Analysis of Microstructure and Defects of FGH96 Superalloy Manufactured by Laser Rapid Prototyping

The microstructures of the as-deposited and solution-aging of the laser rapid prototyping (LRP) FGH96 superalloy were observed by using optical microscopy (OM) and scanning electron microscopy (SEM). The character and formation reason of the microstructure and defects of the two samples were also analyzed. Room temperature tension tests were conducted in order to compare the mechanical property of the two condition samples. The rupture characters were analyzed based on the observation of the fractures by using OM and SEM. The results indicate that the main structure of the as-deposited FGH96 is typical directional solidification columnar structure which is perpendicular to the melting interface. The fine dendrite exists within the columnar grain, and the carbides segregate in the interdendrite. The dendrites become coarse in the re-melting region, displaying a bright white color. After solution-aging, the carbides decrease and the microstructure is more homogenous. The main defects of the LRP FGH96 are intergranular cracks, both in the as-deposited and solution-aging samples. The mechanical property of the sample after solution-aging has improved with the as-deposited one.