Material for Round Nuts: Plain, blackened, and galvanized ones are typically made of ordinary carbon steel, with round nuts usually marked with a grade. Stainless steel ones are generally A2-70. To distinguish between carbon steel and stainless steel nuts, use a magnet to attract them; stainless steel ones won't be attracted. Stainless steel products usually have a bright silver color. 1. Hex Nuts: Fixed on stationary workpieces, Round Nuts: Used to lock shafts on moving workpieces. Use hex nuts to secure workpieces, and round nuts to lock them. 2. Round nuts are mainly used for end locking of shafts, often used with lock washers, usually with fine threads. The concept of nuts is quite broad, including common hex head nuts, wing nuts.

The round nut is often used with a locking washer. During assembly, insert the tongue of the washer into the slot of the shaft, and the outer tongue of the washer into the slot of the round nut, thus locking the nut in place. It is commonly used for the axial fixation of roller bearings.