Abstract: A process for hardening elongate metal elements having a circular section, according to which the said elements are made to advance through a heating station and a hardening station by a conveyer device formed by a succession of advancement and support devices individually controllable in a direction transverse the said elements in such a way as to maintain the axis of each of the elements always coincident with a predetermined axis of advancement each advancement device being individually controllable in such a way as to impart to each point of each element displacements with a controllable velocity along cylindrical helices the pitch of which can be varied from zero to infinity and, in particular, to impart to each element during the traverse through a current of cooling fluid generated within the said hardening station transversely of the axis advancement, a rotary and translational movement with a velocity variable according to laws depending on the distribution of mass along the element itself.