Microscopic defects that typically occur in laser-based manufacturing of metal parts can lead to some serious issues down the road if left undetected. Fixing these mistakes can lead to a significant cost and time increase when producing a part. Although, new research into what causes these flaws may have led to a remedy for the problem.
Researchers from Missouri S&T, Argonne National Laboratory and the University of Utah have developed high-speed x-ray movies of a manufacturing circumstance known as laser spattering. This refers to the ejection of molten metal from a pool heated by a high powered laser during laser-based manufacturing processes, such as welding and additive manufacturing. Various industries use these types of manufacturing processes to develop their parts such as aerospace, automotive, healthcare, and construction.
The researchers have published their findings in the journal, Physical Review X, in a paper titled Focus: X-Ray Movie Reveals Origin of Metal Splashing.
Utilizing the power of x-ray imaging, the researchers captured the spattering behavior of a titanium alloy known as Ti-6AI-4V during its fabrication process. These microscopic movies made by the researchers have revealed: “a novel mechanism of laser spattering—the bulk explosion of a tongue-like protrusion” that appears in one area of the metal.
“The newly discovered mechanism will guide the development of approaches to mitigate defect formation in welds and additively manufactured parts,” says Dr. Lianyi Chen, assistant professor of mechanical and aerospace engineering at Missouri S&T.
Chen worked together with Dr. Tao Sun’s team at Argonne National Laboratory and Dr. Wenda Tan’s team at the University of Utah. The teams were able to create the images with the help of a high energy synchrotron x-ray at the Argonne National Laboratory along with image analysis and numerical simulations.
“The high penetration power of hard X-rays and high resolution of the imaging technique enable us, for the first time ever, to connect the spattering behavior above the surface with dynamics below the surface and inside the titanium sample,” Chen says.