Washer, fastener provided with a washer, method of and power tool for fastening objects

A washer (1, 1', 1") has a body (2, 2', 2") having an axis (A1) and provided with a first bearing face surface (3, 3', 3") located at one axial side and adapted to cooperate with a nut (10), a second bearing face surface (4, 4', 4") located at an opposite axial side and adapted to cooperate with an object (18) and at least one third turning resistant surface (5, 5', 5")adapted to cooperate with a thread (13) of a bolt (12). The body has at least one resistive point (33, 34; 35, 36; 37, 38) arranged so that when the nut (10) is turned and turns the bolt (12) the body (2, 2', 2") of the washer stops the bolt (12) from turning and thereby the nut (10) creates a pull on the bolt which elongates the bolt (12) in an axial direction and applies to the body (2, 2', 2") of the washer an axial force which overcomes the at least one resistive point (33, 34; 35, 36; 37, 38) so that a portion (7, 7', 7") of the body (2, 2', 2") of the washer (1,1',1") is allowed to be pulled axially when the bolt (12) elongates. Also, a fastener with the washer is provided, as well as a method of and a tool for fastening objects with the use of the washer.