Heat Treatment Effect on SLM Printed Al-Si12 Using Ultrasonically Atomized Powder

Additive manufacturing has evolved in recent years, gaining research interest from various industries. It became an important aspect of modern manufacturing since it enabled the production of the parts that were previously difficult to create. Laser-based additive manufacturing, such as selective laser melting (SLM), requires high-quality powder as feedstock. The properties of the powder can directly influence the quality of the printed part. Therefore, powder atomization has also gained attention in research society. Other than that, laser-based additive manufacturing involves high cooling rates that can result in residual stresses. Hence, stress relief heat treatment is required to avoid the warping of the part. However, heat treatment can significantly change the microstructure of the as-built part. Therefore, the quality and the final mechanical properties of the additively manufactured part are linked not only to the SLM parameters but also to the powder atomization and heat treatment. The influence of the printed part of both processes is still not fully understood. Hence, to study the effect of stress relief annealing on the additively manufactured material, the samples were tested on the tensile testing machine. For the printer feedstock material, Al-Si12 powder was produced on a laboratory scale using an ultrasonic atomizer. The produced powder was studied and observed under an SEM microscope. The morphology and particle size distribution were presented. The as-built samples from the atomized powder had tensile strength of 422 MPa. It was shown that heat treatment could significantly decrease the tensile strength, ultimate strain, toughness, and yield stress compared to the as-built samples.