Methods of manufacturing of molybdenum and molybdenum-based structures by electron beam additive manufacturing, particularly structures for nuclear components

A method to manufacture a component by electron beam melting additive manufacturing, the method comprising:

• a build set-up step including seating a start plate on a powder bed within a reaction zone of a vacuum chamber of an electron beam melting additive manufacturing machine, wherein the start plate has a composition consisting of molybdenum having a purity of 99.0% or higher and wherein the powder bed includes a first powder having a composition consisting of molybdenum having a purity of 99.0% or higher;
• an initial thermal treatment step including positioning the start plate at a plate offset distance that is based on thermal expansion of the start plate during the initial thermal treatment step, heating the start plate to a first temperature that is sufficient to sinter the powder bed and is equal to or greater than 1040° C. and equal to or less than 1350° C., holding the start plate at the first temperature, and sintering a portion of the powder bed on which the start plate is seated;
• covering at least a portion of a build surface of the start plate with a base layer of the first powder;
• a pre-consolidation step including a first heating step in which the base layer is heated to a first preheat temperature and a second heating step in which the base layer is heated to a second preheat temperature, wherein the second preheat temperature is higher than the first preheat temperature, and wherein the first preheat temperature agglomerates the first powder of the base layer and the second preheat temperature densifies a portion of the agglomerated first powder;
• a consolidation step including sintering a current layer of the component from the densified portion of the agglomerated first powder, wherein a rastering pattern used for sintering during the consolidation step includes an angular rotation that is non-90 degrees and that is based on a prime number or based on an integer multiple of a prime number;
• and
• a post-build step including a cool-down step.