Effects of Hot Isostatic Pressing (HIP) on microstructure and mechanical properties of K403 nickel-based superalloy

The microstructure of as-cast and as-HIPed (hot isostatic pressed) K403 superalloy was investigated using a scanning electron microscopy (SEM), as component analysis was conducted by energy dispersive x-ray spectrometer (EDS). It was found that the microstructure of the alloy was improved significantly through HIP. Firstly, the microporosity and micropores in as-cast alloy were ameliorated effectively and the morphology of grains tended to be uniform. Moreover, the morphology of carbides at grain boundaries transformed from thread-like to granular. Uppermost, the size, shape and volume fraction of γ′ phase were significantly optimized and γ′ precipitates in two different sizes were generated in matrix. Nanoindentation experiment was then carried out to obtain the nanohardness and elastic modulus of as-cast and as-HIPed K403 superalloy. The results revealed an obvious increase in both nanohardness and elastic modulus after HIP. Conclusions could be drawn from the research that HIP could improve the microstructure of as-cast K403 superalloy, which could enhance the mechanical properties of the alloy positively.