The invention relates to an attachment member (R) of the “lockbolt” type comprising a pin (100) and a ring (200), said pin (100) comprising a head (110) at one end and having, on its body, a first part (120) grooved with a plurality of locking grooves or channels (121p, 121c, 121d) enabling the ring (200) engaging with the pin (100) to attach itself thereto by deformation, and a second part (130) that is grooved in order to cooperate with a tool (O), characterized in that said grooved part (120) of the pin (100) is preformed so as to provide a series of non-helical grooves (121p, 121c, 121d), the beginning and the end of the series consisting of grooves (121p, 121d) that have different profiles from the identical grooves (121c) located in the central part of said series, the different profile having an identical depth but a greater width compared to the profile of the grooves (121c) located in the central portion of the series. The invention is applicable to the production of attachments and rivets.