Abstract: A welding method that enables the joining of at least two dissimilar, metallic alloys to form a weld that is free of cracks is disclosed. The method incorporates a pure (99.00% minimum by weight) nickel fill-wire, integrally assembled into the joint between the two alloyed metals to be joined. The alloys joined by this method are an iron-based, low expansivity, gamma-prime strengthened superalloy (i.e., Incoloy®) and a high carbon, powder metallurgical tool steel high in refractory metal alloying agents (i.e., CPM REX 20). Welding of the joint results in the formation of a nickel rich region within the weld, thus “inoculating” the weld against cracks. The weld joint formed by the method of the present invention can be used in the fabrication of a rotating anode bearing shaft assembly for use in an x-ray generating device.

Abstract: A thermomechanical process for producing high strength and thermally stable alloys, comprising the steps of: pre-heating an alloy bar or rod stock of a pre-selected size at a temperature below that at which grain growth occurs; and thereafter rotoforging the heated alloy bar or rod stock at a sufficient deformation level and temperature to fragment the grain boundary phases of the alloy. The resulting alloy is characterized by an ultra-fine, very uniform grain size, high tensile strength at room and high temperatures, good ductility, and a stress-rupture rate that is about twice as long as conventional alloys that have not undergone the thermomechanical process.