Evaluation of component repair using direct metal deposition from scanned data

In this work, the repair volume of AISI H13 tool steel samples with hemisphere-shaped defects was reconstructed through reverse engineering and the samples were repaired by laser-aided direct metal deposition (DMD) using Co-based alloys powder as the filler material. Microstructure characterization and elemental distribution of deposits were analyzed using optical microscope (OM), scanning electron microscope (SEM), and energy dispersive spectrometry (EDS). Mechanical properties of repaired samples were evaluated via tensile test and microhardness measurement. The experiment showed that a gap between deposits and substrate exists if only employing the tool path generated from the reconstructed repair volume but the gap can be removed by depositing an extra layer covering that region. Microstructure and tensile test confirmed strong metallurgical bond in the interface. Defect-free columnar structure dominated the deposits near the interface while other regions of deposits consisted of dendrite structure with interdendritic eutectics. The tensile test showed that the repaired samples have a higher ultimate tensile strength (UTS) and lower ductility compared with those of base metal. Fractography from tensile test showed repaired samples fractured brittlely at the deposits section with cracking propagating along the grain boundaries. The hardness measurement showed that the deposited layers have a much higher hardness in comparison to the substrate.