Studs are mechanical fasteners which are threaded on one or both ends. One end is secured to an object. The other end is used typically with a nut. Studs are available in both English and Metric threads. Metallic studs are made from aluminum, brass, bronze, silicon bronze, copper, steel, titanium, and specialized or proprietary materials. Non-metallic studs are made of plastic, fiber-reinforced plastic, nylon, polyvinyl chloride (PVC), polyvinylidene fluoride (PVDF), polytetrafluoroethylene (PTFE), and synthetic rubber. Studs can be anodized, coated with phosphate or black oxide, chrome galvanized, or plated with gold, nickel, silver, tin, zinc, or zinc chromate.
Selecting metal studs requires an analysis of material specifications. Aluminum is malleable, ductile, light, and trivalent with good electrical and thermal conductivity, high reflectivity, and resistance to oxidation. Brass has good strength, excellent high temperature ductility and reasonable cold ductility, good conductivity, excellent corrosion resistance, good bearing properties and low magnetic permeability. Bronze is a metal composed of copper as the main alloying metal and one or more other metals, such as tin, zinc, or phosphorus. Silicon bronze is a typical stud alloy. Copper is a reddish metallic element that is ductile and malleable and is one of the best conductors of heat and electricity. Copper also exhibits good corrosion resistance. Titanium is hard, light, strong and corrosion-resistant. Titanium studs are used widely in the aerospace industry and in medical applications, such as replacement joints.
Steel studs are made from iron that contains carbon in any amount up to about 1.7 percent as an essential alloying constituent. Many grades of carbon and alloy steel are used as fastener materials. Some grades must be coating to protect studs against corrosion. Others, such as stainless steel studs, are chemical and corrosion resistant, and can have relatively high stress ratings. Many different grades of stainless steel are used in fasteners such studs; however, stainless steels cannot be hardened to the same degree as carbon steels. Consequently, hardened steel is another common material choice for metal studs.
Specialized and Proprietary Materials
Specialized and proprietary materials for metal studs include Inconel® and Incoloy®, alloys which combine good strength and excellent resistance to oxidation and carbonization in high temperatures and many aqueous environments. Inconel and Incoloy, registered trademarks of Special Metals Corporation, are generally used at service temperatures below 650°C (1200°F). Monel® is an alloy with high strength and resistance to a range of corrosive media including seawater, hydrofluoric and sulfuric acids, and alkalis. Monel is also registered trademark of Special Metals Corporation.