In great scientific progress, researchers from the Argonne National Laboratory of the US Ministry of Energy, the National Laboratory of Oak Ridge and other universities have observed how the microstructure of metals changes in real time during 3D printing. This breakthrough was made possible by Argonne's Advanced Photon Source (APS), a Doe -Office of Science User Facility. The results were published in Nature Communications.
Before that, scientists could only analyze the microstructures of 3D printed components after completing the printing process.
“Metals consist of atoms that are arranged in orderly crystal structures,” said Tao Sun, the leading investigator of the project and professor at Northwestern University, who also has a common appointment at Argonne. “But under fast heating and cooling, some atoms fall from the alignment. These defects – referred to as transfers – can strengthen or weaken the final part.”
Using Beamline 1-ID-E at the APS, the team 3D printing of 316l stainless steel carried out, a frequently used structural alloy. They pursued the printing process with real-time X-rays and measured directly on how and when transfers form and spread.
“Our analysis shows how powerful the APS are for the examination of defects that were previously only seen by after the fact analysis,” said Andrew Chuang, physicist at APS. “This is the first time that this real-time technique was applied to this laser-based method to examine the transfer development in a metal wire.”
The data showed that transfers formed at an early stage, as the metal changes from liquid to solid. It was previously assumed that they will form later when stress is built up while cooling and strengthening. A key factor was a specific reaction in which two fixed phases form from the liquid at the same time and create a high density of transfers.
This deeper understanding could help engineers to improve the strength and reliability of 3D printed parts. By adapting print variables, developers could precisely control the formation of transfers at the microscopic level. In this way, you could fully exploit the advantageous attributes of the transfers and at the same time minimize the harmful minimizing.
The knowledge gained could also stimulate the development of new alloys. The adaptation of the chemical make -up of rustproof steels – for example by changing the conditions of chrome or nickel or by adding elements such as aluminum – can influence the formation of failure and how stress is distributed.
“This type of 3D printing could create tailor-made metal parts that are reliable and extremely strong and would survive extreme conditions,” said Lin Gao, a post-doctoral researcher in the Nuclear Science and Engineering division at Argonne. “It can be the key to the construction of advanced metal components for the next generation nuclear reactors that are now being developed at Argonne and other laboratories.”