A nut is a metal fastener with an internal thread (commonly made of materials such as carbon steel and stainless steel). It achieves mechanical connection by mating with a bolt or stud and requires a wrench to tighten it for secure fastening. Nuts come in various types, including hexagonal nuts (standard fastening), lock nuts (to prevent loosening), and round nuts (for space-constrained applications). Thread specifications include coarse threads (for high load capacity) and fine threads (for precision equipment).
They are widely used in construction (rebar fixing), mechanical manufacturing (component assembly), and other fields. However, common problems such as loosening and corrosion should be noted, and regular maintenance can extend their service life.