Numerical simulation on melt pool and solidification in the direct energy deposition process of GH3536 powder superalloy

Abstract

Rapid melting, solidification, and a highly powerful laser all contribute to complex heat transfer and flow phenomena during the directed energy deposition (DED) process. To investigate the impact of process parameters on the melt pool and solidification quality during the DED process, a three-dimensional finite element model (FEM) was established. The heat transfer, fluid flow, and solidification during the DED process were investigated. The correct input parameters for GH3536 superalloy were discovered by examining the effects of laser power, scanning speed, and feed rate on the shape of molten pool and interlayer fusion. To forecast the quality of the solidified structure at the cut-off point, temperature gradient and solidification rate discovered in transient thermal distribution were employed. The results shows that the melt pool will grow as a result of high laser power and low scanning speed or feed rate. Concentrating on the expansion of the melt pool is not the best solution because well-solidified microstructure frequently develops in the middle of the parameter set. The correlation between feed rate and laser power is insensitive. At a specific feed rate, the minimum threshold for scanning speed was discovered. When the scanning rate falls below the threshold, uneven solidification structures and anomalous melt pool morphology will take place. The undesirable and potentially fluctuating parameters were indicated, and the laser power and scanning speed range suited for the GH3536 superalloy were summarized. For the feed rate, the center of the parameter set is advised.

Keywords

• Directed energy deposition
• Melt pool
• Solidification
• GH3536
• Finite element method