The raw material of rebar coupler is 45# carbon steel. It means that the rebar coupler will rust within a few minutes if it encounters water. Therefore, preventing rust in the process of producing the coupler is an important step. The reason that main causes of rust in the coupler are as follows:

1. During the thread tapping process in the production of rebar couplers, cutting fluid is used. The cutting fluid is a water-soluble oil agent with certain rust removal and rust prevention functions. If the quality of the cutting fluid is not strong and the concentration is low, it will make the rebar couplers unsuitable for storage and prone to rust.

2. The packaging bag for rebar couplers is a laminated woven bag. If the quality of the woven bag is poor and the sealing is not tight, it will cause rusting of the rebar couplers.

3. During the transportation process of rebar couplers, if they are not handled properly, the packaging bags of the rebar couplers may get damaged. If they are then exposed to rain or moisture, they will also rust.

4. When storing rebar couplers, if they are in a damp environment for a long time, they are also prone to rust.

5. During the construction process, rebar couplers are exposed to the natural environment for a long time. If they encounter severe weather conditions will rust.