Abstract: The disclosure is directed to apparatus for and a method of joining a plurality of laminations of electric steel, which are individually core-plated for electrical insulation purposes, to form a laminate structure used in the manufacture of electrical machinery. Joinder of the laminations is accomplished with the laminations in face-to-face relation and arc welding a bead transverse to the stacked lamination edges. To avoid porosity in the weld bead, the arc welding process uses microwire having a diameter of no greater than about 0.050 inches in a moving welding head that maintains the microwire in close proximity to the welding surface. The operating voltage of the arc welding apparatus is controlled to produce an operating welding current of no more than about 170 amperes. The effect of using microwire of such size under such an operating current prevents overheating and degradation of the coreplate, and results in a proper deposition of a strong, non-porous weld bead.