The wave spring washers is used in electric motor to  offer a pre-pressure force to bearing, raw material is 65Mn, hardness HRC43-50.

This flat washers and wave washers is specially for thrust beal bearing , .material could be 1074 CRS 

HARDNESS: 81.0-83.1 HR30N (797.1-880 DPH),PART MUST BE FLAT WITHIN 0.18, roughness Ra0.46