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A Comparison Of 6063 vs. 6061 In Aluminum Extrusions


There are a lot of aluminum alloys to choose from for extrusion applications, with 6063 and 6061 being among the most popular.  So how can one know which alloy is best for a particular use case scenario?  While there is a lot of information available online, working with a trusted aluminum supplier is one of the best ways to ensure getting the right material.

Although aluminum has only become commercially viable as an industrial material in the last one hundred years or so, it has quickly become indispensable for manufacturers and builders.  Thanks to aluminum’s tremendous versatility, lightweight and corrosion resistance, this readily available metal can be found in nearly every industry, from automotive and aerospace to food processing and medical.

But when it comes time to select an alloy, the number of choices can be confusing.  Aluminum extrusions come in many forms and knowing the exact needs and requirements of your application will go a long way to ensuring its success.  A comparison of two aluminum alloys widely used in extrusions, 6063 and 6061, can help in understanding the subject.

What do you need to know about aluminum extrusions?

When a metal is extruded, it means that it has been processed into a specific shape based on the cross-sectional profile of the die used; an infinite number of different finished forms can be created.  The best part is that the extrusion process will not only take advantage of the multiple benefits of aluminum, but it can produce a stronger workpiece than originally designed.

The first step in the process involves creating a die in the desired shape.  The dies are made from hot work tool steel that can withstand the extrusion process.  They can be hollow or solid and usually have multiple in-line components within the press.

Next, an aluminum billet is heated to the required temperature to soften the metal and then pushed through the die.  Because the aluminum billet becomes soft and malleable after heating, it will flow through the die and come out the other side in the negative shape of the die.  The finished lineal extrusion will be as long as the press’ runoff equipment can accommodate and can be cut to the desired length for further processing, packaging, transport and delivery.

After cooling, the extruded aluminum is stress relieved, heat treated and quenched.  Many extrusion mills also offer value-added processes like machining, surface finishing, anodizing, powder coating and others.

6063 Aluminum Alloy

6063 aluminum is alloyed primarily with magnesium and silicon, along with trace amounts of iron, copper, manganese, chromium and zinc.  It is well known to have good mechanical properties and is both heat treatable and weldable.  These attributes have led it to becoming the most popular alloy for aluminum extrusion. This is because its chemical composition makes it makes it easy to anodize and perform surface finishing processes.

When welded, primarily with tungsten inert gas welding, it will often have a strength loss of as much as 30%, but it can subsequently be heat treated to restore much of that strength.  It is generally of medium strength compared to other aluminum alloys and shows good workability and corrosion resistance. Its machinability is fair.

Since many aluminum extrusion applications have cosmetically sensitive applications, 6063 is uniquely qualified for these due to its superior ability to yield high quality surface finishes.  It accepts acid etching for a matte appearance and polishes to a highly reflective quality which can be enhanced with a “bright dip” anodizing operation.

6063 aluminum extrusions can be found in visible architectural applications, including window frames, doorframes, roofs and sign frames, as well as pipes, tubing and furniture.  It is used in premium casework, such as angles, corners, coves, out corners, face nosing and trim.  It is also popular in automotive applications like roof rails for luggage racks and other ornamental trim parts.

6061 Aluminum Alloy

6061 aluminum is a precipitation-hardened grade, primarily alloyed with magnesium and silicon, along with iron, copper, chromium, zinc and titanium.  It generally undergoes a heat treatment process that improves the metal’s grain structure to increase the material’s strength and durability.  It is generally recognized for its good mechanical properties, weldability, corrosion resistance and other beneficial qualities, which have led it to becoming one of the most popular aluminum alloys.  It is second in popularity for extruded aluminum applications to 6063.

When strength is your number one consideration, 6061 aluminum is a great choice. That’s why you’ll find this alloy in so many different applications including bicycle frames, motorcycles, firearms, camera lenses, construction and automobiles.  It’s even a primary component found in the design of aircraft components.

A Comparison of 6063 and 6061 Aluminum Alloy

Most aluminum extrusions are either 6063 or 6061.  So, what’s the difference between the two?  A quick answer is that while 6063 is slightly better suited to the extrusion process, 6061 tends to be stronger.  If strength is a primary consideration, 6061 may be the better choice.

However, when it comes to surface quality, corrosion resistance and workability, 6063 performs better.  Both these alloys are weldable, but it should be noted that 6061 is slightly more machinable.  It may be necessary to either perform extensive prototyping, and/or to partner up with an experienced metal supplier who has a wealth of experience working with aluminum extrusions.

Your Trusted Services Professional

Aluminum is one of the most versatile and adaptable metals available on the market. Of course, with so many options available, selecting the right alloy for extrusion is extremely important.  At Clinton Aluminum, our dedicated team of professionals is committed to working with our customers through the procurement process and ensuring they select the right material for the job.

For more information about how we can help with extruded aluminum alloys, get in touch with one of our friendly and knowledgeable customer service representatives today.


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