Abstract: The seat for automobile vehicles includes a seat frame and a backrest frame installed so as to pivot on the seat frame. A mechanism locking the backrest in position. The mechanism includes two half-housings which can rotate in relation to each other around a pivoting axis and attached to a flange of the seat frame and to a flange of the backrest frame respectively. At least one of the two half-housings includes studs inserted into holes formed in the corresponding seat frame flange and a space is then made between at least one stud and the corresponding hole into which a weld mass is deposited. The weld mass joins the seat frame half-housing to the seat frame flange.