The predominant material, metal or elements in a fastener.
Aluminum
This lightweight metal is used as an alternative to other materials when weight is an issue. It has a strength similar to low/medium grade steel. It is also nonmagnetic, electrically conductive, and resistant to corrosion from the elements. It is a great choice in outdoor environments. It is also the best choice when fastening to other materials made of aluminum, due to the tendency of other materials to cause galvanic corrosion to the aluminum.
Brass
This material has a general composition of 2/3 copper and 1/3 zinc. This material has a distinctive bright golden coloring and is primarily used in aesthetic settings or in applications where low friction is necessary. As an electroplated finish it is nonmagnetic and resists corrosion well. Often used when sparking is an issue. It has excellent cold working (forming at room temperature) properties. Used in locks, gears, doorknobs, plumbing, electrical applications and musical instruments.
Nylon
This lightweight thermoplastic material offers toughness, low coefficient of friction, and good abrasion resistance making it an ideal replacement for low strength metals and rubbers. Nylon also performs significantly better than copolymers in extreme temperture toughness, fatigue endurance, and elongation at yield. This material can be easily machined and worked using standard metal working equipment. It can also easily fabricated in a wide array of colors. Natural in this instance refers to the color of this particular substance which can be off-white to beige. This material is non-magnetic, non-corrosive, non-toxic, non-flammable and non-conductive. Cast or injection molded Nylon is used for mechanical parts like gears, machine screws, or low to medium stress fasteners previously cast in metal.
Silicon Bronze
This alloy is 96% copper and around 2 – 3% silicon. With very high corrosion resistance, it is commonly used in salt-water, fresh water, sewage, and atmospheric applications. It is quite durable and similar to low carbon steel in hardness. It is a popular alloy because of its combination of strength, ductility, corrosion resistance and weldability. It is commonly seen in architecture, marine applications, pumps and boilers.
Stainless Steel
An iron based material with a minimum of 10.5% chromium. This material is known for its corrosion resistance and has varying strengths depending on the amount of chromium and nickel alloy. The chromium forms a protective layer when exposed to oxygen, keeping the steel underneath from corroding. There are over 150 grades of this material with the 304 and 316 series being the most common.
Steel
The most common material used in fasteners, this material is predominantly iron mixed with carbon. It offers the highest strength compared to other metals and elements, but is the least corrosion resistant. Also known as Carbon Steel.