Can shot blasting improve the corrosion resistance of steel?

Shot blasting can indeed improve the corrosion resistance of steel, but its effectiveness depends on several factors, including the type of abrasive material used and the specific surface treatment process. Here are the key points based on recent research:

1.Surface Cleaning and Stress Induction

Shot blasting is primarily a surface cleaning process that removes rust, scale, and contaminants from steel surfaces. This process also induces compressive stresses on the surface, which can limit the initiation and propagation of corrosion paths. For example, shot blasting with brown fused alumina (corundum) has been shown to significantly reduce the corrosion current density compared to untreated steel.

2.Corrosion Resistance Improvement

The choice of abrasive material is crucial. For instance, corundum has been found to be effective in improving corrosion resistance by creating a uniform and clean surface finish. In contrast, softer abrasives like glass beads can produce a smoother surface, which may also enhance corrosion resistance.

3.Combination with Coatings

While shot blasting alone is not a corrosion protection method, it can be combined with protective coatings to further enhance corrosion resistance. For example, shot blasting followed by a thermal spray coating of Zn85Al15 has been shown to provide excellent corrosion protection, with mass loss values remaining low even after extended exposure to corrosive environments.

4.Mechanical Performance

Shot blasting can also improve the mechanical properties of steel. For instance, shot blasting with corundum can increase the ductility of steel reinforcement, which is beneficial for applications requiring high deformation capacity. Additionally, the combination of shot blasting and coating can maintain the mechanical performance of steel in corrosive environments.

Conclusion

Shot blasting can improve the corrosion resistance of steel by cleaning the surface and inducing compressive stresses. However, the effectiveness depends on the type of abrasive material used. Combining shot blasting with protective coatings further enhances corrosion resistance and maintains mechanical properties.