Characterization of Copper & Stainless Steel Interface Produced by Electron Beam Powder Bed Fusion

Abstract Unalloyed copper (Cu) powder was deposited and melted onto a pre-existing stainless steel substrate using electron beam powder bed fusion (EB-PBF) additive manufacturing (AM) to form dense, bimetallic structures. The AM fabricated Cu was fully dense, and with strength properties consistent with recent reports on EB-PBF of Cu. The overall bimetallic structures exhibited total elongation of 25-35%, and was dominated by plastic deformation in the Cu region. Tensile failures were typically observed in the Cu portion of the bimetallic bodies demonstrating that the interface was not the source of mechanical failure. The interface region of the bimetallics contained areas of liquid phase separated Cu and Iron (Fe) + Chromium (Cr) rich regions resulting from a metastable miscibility gap in the Cu and Fe phase diagram. Metallurgical and mechanical examinations of the bimetallic structures showed the interface region transitions from an Fe rich mixture to a Cu rich mixture within a few AM layers.