Carbon steel nuts come in various shapes and sizes depending on their intended use and the type of fastening they are meant for. Some common shapes include:

1）Hexagonal (Hex) Nuts: These are the most common type of nut, with six flat sides and a threaded hole in the center. They are used with bolts and screws to fasten materials together securely.

2）Square Nuts: Square nuts have four flat sides and are used in applications where a standard hex nut might not fit or where a greater bearing surface is required.

3）Round Nuts: Round nuts have a circular shape with a threaded hole in the center. They are used in applications where space is limited or where a decorative finish is desired.

4）Wing Nuts: Wing nuts have "wings" on either side that allow for hand tightening and loosening without the need for tools. They are often used in applications where frequent adjustments are necessary.

5）Cap Nuts (Acorn Nuts): Cap nuts, also known as acorn nuts, have a domed top that covers the end of the bolt or screw, providing a finished appearance and some protection against contact with threads.

6）T-Nuts: T-nuts have a T-shaped body that fits into a slot or groove in a workpiece, allowing for a threaded fastener to be inserted from the opposite side.

7）Flange Nuts: Flange nuts have a built-in washer-like flange at one end that distributes pressure and helps prevent loosening due to vibration.

8）Lock Nuts: Lock nuts have features designed to prevent loosening, such as nylon inserts, serrations, or deformed threads.