Why does rough grinding make stainless steel more prone to corrosion?

Stainless steel is widely known for its impressive corrosion resistance, but it is not invincible. When exposed to environments containing chloride ions, such as seawater, the risk of corrosion increases. To achieve the sleek, clean appearance the material is famous for, manufacturers typically grind the surface to smooth it. However, this finishing process reduces corrosion resistance, and the underlying mechanism has remained poorly understood.