Disclosed is a method of making an integrally bladed rotor. According to the method, a rotor disk comprising a radially outer rim surface is provided. A portion of the disk outer rim surface is removed, leaving a protrusion on the rotor disk outer rim surface. The disk with material removed is subjected to thermal processing. A blade comprising an airfoil and a base is positioned such that a base surface is in contact with the protrusion, and heat, pressure, and motion are applied between the blade and the disk to friction weld the base surface to the protrusion.