Understanding Metal Powders in Additive Manufacturing — Part 1: Chemical composition

Welcome to the next installment of our comprehensive series exploring the complex world of metal powders for additive manufacturing (AM). As part of this series, inspired by our foundational article “Understanding Metal Powders in Additive Manufacturing”, we continue our journey into the world of powder properties that are critical to AM processes. The powder is the foundation of the AM process, determining its efficiency, quality and profitability.

Chemical composition: A fundamental characteristic

In this article, we focus on one fundamental aspect: the chemical composition and purity in terms of elements such as oxygen.

The chemical composition of the powder must comply with the standard specifications of the material. It is possible that the chemical composition changes during the powder production process. Evaporation of elements is possible. For this reason, the lower limits of some elements in AM powders are sometimes slightly higher than the material standard.
For some AM powders, there are generally certain limits for undesirable interstitial elements (O, N, H, C), as these can have a negative influence on the component properties. Powders that have a strict requirement for these limits are usually produced using the Vacuum Induction Melting Gas Atomization (VIGA) process, as the contents can be metallurgically minimized under vacuum. If you like to learn more about powder production have a look to our article “Metal powder production of non-reactive materials”. For example, the limit values for oxygen for Inconel materials are in the range of < 300 ppm. In addition to being incorporated in an oxide layer, oxygen can also be dissolved in the material. Excessive oxygen content can lead to a deterioration in mechanical properties. The chemical composition of the powder is determined using various methods.