6061 T6 Grade Aluminium

Updated: Nov 17

Construction and infrastructure industries are often regarded as the backbone of the developing economies, and if the backbone is supported by weak structures itself, it can become a thing of worry. Today, Aluminium formwork industry is one of the fastest growing industries in India and the world, and all variety of formwork structures are available in the market to choose from. It becomes of utmost importance to choose the right quality equipment's and structures to render the best result on field.

Today we will discuss more about the 6061-T6 aluminium alloy, used by KnestAluform for its formwork structures creation, and also shed light on why and how it is regarded as the best choice amongst the industry leaders.

Aluminium and types of aluminium alloys:

Aluminium alloys are simply a chemical composition which is obtained by mixing other elements such as iron, silicon, copper, magnesium, manganese or zinc to the pure aluminium in its molten state. By percentage, the mixed elements can make up as much as 15% of the total weight of the alloys.

For classification purposes, aluminium alloys are assigned a four-digit identification number — in which the first digit signifies its general class, or series, usually characterized by its alloying elements.

There are majorly three different categories of aluminium alloys:

Commercially pure aluminium: 1xxx series aluminium alloys are obtained when the aluminium composition in the alloy is kept at 99% or higher. These alloys show an amazing resistance to corrosion and are also found to have high thermal and electrical conductivity. Due to the same reason, 1xxx alloys are commonly used in the transmission and power grid lines.

Heat-Treatable alloys: 2xxx, 6xxx and 7xxx. series alloys come under this category. Out of all these alloys, the 6x0 series alloys are considered very versatile, formable, weldable and possess moderately high strength, which makes them an ideal option for use in the architectural and structural applications.

Alloy 6061 specifically is one of the most widely used alloys when it comes to creating frame structures.

FUN FACT: iPhone 6 extrusion was made out of a 6xxx series alloy.

Non-Heat-Treatable alloys: 3xxx, 4xxx and 5xxx series alloys fall under this category. Cold working is the method employed to make these alloys stronger. If we explain it by an example, when we roll aluminium down to thinner gauges, it builds up dislocations and vacancies in the structure which then restricts the movement of the atoms making the metal stronger than before. Alloying elements such as magnesium increases this effect many fold and hence result in a stiff and even higher strength material at the end.

What is 6061, its characteristics, benefits, where is it used and why should it be used?

Aluminium 6061 was developed in 1935 and was referred to as “Alloy 6Is” back then. Today people commonly call it as the “structural aluminium” due to its mechanical properties which are considered ideal for building products, electrical products, piping etc. Since it is a wrought alloy, it can be easily extruded, rolled or forged into different shapes as needed, unlike a casting alloy.

T6 —A heat treatment two-phase process is adopted to increase the strength of aluminium, copper and silicon alloys by up to 30%. We will be discussing the T6 process in detail ahead, but for now, it is important to understand that 6061-T6 Aluminium alloy is one of the best-suited alloys for structural and construction needs.

The strength and durability of the 6061 can be gauged from the fact that it is used in the manufacturing of the Aircraft bodies which experience extreme pressure and atmospheric conditions at 35,000 feet above the ground. It shows that 6061 -T6 is not only fit for the normal day to day conditions usage, but can be used under extreme pressure and adverse climatic conditions as well.

Some general characteristics which make the 6061 an ideal candidate for structural needs are mentioned below:

Strength Medium to High

Corrosion Resistance Good

Weldability & Brazeability Good

Workability Good

Machinability Good

High strength and corrosion resistance properties of 6061 alloy favour its use in structural, architectural and motor vehicle applications industries widely.

Though 6061 find its use in various major industries, some of the most common applications of the 6061 alloys are mentioned below:

Structural needs

Construction equipment

Aluminium Formworks

Welded assemblies

Marine frames


Heat Sinks

Aircraft and truck frames

Heat Exchangers

What is the T6 process? Why is it the best suited for 6061?

