Correlation Between Processing Parameters in Direct Metal Deposition of IN625 Nickel-Base Superalloy

In the present study, the direct metal deposition (DMD) process was used to deposit the IN625 superalloy on the IN738LC substrate. The relationships between main processing parameters such as laser power (200–350 W), powder feed rate (40–220 mg/s), and scan speed (2–6 mm/s) with melt pool geometric characteristics (i.e., height, width, penetration depth, and dilution) were examined and discussed using linear regression analysis. The results showed; the melt pool height had a linear relationship with the P^3/4·F^3/4·V^5/6 combination parameter. Similarly, the penetration depth and dilution controlled by the P^0.3·V^0.5·F^−0.6 combination parameter. These obtained empirical dependencies showed a high amount of correlation coefficient (R > 0.90). But, there is no clear relationship between the width of melt pools with the scan speed and powder feed rate. Actually, due to the balling phenomenon, the melt pool's actual width in these single tracks is unclear. During the DMD process, different defects such as gas porosity, lack of fusion porosity, and adhesion occurred. Fortunately, no crack was observed, and the minimum porosity was about 0.09%.