the requirements when fabricating expansion joints for a given application. Normal or short heating time processes can be employed depending on the requirements. The process is then finished by heating aluminum above its annealing temperature range and then allowing it to cool slowly. The amount of heat treatment or annealing that takes place will determine the final mechanical properties. Long annealing or normal processes offer superior performance when marine environments are concerned. Conversely, short processes provide superior results at slightly higher cost due to less conductivity for higher temperature applications such as airport tarmacs.

Heat Treatment Processes of 6063 Aluminum

6063 aluminum alloys typically undergo quenching and tempering, where components made from it are quenched at 1300 degrees F then raised to 1550 degrees F for tempering. As demonstrated by commercial tests below, heat treatment had an impact on tensile strength, yield strength and hardness; all three values decreased after annealing but returned to similar values after tempering between 700-1400 degrees Fahrenheit.

B. Temper Designations

Tempering is a heat treatment at temperatures greater than 800 C for 15 minutes, designed to remove excess iron and sulfur from an alloy by heating and cooling it 10 times between 180 and 450 degrees C. While this removes some impurities, as alloys are not 100% pure, tempering has less of an impact than normalization does. Tempering also decreases hydrogen content in aluminum 6061 while raising iron content by 2-3%; further increasing strength while decreasing ductility.

Aluminum 6061 and 6063 can be heat treated using various methods such as precipitation hardening or carburizing. Precipitation hardening is a process that changes alloys from having zero iron content to having 2% iron content, which requires heating the aluminum alloy at 1200 degrees for about 90 minutes. This process increases the strength of an alloy but reduces its ductility and toughness, making it less suitable for applications in aerospace than carburizing which has minimal effects on these alloys. Carburizing aluminum 6061 and 6063 alloys from 1-2% iron content to 5-6% improves their properties, making them suitable for marine and aeronautical uses.

IV. Formability and Machinability

A. Formability

Formability is a property that describes how easily metal can be permanently deformed. Aluminum 6061 and 6063 both possess similar formability properties, though 6063 boasts higher tensile strength and yield strength while providing less ductility. As both aluminum alloys were cast using the same high-pressure die cast method, forming should produce similar results for both alloys. Machining 6061 aluminum requires similar tools as using 6063 aluminum; only material hardness and the type of cutting tool used will determine its machinability.

B. Machinability

Machinability is a property that describes how easily metals can be cut and removed from their final shape through mechanical methods such as rapid prototypingCNC machiningmold manufacturing, etc. Aluminum 6061 has greater plasticity compared to 6063. This means it takes more force to remove a metal from its final shape, since there is less tendency for the metal to spring back into place. As a result, deformations on the material being machined are much less likely. 6063 aluminum is much more vulnerable to this than 6061. When selecting an alloy-specific cutter, “softening” or “inletting” cutters should be taken into account. Otherwise, general side cutters could deform the material without a secure clamping fixture and were forced into rapid cutting action while in contact with the workpiece.

V. Applications

6061 and 6063 Aluminum

A. 6061 Aluminum Applications

6061 aluminum alloy is widely used for applications requiring strength, stiffness and corrosion resistance. It has found applications such as:

Shipbuilding – for marine environments requiring resistance to seawater.

Automotive Industry – 6061 aluminum is used for chassis and vehicle bodies, as well as motorcycle gas tanks where it’s often exposed to wet conditions.

Ceramics Industry – Due to its superior strength and corrosion resistance, carbon steel is commonly employed in the production of mold designs for casting ceramic products.

Sports Industry – Aluminum 6061 is commonly used in skiing equipment, bicycle frames and rifle components due to its superior strength and corrosion resistance properties.

Railway – Aluminum 6061 can be utilized to fabricate railway ties.

Construction – Aluminum 6061 can be employed to fabricate floor beams, handrails and siding.

Food Services – Aluminum 6061 is widely employed in the production of food containers. It also finds application in paper products such as cereal box liners, cups and plates.

Home Tools and Fixtures – Aluminum 6061 is commonly used in the production of kitchen utensils like baking trays and food storage containers.

Aluminum’s lightweight strength makes it ideal for applications where weight is an issue.

B. 6063 Aluminum Applications

6063 aluminum alloy has many of the same applications as 6061, as well as others. 6063’s higher strength makes it ideal for high strength applications where other alloys such as aluminum 2024 can also be combined.

Military – Aluminum 6063 and modern processes have enhanced its hardness and durability, making it suitable for use in military products like vehicles.

Automotive Industry – 6063 aluminum is employed in the production of vehicle body panels, seat frames and door frames.

Vehicle Bumper Systems – Aluminum 6063 is commonly used due to its lightweight and impact resistance properties.

Railway Applications – Railways often utilize aluminum 6063 due to its superior impact resistance capabilities.

Outdoor Furniture – Aluminum 6063 is often used in the production of patio furniture such as chairs, tables and benches.

Piping Systems – Aluminum 6063 piping has high strength and heat resistance which make it a suitable option for water and gas piping systems.

Aluminum 6063 is widely used for fabricating railing systems due to its superior strength and corrosion resistance properties.

VI. Conclusion

A. Summary of key differences between 6061 and 6063 aluminum

Aluminum 6061 and 6063 both offer heat treatable forms in heat treatable forms; however, aluminum 6061’s high strength due to cold working makes it the preferred option for many applications; however, its poor quench properties and minimal annealing properties make it unsuitable for aerospace, automotive or marine industries due to its superior quench properties.

The other distinction is that 6061 aluminum alloy is harder, stronger and more wear-resistant than its 6063 counterpart.

Aluminum 6061 and 6063 develop a hard oxide layer when air exposure increases corrosion resistance and creates an anti-metallic coating that shields the metal from oxygen attack. Furthermore, Aluminum 6061 boasts excellent weldability, UV resistance, and thermal fatigue resistance.

B. Importance of selecting the appropriate alloy for specific applications

When selecting an aluminum alloy for a specific application, one of the most critical factors to take into account is what alloy it is. Selecting the correct alloy can make or break product performance and marketability. To make an informed decision, knowledge of each aluminum alloy’s characteristics must be assessed against expected environment of use, cost factors and working processes involved.

Aluminum alloys are often chosen based on their mechanical properties; however, 6061 has lower load-bearing capabilities than 6063 alloys due to its larger grain size and higher impurity content. 6061 aluminum alloys have found widespread application in aerospace and military applications due to their strength and resistance to corrosion; they’re even used in marine environments due to their superior corrosion resistance capabilities.

6063 aluminum alloys are often used for high-strength applications like automotive frames, architectural components and railings. Furthermore, 6063 is an economical choice when casting intricate shapes such as small brackets and electrical components requiring high strength and minimal weight.


Gary Liao

Gary Liao

Gary Liao is the Engineering Manager of TDL Company and has more than 20 years of mold design experience.

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