Most often used on machine screws and threaded rod, these general purpose nuts are for low-strength assemblies. Hex Nuts have flat tops with chamfered corners; bottoms may be flat or chamfered. Hex drive systems are driven with a wrench.
Steels are designated by a 4 number SAE Steel grade. The first two digits indicate the primary materials used to form the steel. The last 2 digits identify the percentage of carbon for the alloy (in hundredths). The steel used in these fasteners has a tensile strength ranging from 100,000 to 150,000 psi (pounds per square inch). Zinc Plating helps to prevent corrosion.
A threaded fastener's size name indicates information about the major, or largest, diameter, followed by the threads per inch. Fine threads are preferable when working with harder materials or when threading into a thin material. They are also stronger in tension than coarse threads, and generally provide higher shear strengths.