A comparison of the microstructures and mechanical properties of a GH648 superalloy fabricated by selective laser melting and casting

The microstructures and mechanical properties of a high-Cr contained GH648 superalloy, manufactured by selective laser melting (SLM) or casting, and then experiencing solution and ageing (SA) heat treatments, were investigated systematically. The SLMed-SA samples have an average grain size of 63.8 ?m, which is far finer than that of the casting-SA samples. The casting-SA and SLMed-SA GH648 superalloys have a similar phase constitution, including ?-Cr primary phase, acicular ?-Cr precipitates, and carbides, except that the ?? phase can be obviously detected in the SLMed-SA alloy, instead of the casting-SA alloy. The sizes of these phases in the SLMedSA alloy are much finer than those in the casting-SA alloy. Tensile tests indicate that the SLMed-SA samples have much higher strength than the casting-SA samples, due to the smaller size in the carbides, ?-Cr precipitates and grain, and the increased number of the precipitates in the SLMed-SA samples.

Automated summary

The microstructures and mechanical properties of high-Cr GH648 superalloy fabricated by selective laser melting (SLM) or casting were systematically studied after solution and aging (SA) heat treatments. It was found that SLMed-SA samples exhibited finer grain size, smaller carbides, α-Cr precipitates, and higher strength compared to casting-SA samples, primarily due to the increased number of precipitates in the SLMed-SA samples.