Abstract：The GH4099 alloy samples with different compositions were printed using selective laser melting
manufacture, the influence of different alloy compositions on the microstructure and mechanical properties was
investigated. The results showed that there were no obvious defects in the as-printed microstructure of the three
component GH4099 alloy, but there were differences in the degree of equiaxation of the columnar grains after
solution heat treatment, mainly due to differences in the carbides formation elements such as C, Cr, Mo, W, and
Ti, which led to different characteristics of carbides in GH4099 alloy. The tensile strength and plasticity of
GH4099 alloy at 900 ℃ have significant differences among different compositions, which are significantly relat‐
ed to the degree of equiaxation and the distribution position and morphology of carbides in the microstructure of
each alloy. The discontinuous distribution of carbides at equiaxed grain boundaries and the dispersed distribution
of fine M
23C6 type carbides within grains are beneficial for maintaining high strength and plasticity. The high content of MC type carbides in the initial microstructure is continuously distributed along the grain boundaries,
and pinning the grain boundaries results in a lower degree of equiaxation of the columnar grains, exhibiting high
strength and low plasticity. The fracture morphology shows fracture along the original columnar grain boundar‐
ies. Ti and other elements that promote the formation of MC type carbides are not beneficial to grain equiax‐
ation and detrimental to tensile plasticity at 900 ℃ attributed for the continuously distributed MC type carbides
along grain boundaries. Cr, Mo, W and other elements that promote the formation of M23C6 type carbides have
an impact on grain equiaxation, but can improve high-temperature strength through solid solution strengthening
and maintain good plasticity at 900 ℃.
2023, Vol. 33 
