Effects of heat treatment on microstructures and mechanical properties of GH4169/K418 functionally graded material fabricated by laser melting deposition

Abstract

Blade-Integrated Disk is a perspective one-piece design strategy of turbine engine components with high efficiency of air compression. In this work, a functionally graded material composed of GH4169 and K418 is processed by laser melting deposition technique, followed by suitable heat treatment to optimize the microstructures and mechanical properties. Microstructure characterization, tensile and small punch creep tests of the functionally graded GH4169/K418 specimens were conducted. It is found that the as-built functionally graded material exhibits the continuous microstructure and the gradual composition transition region without sharp interfaces and hot cracks. The tensile yield strength, ultimate strength and elongation of the graded specimens at fracture achieved 726 MPa, 1044 MPa and 13.2%, respectively after the specimens were heat-treated through homogenization at 1100 °C for 1.5 h, solution treatment at 980 °C for 1 h and standard double aging. The creep life of the GH4169/K418 graded specimens at 650 °C and 850 N was mainly affected by the microstructure formed at different build heights of the as-built and heat-treated specimens. The relationship between the microstructures and tensile as well as creep properties of the graded specimens is elucidated.