The mechanical properties of customized processed round steel after bending may change, and the specific changes depend on various factors, including the nature of the material, the parameter settings during the bending process, the design of the mold, etc. Here are some possible changes:

1. Strength and hardness: The material may undergo plastic deformation during the bending process, which may lead to an increase in the strength and hardness of the material. This is because plastic deformation can cause dislocation proliferation, thereby increasing the material's resistance to deformation.

2. Ductility and toughness: The bending process may result in a decrease in the ductility and toughness of the material. This is because the plastic deformation during the bending process may cause changes in the microstructure of the material, such as grain fragmentation and dislocation proliferation, which may reduce the ductility and toughness of the material.

3. Surface quality and residual stress: The bending process may cause defects such as scratches and pits on the surface of the material, which may reduce the fatigue performance of the material. In addition, the non-uniform deformation during the bending process may lead to the generation of residual stress within the material, which may affect the subsequent use performance of the material.

4. Dimensional and shape accuracy: The bending process may cause changes in the size and shape of the material, which may affect the use performance of the material. For example, if the parameter settings during the bending process are not appropriate, it may lead to an excessively large or small bending radius of the material, or an inaccurate bending angle.