Abstract: The object of the invention is a corrosion-resistant composite wire with diameters <10 mm, which has a concentric, homogeneous high-grade steel coating, wherein this coating, depending on the diameter of the wire and the application, can vary 15-30% by volume, and its strength can vary, depending on the core wire used and the degree of forming, up to .ltoreq.2000 N/mm.sup.2. To produce such a composite wire, for example, a high-strength, patented and surface-pretreated steel wire is sheathed with a strip of high-grade steel. In the first forming step, the longitudinally welded high-grade steel sheath is pressed tightly onto the core wire and in subsequent drawing steps, the composite wire is drawn to the final dimensions. At least between two forming steps, there is a selective annealing treatment of the composite wire by means of a rotary arc, whereby only the high-grade steel layer is heated to the annealing temperature.

Abstract: The invention concerns a process and a device for surface heat treatment of rod-shaped, longitudinally extended materials with metal surfaces by means of an arc, which rotates and is magnetically driven around the axis of the billet, wherein the arc moves between an annular electrode (anode) and the billet serving as cathode that runs through it.According to the invention, the problem of developing improved measures for stabilizing an arc, inter alia, is solved by rotating the arc by a direct current magnet arranged behind the annular electrode in the direction in which the billet runs and at the same time the magnetic field induced by the direct current magnetic counteracts the pulling effect on the arc base point by the moved billet and the annular electrode current is divided into two divided currents.The field of application is primarily surface heat-treating of rod-shaped, longitudinally extended materials with metal surfaces.