Process control of electron beam wire additive manufacturing

A method of controlling operation of an electron beam gun and wire feeder during a deposition process including deposition of pools of molten metal onto a substrate to form beads upon solidification of the molten metal, the method comprising:

• providing a substrate;
• providing a wire source that feeds wire at a wire feed rate;
• moving the electron beam gun and/or the wire feeder relative to the substrate at a travel speed;
• melting the wire utilizing an electron beam generated by an electron beam gun to form liquid phase metal on the substrate;
• cooling the liquid phase metal to form a solidified deposit;
• forming a molten pool on the solidified deposit by heating and melting the wire utilizing the electron beam generated by the electron beam gun at a beam power;
• capturing thermal data from the molten pool and the solidified deposit under the molten pool utilizing a near-infrared (NIR) sensor, wherein the thermal data captured by the NIR sensor results from the heating of the wire to form the molten pool and the solidified deposit under the molten pool;
• evaluating the thermal data to determine a thermal diffusivity of the solidified deposit behind or under the molten pool to identify at least one attribute, wherein the at least one attribute comprises a detected subsurface flaw embedded in the solidified deposit;
• determining an adjustment configured to correct an anomaly associated with the at least one attribute, wherein the anomaly is at least one of a change in bead dimensions, a void, an inclusion, porosity, cracking, and a lack of layer fusion, in the solidified deposit;
• and
• adjusting a deposition process parameter for forming a subsequent molten pool on the substrate or solidified deposit using the electron beam gun and the wire feeder according to the determined adjustment.