Abstract
In this research, Wire arc additively manufactured IN625 alloy was subjected to different heat treatments and compared with the unheated alloy. All three samples were solution treated to a temperature of 980 °C followed by furnace cooling. S1 and S2 denote the solution-treated sample with a soaking period of 30 min and 1 hour respectively, whereas, S4 represents the sample which is aged for 8 hours at 720 °C respectively after the 1-hour solution treatment. The columnar and dendritic structures were visible in the parent additively manufactured (S1) specimen. These structures cannot be seen in the wire, which is used as the feed material for WAAM. The microstructure of the solution heat-treated specimen (S2) was seen with clear grain boundaries and precipitates. The micrograph confirms the uniform grain structure and more dispersed precipitates when compared to the unheated specimen. Though the average grain size remains the same, there were visible coarse grains in the 1-hour aged sample when compared to the 30-minute aged sample. The microhardness of the different heat-treated samples was measured using a Rockwell hardness tester to study the influence of heat treatment. The results revealed that the heat treatment significantly improved the hardness of the specimen.
