Wedge locking washer with increased corrosion resistance and method for its manufacture

A method of producing a wedge locking washer comprising:

• a. cold forming a wedge locking washer out of a steel blank in order to obtain a wedge locking washer comprising a central axis, a central through hole concentric with the central axis and defining an inner peripheral axial surface, an outer peripheral axial surface, a first side surface adapted to face and engage another wedge locking washer, said first side comprising a pattern of radially extending cams, each cam comprising a first surface inclined in relation to a central plane of a wedge cam locking surface and a second surface and wherein the first and the second surface of each cam meet in a radially extending cam edge and wherein the second surface of a first cam meet the first surface of an adjacent cam in an radially extending inner corner, each cam having a height h defined between a bottom plane in which the bottom of the inner corner is arranged and a top plane in which the top of the cam edge is arranged, a zone of a smooth transition of the inner corner has a horizontal length a, the inner corner has a height H of at least h/4 and at most h/2 defined as the height H in a vertical direction from the inner corner bottom to the end of the smooth transition zone, the cam edge having a smooth transition zone, which has a height H′ that is equal to or larger than the height H of the inner corner of the smooth transition zone;
• b. surface hardening the cold formed wedge locking washer by diffusing carbon and/or nitrogen into the surface of the cold formed wedge locking washer, thereby obtaining a hardened surface layer of the wedge locking washer;
• c. electro-polishing or pickling the surface hardened wedge locking washer to a surface depth lower than a depth of the hardened surface layer.