In this study, we investigated characteristics and mechanical properties of SKD61 repaired using the direct energy deposition (DED) process. Mechanical properties of the repaired product can vary depending on the base material and powder used in the DED process. To prepare for DED repairing for a damaged part, we conducted experiments using two different powders (H13 and P21). Experimental results showed that both powders were deposited without defects in the surface or interface between the deposited zone and the substrate. Hardness measurements indicated that the repaired region of the Repaired-H13 sample exhibited higher hardness than the base material, while the Repaired-P21 sample showed a sharp increase in hardness in the heat-affected zone (HAZ). Additionally, tensile test results revealed that the Repaired-H13 sample had lower tensile strength and elongation than the base material, whereas the Repaired-P21 sample demonstrated higher tensile strength and yield strength with a higher elongation than the Repaired-H13 sample. In case of Repaired-H13, it was confirmed that interfacial crack occurred due to a high hardness difference between the repaired part and the substrate.

In this study, based on directed energy deposition (DED) technology, one of the additive manufacturing technologies, a porous material fabricated by mixing various aluminum alloys and foaming agent was manufactured. First, the foaming agent formed pores inside the deposited materials and differences in foaming characteristics were observed depending on the type of aluminum. Also, the foaming characteristics according to the laser power, which is a representative process variable, were analyzed. As a result, a closed-cell porous material with a maximum porosity at a laser power of 1,100 W was manufactured. Results of the compression test showed that the porous material made by the pores generated therein collapses to absorb energy, and the internal pores disappear to become high density. Therefore, Young’s modulus and yield stress were reduced by the pores inside the sample of pure aluminum and Al6063. However, it was found that the specific energy absorption, which is an advantage of the foamed materials, increased compared to non-porous materials. The findings of this study confirmed that it was possible to manufacture DED-applied foam materials using aluminum powder and a foaming agent.