Apparatus and a method for forming a metallic component by additive layer manufacturing are provided. The method includes the steps of using a heat source such as a laser to melt the surface of a work piece and form a weld pool; adding wire or powdered metallic material to the weld pool and moving the heat source relative to the work piece so as to progressively form a new layer of metallic material on the work piece; applying forced cooling to the formed layer; stress relieving the cooled layer by applying a peening step, for example with a pulsed laser, and repeating the above steps as required to form the component layer by layer.