1. Cleaning and Surface Preparation: Shot blasting with steel shots effectively removes rust, scale, paint, and other contaminants from metal surfaces. This process prepares the surface for coating, painting, or further treatment.
2. Peening: Shot blasting with steel shots can induce compressive stress on the surface of the metal through a process called shot peening. This can improve the fatigue life and resistance to stress corrosion cracking of the material.
   
3. Uniform Finish: Steel shots provide a uniform and consistent finish across the surface being treated. This helps in achieving desired surface roughness and texture specifications.
4. Durability: Steel shots are durable and can be reused multiple times before they wear out, making them a cost-effective option for shot blasting applications.
5. Controlled Abrasion: Steel shots come in various sizes and hardness levels, allowing operators to select the most suitable abrasive for the specific application. This helps in achieving the desired level of abrasion without causing damage to the substrate.
6. Recyclability: Steel shots can be recycled and reused multiple times, reducing waste and overall operating costs compared to single-use abrasives.

Overall, the purpose of using steel shots in shot blasting is to efficiently and effectively clean, prepare, and finish metal surfaces for various industrial applications while offering durability, recyclability, and control over the abrasive process.