Microcrystalline polished layer that forms on a metal surface is called
Beilby layer
Sir George Thomas Beilby proposed that when a metal is polished, a film forms on the surface due to plastic flow of the metal. He inferred that when a solid is caused to flow, as in polishing due to heat generated, the crystalline surface is broken down to form a harder and denser surface layer.The Beilby layer explains the hardening of metals under cold working. This worked layer thus can be defined as an amorphous, disorganized molecular surface layer of a highly polished metal, which is a result of melting and surface flow during machining of the molecular layers such as using a series of abrasives of decreasing coarseness during the polishing processes.
Materials Used in Dentistry-  S. Mahalaxmi page 578
Beilby layer
Rogue layer
Bilbe layer
Knoop layer