Toll free: 800-826-3370

How to choose between 6061 and M5 Aluminum


Much of the hard work that goes into product development happens before you actually begin production. Choosing the right tools and materials is among the most critical aspects of any job, and a failure in this regard can cost manufacturers an inordinate amount of both time and money.

While the vast diversity of aluminum alloys has been one of the leading drivers of the many industrial advancements we are enjoying today, it also means that doing your research is more important than ever. No matter what job you have in mind, you can bet that there’s an alloy that fits your specifications. At Clinton Aluminum, we take pride in partnering with manufacturers to make sure they have the exact material they need for any given task.

What Are 6061 And M5?

While the increasing diversification of aluminum seems like a recent trend, the reality is that aluminum has traditionally been handled in alloy form, the reason being that pure unadulterated aluminum is not found in nature. In fact, in the 19th century, pure aluminum was considered more rare than gold.

Experiments in the early 20th century helped bring aluminum to the mainstream. Aluminum 6061, first developed in 1935, was one of the early alloys that helped lead to a revolution in the aviation industry that was spurred on by World War II. 6061 is precipitation-hardened using magnesium and silicon as its primary alloying elements. Thanks to its weldability and other attributes, 6061 is among the most popular and most versatile alloys. Like many other aluminum types, 6061 varies quite a bit depending on the temper. It is commonly used in extrusion processes.

By comparison, M5 is a much newer alloy. Part of the M series that was first developed by Alpase in 1988, M5 offers many benefits, including high density, high corrosion resistance, and good dimensional stability without stress relieving. This is combined with a lower weight to strength ratio and good polishing and anodizing qualities. M5 was originally developed to increase the speed of the low volume production of molds. Today, it is looked at as an affordable alternative to wrought and forged aluminum blocks, and in fact is superior in a number of areas.

M5 aluminum plate does not suffer from porosity or grain, meaning that its hardness and strength are very consistent at even the maximum thickness, the reason for its high dimensional stability. Even when faced with high temperatures, M5 is extremely strong and offers increased resistance to thermal fatigue. M5 is more corrosion resistant than comparable mold materials, but it can also be anodized, coated, or textured as needed. Because of its milled surface, there is less machining required when working with M5.

How Do Their Specifications Compare?

T6 aluminum plate is a good example of a 6061 temper. It features a tensile strength of at least 42,000 psi and a yield strength of at least 35,000 psi. For M5, the typical tensile strength is 41,000 psi, but the yield strength is 18,000 psi. The Brinell hardness of the former is 95 HB, while for the latter it is 70 HB. The density for 6061 T6 is 0.0975 lb. per cubic inch and for M5 it is slightly lower at 0.096 lb. per cubic inch.

The hardness of 6061 T6 significantly fluctuates within a block, especially in thicker sections. When dealing with gauges of less than 8”, the hardness tends to maintain its consistency. However, in sections thicker than 8”, it is more difficult to be certain of the hardness through the center of the block. This is because of the heat treating and quenching process, which for 6061 is only effective to about 3” to 4” from a given surface (the reason for the uncertainty past 8 inches).

In the meantime, M5 is particularly recognized for its dimensional stability, making it better suited for applications where there is a high demand for consistency. M5 can be purchased at up to 30-inch thicknesses, 88-inch widths, and 195-inch lengths.

6061 has an elongation at break of 17% to 20% (at temperatures of 300 F and below) while for M5 it is 12 to 15%. The former’s thermal conductivity is 96 Btu/ft., and for the latter it is 81 Btu/ft.

What Are The Common Applications For 6061 and M5?

Due to its tremendous versatility and high weldability, 6061 aluminum can be found in a wide variety of applications. For example, it is commonly employed in bicycle frames and components, fly fishing reels, the sound suppressors for firearms, various weapon parts, aluminum docks and gangways, ultra-high vacuum chambers, remote-controlled aircraft, and many kinds of toys and models.

In contrast, M5 mold plate, with its high dimensional stability, is frequently used in injection molds, rubber molds, blow molds, and structural foam molds, vacuum forming tools, compression molds, heating and cooling plates, and semiconductor transfer chambers.

How To Make A Choice Between 6061 And M5?

No matter what your application, it’s highly recommended that you take the time to carefully test and compare a variety of aluminum alloys before making a final choice. Our experience has taught us that until you actually start working with the metals themselves, no amount of research will inform you exactly how they will react to your production processes. Of course, one more great attribute of aluminum alloys is how well suited they are to prototyping scenarios, in large part as a result of their formability, adaptability, and relatively low cost.

Whatever alloy you end up selecting, you can rest assured that you will be benefiting from aluminum’s many advantages, including its dimensional stability, weldability, corrosion resistance, strength to weight ratio, and cost efficiency. By taking the time to make the right choices early in the production process, you will not only lower your costs and increase your productivity, but your final product will be more competitive and more attractive to your customers.


At Clinton Aluminum, our motto is finding the right alloy for the right application. That means we work with our clients through every step of the process to ensure the final result. Our enthusiastic team has the knowledge and experience to be more than a seller, but also a partner. To learn more about our commitment to service and value, get in touch with us today.

Search By Product Category
Search by Industry

Get Our Free Newsletter

© 2023 Copyright. Clinton Aluminum | All rights reserved.