Electron beam additive manufacturing

A method of additive manufacturing, comprising:

• providing a raw material in solid state form;
• exposing the raw material to a leading energy beam thereby liquefying the raw material;
• forming a melt pool with the liquefied raw material, the melt pool having a leading region and a trailing region;
• and
• exposing the trailing region of the melt pool to a trailing energy beam;
• wherein a distance between the trailing energy beam and the leading energy beam varies as the trailing energy beam trails the leading energy beam,
• wherein the additive manufacturing process is conducted in a vacuum chamber;
• wherein the raw material is a metal alloy having one or more alloying agents that contribute to increasing strength of the metal alloy;
• wherein the one or more alloying agents each have a processing vapor pressure, which is the intrinsic vapor pressure of the alloying agent at a processing temperature, the processing temperature being at a temperature of the melt pool;
• and
• wherein the vacuum chamber is set to a pressure level during the additive manufacturing process, the pressure level being 500 microtorr or greater for reducing vaporization of the one or more alloying agents during the additive manufacturing process.

A method of electron beam additive manufacturing a three-dimensional article, comprising:

• i) providing a raw material as a wire;
• ii) feeding the wire of raw material to a feed region with an actuator;
• iii) exposing the wire of raw material to a leading electron beam to heat and liquefy the wire to form a liquefied raw material;
• iv) forming a melt pool with the liquefied raw material, wherein:
• the forming the melt pool with the liquefied raw material is performed such that melt pool overlies a substrate, and the melt pool is formed as at least one of the leading electron beam and the substrate move relative to each other in a travel direction, and
• the melt pool has a leading region and a trailing region, the leading region of the melt pool is a liquid-phase region and the trailing region of the melt pool is a transitional solid-liquid phase region between a liquid interface and a solid interface of the melt pool;
• v) exposing the trailing region of the melt pool to a trailing electron beam having a different characteristic than the leading electron beam;
• vi) solidifying the melt pool to form a re-solidified layer that trails the melt pool;
• and
• vii) building the three-dimensional article re-solidified layer by re-solidified layer.

A method of additive manufacturing, comprising:

• providing a raw material in solid state form;
• exposing the raw material to a leading energy beam thereby liquefying the raw material;
• forming a melt pool with the liquefied raw material, the melt pool having a leading region and a trailing region;
• and
• exposing the trailing region of the melt pool to a trailing energy beam;
• wherein a distance between the trailing energy beam and the leading energy beam progressively increases at one or more intermediate distances between a first distance and a second distance;
• and wherein the trailing energy beam cycles back to the first distance after reaching the second distance.

A method of additive manufacturing, comprising:

• providing a raw material in solid state form;
• exposing the raw material to a leading energy beam thereby liquefying the raw material;
• forming a melt pool with the liquefied raw material, the melt pool having a leading region and a trailing region;
• and
• exposing the trailing region of the melt pool to a trailing energy beam;
• wherein a distance between the trailing energy beam and the leading energy beam varies as the trailing energy beam trails the leading energy beam, and
• wherein the trailing energy beam has a power level, power density, and/or pulsation that is configured to prevent hot cracking as the melt pool solidifies by disrupting a dendritic microstructure in the trailing region of the melt pool.