The best and worst materials for your fasteners

You might think that when it comes to fastening, the main thing you should worry about is what type of fastener it is: nuts, self-clinchers, rivets, screws, even welding if you’ve got the staff trained for it – but the truth is a lot more complicated. A much bigger factor you need to consider is what material your fastener is actually made from.

From steel and stainless steel to bronze and aluminium, at first glance, it might seem simple enough – but there are a lot of other factors that go into what material your fastener might be and they all have their own positives and negatives.

So let’s discuss these:

Steel

Grades: 2, 5(F), 8(G)

Most manufacturers use steel as their fastener material of choice, and it’s not hard to see why. Steel, regardless of grade, is a great all-rounder, with a high durability and strength and a fairly low cost of production.

The different grades are dictated largely by how strong the steel is made. By heat treating the carbon within the steel, they can become stronger – but also more expensive.

Grade 2

This is the standard grade you’ll find most fasteners to be at. As it isn’t heat-treated like other grades, it is one of the cheapest materials you will find.

Grade 5

This steel grade is hardened, via heat-treating to increase its strength. The increase in durability and corrosion resistance means they are often used in automotive applications.

Grade 8

Similarly to Grade 5, Grade 8 steel is heat-treated, but even more so than their Grade 5 counterparts. This makes Grade 8 steel one of the strongest material types for fasteners, and also one of the most expensive.

Stainless Steel

Grades: 18-8, 316, 410

Stainless steel is made when the carbon and other non-steel molecules are removed from steel through electricity rather than heat. Stainless steel has many of the positive properties of normal steel, but unlike steel, it is far more corrosion-resistant, making it perfect for outdoor use or use in marine transport.

Grades of stainless steel are defined mostly by the percentage of Chrome or other materials that the steel is made up of.

18-8 Stainless Steel

This standard grade of stainless steel is called 300 series stainless steel, with 303 and 304 series being the most common. 18-8 is a more common name as it refers to the stainless steel having 18% chrome and 8% nickel. This steel has great applications for freshwater usage, but issues can arise when exposed to chlorides like salt – which isn’t just impacted when exposed to salt-water, but also the salt in the air around a body of water, which is why this material is rarely used for anything other than cutlery.

316 Stainless Steel

Unlike its 300 series peer, 316 stainless steel features more nickel and more molybdenum, which gives it better resistance to the harsh environments than 18-8 steel would be able to handle. This makes marine applications in and around salt water much more reliable.

410 Stainless Steel

Completely separate from the other two grades mentioned, 410 stainless steel actually uses less chrome but supplants that with much more carbon (up to 15%). This means that it’s much harder than the other steel grades, but because of its larger percentage of carbon, it’s less corrosion-resistant.

Silicon Bronze

Unlike standard bronze, silicon bronze alloy is made by – you guessed it – adding a small amount of silicon. This makes it stronger than most bronzes, and as an alloy, bronze is already very corrosion-resistant, but silicon improves this further. The biggest drawback to using bronze are two-fold: bronze is an incredibly thermally conductive alloy – which could cause issues in certain environments – and bronze also has a much higher cost than other alternatives.

Brass

Bronze is an alloy made of copper and tin, brass is made from copper and zinc. Because of this, brass is actually much softer than most other materials and we find it primarily used for its gold-like look on older marine craft or for those looking for a retro look for their products today.

Aluminium

Aluminium is lighter and more malleable than stainless steel. This instantly has its positives in handheld or worn items, thanks to its weight-to-strength ratio is actually quite high (99 to stainless steel’s 63). In the marine transport space, where many boats? incorporate? aluminium, utilising fasteners made of the same material makes managing catalytic corrosion? much easier and their high corrosion-resistance often makes them a good choice for pleasure craft.

It's also important to note that aluminium is a great option for those looking to create a more sustainable project, as around 75% of aluminium that has been manufactured is still in use today. Which, when compared to steel’s 40%, you can see why it is a more desirable option for products that hold sustainability as a priority.

There are thousands of potential options for the materials you use for fasteners, but these cover the ones that we find ourselves discussing most often. Understanding your product’s application is the best way to begin deciding which is the right material to use, but if you feel your design team needs some expert guidance in choosing a fastener – whether it’s type, material, or you’re prioritising how it looks, we can help your team make sure you’re getting the very best, at the right price, at the right time.

Get in touch with us by emailing [email protected] or calling 0808 123 1221.