Effect of Different Scanning Modes and Heat Treatment on Microstructure and Mechanical Properties of GH4169 Manufactured by Selective Laser Melting

Abstract

GH4169 superalloy was prepared by selective laser melting technique. The samples were obtained by scanning in a single direction per layer and scanning in a 90° direction per layer, respectively. The microstructure and precipitated phase were compared and analyzed by OM, SEM and EDS to investigate the non-equilibrium microstructure characteristics and the influence mechanism on mechanical properties of laser additive manufacturing materials of GH4169 under three heat treatment systems. The results show that in the X direction of laser scanning deposition, the tensile strength at room temperature of the material with the same scanning direction of each layer is 4.5% higher than that of the material with the scanning direction of 90°, and the reduction of area is 75.6% higher. After solution and aging treatment, δ phase was precipitated and Laves phase was partially dissolved, but the element segregation in the remelting zone between the cladding layers was not completely eliminated. Homogenization treatment at 1050 ℃ for 1h promotes uniform distribution of segregation elements in cladding layer, remelting layer and dendrite. After homogenization treatment at 1100 ℃ for 1h, Laves phase was fully redissolved, and δ phase and strengthening phase γ ‘ were precipitated again after solution and aging. After heat treatment, the tensile strength at room temperature of the samples prepared by the two laser scanning methods is basically the same in the X direction.