As we had discussed before T6 is a two-phase heat treatment process which is employed to increase the strength of aluminium alloys by up to 30%.

The two stages of the T6 process can be understood as below:

Phase 01 — Quenching: In this process, the alloy is heated at 500 degree Celsius for about 9-10 hours, this long and continuous exposure to heat makes the copper dissolve in aluminium, then the alloy is cooled rapidly using water which supersaturates the aluminium with copper and forms a single-phase alloy.

Phase 02 — Ageing: This process involves the heating of the alloy at 180 degree Celsius for 9-10 hours and then cooling it by air allowing it to become hard by precipitation process.

This process results in the formation of copper aluminium crystalline structures, whose size eventually determine the strength of the material, the smaller the crystals, the stronger the alloy.

The most commonly preferred temper of 6061 aluminium alloy is T6, as it provides the maximum precipitation hardening, yielding the maximum strength in return.

T6 exhibits an ultimate tensile strength of 290 MPA (42 KSI) at the very least, along with a strength of at least 240 MPA (35 KSI). In the 3.5mm or lesser thickness range it shows an elongation of 8% while for the thicker sections the elongation increases to 10%.

Due to all the above-mentioned attributes and features of 6061-T6 aluminium alloy structures, they are very commonly used in the formation of formwork structures used across housing and infrastructure industries.

Why is 6061 T6 grade aluminium best suited for formwork construction?

6061 T6 grade aluminium is best suited for formwork construction because of the below-mentioned properties:

Machinability: 6061 exhibits good machinability properties in the T6 temper., making it easier to work upon.

Forming: In the annealed condition 6061 -T6 alloy can be formed and worked with super ease. Bending, stamping, deep drawing and spinning operations can be carried out with pretty much standard procedures.

Welding: 6061-T6 shows excellent weldability, making it the preferred choice for formwork creation. Gas tungsten arc welding technique can be used to easily weld the thinner sections, while the gas metal arc welding technique can be used to weld thicker sections with ease.

Heat Treatment: Since aluminium 6061 is heat-treated at nearly 500 degree Celsius for a long period of time followed by water quenching, it is seen to exhibit amazing heat treatment properties.

606 1-T6 is also the best option to forge, hot-work, cold-work, anneal and age, as 6061 -T6 presents excellent corrosion resistance against atmospheric conditions and good corrosion resistance to seawater. Ever since its inception, Knest aluform has been known for its ethical and best quality practices in the aluminium formwork industry. When it comes to choosing the type and temper of aluminium to create formwork structures, Knest has always preferred the 6061-T6 alloys because of the exceptional qualities that it exhibits in general.

Knest aluform has been a trailblazer in adopting the formwork technologies and techniques in the Indian market and has now become a well-known name in the industry. Precision and quality of construction have become an epitome of the Knest's name in the past few years due to its subtle communication and “what you are promised, is what you get” policy.

Everything that comes out of KnestAluform's factory is made using 606 1-T6 grade aluminium alloy. From standard panels to special panels, stiffeners and everyday use small parts, everything is manufactured using the 6061-T6 material. So, next time you see a set of formworks from Knest, you can be 100% sure that it is made out of the best material in the market, which is 6061-T6.

When it comes to ensuring the quality of the material, Knest has a very strict policy in place. Firstly, Knest works with a very limited set of empanelled extruders who are well known and have shown a consistent record of supplying the best quality 6061 material in the country.

Secondly, it is made sure that our suppliers source their 6061 alloy from the primary reputed manufactures and that each lot is accompanied with its chemical and mechanical test reports. In the end, when the lot arrives at the Knest facility, independent in house quality checks are performed to once again cross check and affirm the quality of the received material.

By adopting these rigorous and thorough quality assurance processes, Knest makes sure that every lot that leaves the factory is at par with the expected quality from Knest as a brand.

To understand more about the process and quality of Knest formwork structures, feel free to reach out to us, and our experts will help you and guide you in making the right decision for your construction and structural needs.