Control of Anisotropic Texture for Improving Creep Property of Nickel Based Superalloy Fabricated by Metal Additive Manufacturing

Abstract

The demand for the improved efficiency of industrial gas turbine engines has led to the increase in turbine inlet temperature (TIT), and hence the operating environment temperature of turbine blades has been increasingly higher. For this reason, techniques to control anisotropic crystallographic texture have been developed such as directional solidification (DS) and single crystallization (SC), together with complex internal cooling designs for efficient metal cooling. However, with regard to precision casting methods for turbine blade production, it is difficult to achieve both high accuracy of complex internal shapes and anisotropic crystallographic texture. To overcome this challenge, we have focused on selective laser melting (SLM), a technique suitable for creating elaborate internal shapes. In addition, the material properties are greatly influenced by various factors such as fabricating conditions, including laser power, scanning speed, atmosphere during molding, etc., as well as alloy composition. Research on the microstructure control of additive manufacturing materials has been actively conducted in recent years, but no systematic study on the control of anisotropic crystallographic texture has been made. In this article, we demonstrate the control of anisotropic crystallographic texture using the IN718 nickel-based superalloy manufactured by SLM, and report the results on the improvement of creep properties.