Aluminum Fasteners – Nuts and Bolts

Continuing our exploration of various materials and applications for fasteners, next we come to one of the most recognizable materials around: aluminum. With aluminum, we find such a wide range of benefits that there’s little question as to why this is the primary fastener choice for so many applications. Lightweight, inexpensive, widely available, naturally corrosion-resistant, and more – all features of aluminum that can complement your next project. Here we’ll explore key properties and applications for common aluminum alloy fasteners.

Aluminum Properties

As with other metallic hardware, aluminum fasteners are mixes of various materials to make an alloy. Luckily, only a few of the numerous possible alloys are used in your common stock fasteners. The three most common aluminum alloys found in fasteners are 2024-T4, 6061-T6, and 7075-T6.
Before describing each alloy’s properties, we’ll outline characteristics common across all three.

  • Each aluminum alloy is a non-ferrous mix of metals including pure aluminum, iron, silicon, copper, magnesium, manganese, and zinc. Changing the proportion of the various additive metals results in changes to the alloy’s strength, workability, corrosion resistance, and electrical conductivity.
  • All alloys are relatively lightweight, lower density, and naturally more corrosion resistant when compared to steel (more on this below).
  • All alloys are heat treated to give additional strength and durability, defined by the “-T4” or “-T6” temper designators at the end of the alloy number.
  • All alloys are non-toxic, non-magnetic, non-sparking, odorless, impermeable, and recyclable.
  • And finally, all alloys are very good heat and electrical conductors.

With the commonalities all outlined, now we can describe the properties of the three most common aluminum fastener choices:

  • 2024-T4 = though relatively low in corrosion resistance compared to higher aluminum grades, high-strength 2024 alloy is moderately workable, has high fatigue resistance, and has an excellent strength-to-weight ratio. This alloy is often anodized or otherwise surface finished to boost its corrosion resistance. These fasteners are found in aviation, transportation, defense, and medical equipment where high cycling and low weights are important.
  • 6061-T6 = with higher magnesium and silicon proportions, 6061 offers increased corrosion and stress resistance than lower grade alloys. 6061 is a more workable alloy, being both more easily formed and able to be welded. These fasteners are often found where high-strength and corrosion resistance are of increased importance, such as in industrial, nautical, recreational, outdoor, and hydraulic applications.
  • 7075-T6 = the highest strength of these three common alloys, 7075 is up to the toughest structural challenges. With ~45% higher ultimate tensile strength that 2024, this alloy is ideal for where high stress and fatigue will be encountered. These fasteners are typically used in high-load aviation, hydraulic, power transmission, and off-road vehicle applications.

Though there are only a few most common aluminum material types available for fasteners, selecting which alloy to go with is still an important decision to review. E&T Fasteners offers all three common aluminum alloys as well as many exotic alloy selections, with high stock levels ready to deliver. To explore our aluminum and other material fastener offerings, see our product selection here.

Comparing to Steel Fasteners

A topic frequently overlooked when discussing aluminum fasteners is how they stack up against common steel fasteners. We often see applications where aluminum may have been a fine choice, however steel was selected simply because it’s more commonly known. The ‘zinc plated steel’ section at your local hardware store is likely much larger than the aluminum section, and we think this reflects the general perception that aluminum is for special jobs only.

Let’s take a quick look at the differences here. When compared to steel, aluminum features:

  • Competitive Cost – pound for pound, general carbon steel alloys are typically less expensive than aluminum alloys. The difference is however usually low, and is often offset by the lighter weight and omission of adding a protective finish.
  • Lighter weight – you’ll gain lower total weight than steel in aluminum fasteners, just be sure to check that the strength values of the aluminum option meet the needs of the project when directly replacing steel.
  • Higher malleability – aluminum fasteners can handle more cyclic and elastic stresses, and can be more easily formed / machined.
  • Low temperature performance – aluminum is excellent at maintaining strength at low temperatures, whereas steel becomes brittle and can lose strength.
  • Lifespan – since the carbon in steel materials is susceptible to corrosion and decay, aluminum typically has a longer lifespan with less maintenance required than steel.
  • Higher corrosion resistance – aluminum naturally forms a protective oxide layer on its surface, offering integral corrosion resistance, where steel has no such capability and must have a finish applied to protect it.
    Aluminum is not for every project but has plenty of unique features that can benefit many applications where steel might otherwise be the default selection.

One last note: aluminum is more susceptible to galvanic corrosion, meaning that mixing it in contact with other dissimilar metals can lead to faster corrosion and subsequent failure. Always be sure to consistently use similar aluminum materials in hardware assemblies touching each other.

E&T Fasteners is here to help you navigate fastener options to best meet your application and project needs. Price quotes, availability, lead times, delivery confirmations, unique application suggestions – whatever your need, we’re here to take your call or email. For support and advice from our fully trained staff, speak with an E&T sales representative today.

About E&T Fasteners

With sales and support teams spanning the Continental US, E&T Fasteners is here to serve your hardware, fastening, and component needs both domestically and internationally. We are a stocking distributor of metallic, plastic, and exotic alloy fasteners, backed by our technical staff directly experienced in your unique applications. We can assist your specifying and selection efforts, providing engineered solutions, record-fast lead times, and stellar customer service from quote through delivery. Please let us know how we can help!