Scientists have developed a new method to create stronger metals for use in extreme environments such as power generation turbines. By using 3D printing and neutron technology to analyze the metal, they found that heat treatment can reduce stress within the metal, making it more durable.

Neutron experiments have revealed microscopic details of a special 3D printed superalloy that has the potential to reduce component costs. (The 3D printed metal sample is approximately 4 inches wide). The printed and heat-treated samples are mounted on a base and exposed to a neutron beam to analyze residual stresses or irregularities such as cracks or voids created during the manufacturing process). