This brake disc was damaged by worn pads.
If your car is making a grinding sound when you apply the brakes, you should look into the matter quickly. Leaving disc brake repair until later can result in costly brake component replacement.
If your brakes are making a grinding sound when you come to a stop, you are at the very end of the life of your brake pads. By the time you hear this sound, you may have to replace your brake discs.
You'll definitely have to replace your brake pads, so be prepared to make this repair. A quick brake inspection will let you know whether you have damaged your brake discs.