When it comes to choosing a fastener material, there are many factors to consider. Each project requires different materials depending on environmental conditions, strength, corrosion, vibration, and more. It’s not always safe to simply choose the cheapest or strongest material; you’ll need to consider many qualities in order to decide the best overall material fit for the job.
We can divide fastener materials into categories with regards to properties, benefits, and applications. They can be used plain or coated/plated to alter appearance and increase resistance to corrosion.
Here is a look at some of the most common types:
Stainless steel is a low carbon and chromium alloy with a high degree of corrosion resistance. Because of the low carbon content, it cannot be hardened through heat treatment.
As a result, stainless steel fasteners are stronger than un-hardened steel fasteners, but much weaker than those made of hardened steel. Stainless steel is magnetic, but less so than standard steel.
Some variations of stainless steel include:
- 18-8 Stainless - Special variety of stainless steel featuring 18% chromium and 8% nickel. Our 18-8 stainless steel fasteners are mainly used for industrial applications.
- Stainless 316 - Excellent in a range of atmospheric environments and many corrosive media. Stainless steel 316 is a corrosion resistant grade of stainless steel, and is ideal for marine, medical, and saltwater applications.
- Stainless 410 - Used for highly stressed parts and provides good corrosion resistance plus high strength and hardness. Harder than the 18-8 variety.
- Martensitic - Can be heated to provide hardness to manufacture as self-tapping or self-drilling fasteners.
- Austenitic - Considered the only type of stainless steel for panel fasteners.
Steel is the most commonly used fastener material, making up 90% of all fasteners manufactured each year. This magnetic material is popular because it’s easy to form but also extremely durable and relatively inexpensive. Steel fasteners and bolts are available with zinc or chrome plating, as well as plain options with no surface treatment.
Some variations of steel include:
- Grade 2 - Standard steel grade for hardware; may feature a manufacturer’s mark.
- Grade 5 - Also known as grade F, and is used in automotive applications. Bolts made from grade 5 steel feature radial line heads.
- Grade 8 - Bolts are harder than grade 5 and are used in demanding applications such as automotive suspensions and high stress environments.
- Alloy Steel - Heat treated for extra strength, distinguished by their gray black finish.
Bronze & Brass
Bronze and brass are both electrically conductive copper alloys. Bronze is non-magnetic and has superior resistance to corrosion, making it the top choice for aquatic projects like shipbuilding. Unfortunately, the high cost of bronze can be a deterrent. Brass is corrosion resistant as well but a bit softer than bronze. It’s mostly used for its sleek gold aesthetic, rather than its strength.
Aluminum is well known as a lightweight material that can be alloyed into many other metals to increase strength. Aluminum alloyed fasteners weigh about one-third of those made of steel and they’re easily adaptable to hot and cold temperatures. Though aluminum is a soft metal, it is inherently corrosion resistant. It is also non-magnetic.
Non-metallic fasteners are typically lightweight, non-conductive insulating materials. They are easily altered aesthetically but they are also highly susceptible to deterioration in extreme environments. Non-metallic fasteners are also generally lower strength.
Some variations of non-metallic materials include:
- Nylon - One of the most widely used plastics in the world. All grades maintain great strength and offer extremely good wear resistance.
- PVC - Offers outstanding corrosion and weather impedance, in addition to a high strength to weight ratio.
- Polypropylene - A combination of physical, chemical, mechanical, thermal and electrical properties not found in any other thermoplastic.
- Neoprene - Mainly used in chemical processing and storage industry where moderate chemical products are handled.
- Polycarbonate - High heat deflection, plus low frequency and high voltage insulating characteristics.
Assembly Fasteners Inc. (AFI) has over 30 years of experience in “Providing the World with Assembly Solutions.” We understand how important it is to choose the right material to fit your environment and your specific project.
If you want to learn more about fasteners, check out our fastener reference guide by clicking here or on the button below!