The most common material for manufacturing fasteners, such as bolts and screws, is steel. Different grades of steel are available, depending on the st
When it comes to fastener materials there are also many different options depending on the chosen use or application of the bolt. These include the usual steel and titanium, as well as plastics and even more exotic materials.
These materials are often separated into different grades which describe anything from mixing alloys to using various hardening processes. Fastener materials are an important step in choosing the right bolts for the application based on differences in strength, corrosion resistance, and cost.
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| What Material is Used for Fasteners Bolts |
More popular fastener materials include stainless steel which is highly corrosion resistant and is stronger than hardened steel. However, due to their low carbon content, stainless steel bolts cannot be hardened making them weaker than hardened steel bolts.
- Grade 2 is a standard steel bolt and is the most common and least expensive.
- Grade 5 steel bolts are hardened to increase strength and are most commonly used in the automotive industry.
- Grade 8 bolts are even harder than Grade 5 steel fasteners and thus stronger and are used in more demanding applications.
- Alloy steel is the strongest of the bolts because they are made of high-strength alloy and are further heat treated. While alloy steel bolts are extremely strong, they are also very brittle.
- Silicon bronze is another common bolt material and is sometimes referred to simply as bronze. Silicon bronze is a permeate that is mostly copper and tin with a small amount of silicon in it. It is the material of choice for wooden boat construction and re-fastening due to its superior corrosion resistance and its strength. You will also see bronze bolts used in fine woodworking where it is used for its appearance.
- Aluminum bolts are lightweight, soft, and corrosion-resistant metal. Similar to stainless steel bolts, aluminum bolts are in demand due to the corrosion resistance that is inherent in the metal. Aluminum bolts are manufactured from a variety of aluminum alloys such as magnesium iron, zinc, and copper with silicon added to increase strength.
- Brass bolts mainly consist of copper and zinc. The use of brass bolts is quite limited because it is relatively soft compared to other metals. It is primarily used for its appearance and is also highly corrosion resistant and electrically conductive.
In addition to the actual material of the bolts, there are several types of coating that are often applied. Many steel bolts are plated with zinc because of their superior corrosion resistance. Typically if the bolt has been plated with zinc the fastener manufacturers will have a shiny silver or gold appearance, commonly known as clear or yellow zinc.
Another common coating is hot-dip galvanizing which essentially involves laying down a layer of zinc. It puts a very thick layer of zinc coating on the metal which is ideal for better corrosion resistance. Due to the extra thickness of the zinc layer, these bolts require special nuts that are tapped slightly larger to fit the additional coating. These fasteners are commonly used to accommodate for excess moisture in coastal environments.
Finally, chrome plating is a coating used for appearance. Like zinc plating, it adds to corrosion resistance but the main drawback of chrome is its high cost.
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