This is a study of worn out impeller blades from an industrial shot blast machine. They’re cast from incredibly hard and abrasion resistant material. As hard as they are, though, the blades do wear out, resulting in some of the patterns captured here.
These images are abstracted from macro photos of several different blades. I added color to accentuate light and shadow and to help bring out detail, as well as to give each image a different character. In the original, they are simply finely textured grey steel.