Effect of Inclination Angle on Microstructural Evolution and Mechanical Property of Support-Free IN718 Alloy Fabricated by Selective Laser Melting

Abstract

Selective laser melting (SLM) process without support is crucial for fabricating complex components of superalloy at some conditions. To realize that, it is indispensable to uncover the effects of inclination angles on microstructural evolution and mechanical property. In this research, the microstructure and mechanical properties of IN718 superalloy samples fabricated by SLM under different inclination angles of 40°, 50°, 60°, 70°, 80° and 90°were investigated. The results show that the relative densities of the SLM-ed alloy rise with the increase of the inclination angle. Improved densities and surface smoothness are achieved when the inclination angle exceeds 60°. As the inclination angle changes from 40° to 90°, the texture is transformed from < 111>∥width direction (WD) to < 111>∥length direction (LD), and the content of columnar and V-shaped grains is increased correspondingly. The alteration in inclination angle induces the shift in the heat flow direction, therefore influencing the epitaxial growth of grains. Thereafter, textures and the angles between tensile direction and building direction have significant effects on the strength of the alloy. The alloy built at 40° exhibits a maximum yield strength of 742.4 MPa, and the yield strength decreases to 715.9 MPa when the inclination angle elevates to 90°.

Graphical Abstract