A method for heat treating metal materials by passing electrical current through a metallic workpiece to heat the workpiece via Joule heating to a preselected temperature for a preselected period of time, based upon the formula I.sup.2.times.R.times.t, wherein I is current, R is resistance and t is time. The current may be a direct or an alternating one. Various configurations of the method are envisioned wherein multiple current inputs and outputs are attached to the metal material so as to selectively heat specific portions of the piece including irregular shapes and differing diameters.