Influence of Build Orientation on Surface Roughness and Fatigue Life of the Al2024-RAM2 Alloy Produced by Laser Powder Bed Fusion (L-PBF)

Abstract

Additive manufacturing of high strength Al alloys brings problems with hot cracking during rapid solidification. One of the ways to solve this challenge is technology developed by the Elementum 3D company. The way consists of inoculation by ceramic nanoparticles using RAM technology. When applying the L-PBF method, a very fine equiaxed microstructure with exceptional properties and without cracks is created. This paper offers the results and discussion of the microstructure, surface roughness and fatigue life of the high-strength Al2024-RAM2 alloy made from a gas atomized powder with an additive of 2 wt.% ceramic nanoparticles on the base of Ti. The specimens for fatigue tests were produced in different orientations relative to the building platform and left in the as-built conditions with different surface quality (roughness). The specimens were T6 heat-treated. The treatment caused a coarsening of a part of the fine grains. After T6 heat treatment, the hardness increased significantly, which occurred by precipitation hardening. Fatigue tests of specimens with different build orientation were performed in plane bending and the experimentally determined fatigue life was discussed in terms of surface roughness and material microstructure.