A method for heating metallic material, such as a slab or a billet, using at least one direct flame impingement burner. The heating power of the flame of the direct flame impingement burner is pulsated in cycles, so that the heating power is alternated between at least two different, predetermined heating powers. Each heating power is maintained during a certain predetermined time period. Some heating powers are lower than others, and the time periods are short enough so that the combination of the heating powers and their corresponding time periods results in not overheating the surface of the metal slab above a predetermined temperature during the time periods of the higher heating powers. The pulsated heating of the metallic material is interrupted when a certain stop condition is fulfilled, and the material is thereafter heated to another predetermined, final, homogenous temperature by the use of another, conventional heating method.