Effect of Laser Powder Bed Fusion Parameters and Hot Isostatic Pressing on the Microstructure and Mechanical Properties of C22 Alloy

This study investigates the effect of Laser Powder Bed Fusion (LPBF) parameters and Hot Isostatic Pressing (HIP) on the microstructure and mechanical properties of Hastelloy C22 alloy. The primary objective was to optimize laser power and scanning speed to achieve the highest density in the manufactured specimens, with optimal conditions identified at 150 W and 200 mm/s, yielding a relative density of 99.6%. A total of eight post-processing conditions including heat treatment and HIP were evaluated to analyze phase composition and microstructural characteristics using various microscopy techniques. The results revealed that typical cellular and columnar dendritic structures were present in as-printed samples, with Mo-rich nanoparticles enhancing strength. While HIP was effective in reducing defects, fine precipitates were observed in the HIPped samples. Solution heat treatment resulted in complete recrystallization but demonstrated limited impact on mechanical enhancement compared to HIP. Consequently, the findings suggest that LPBF followed by HIP is essential for producing fully dense parts with optimal mechanical properties, while the role of solution treatment is comparatively less significant.