Microstructural characteristics and mechanical properties of laser solid formed K465 superalloy

K465 nickel-based superalloy is widely used in the manufacturing of hot section components of aeroengines such as turbine blades and guide blades due to its excellent high temperature strength and superior corrosion resistance. In the present work, K465 superalloy deposits are fabricated on 316 L stainless steel substrate by laser solid forming technique. The microstructure and tensile properties of the as-deposited samples are investigated. The results show that the as-deposited K465 samples mainly consist of columnar dendrites which grow epitaxially from the substrate and the dendrite are fine with the average primary dendrite arm spacing of 18 µm, only a few fine equiaxed grains appear at the top of the deposit. The γ′ particles in the deposit seem uniform in spherical shape and are much finer than that in the as-cast K465 samples. The average hardness of the as-deposited samples is measured as 468 HV, which is higher than that of the as-cast K465 sample. The tensile strength and the yield strength of the as-deposited samples are also high and measured to be 1205.4 MPa and 917.4 MPa, while their elongation is up to 8.5%.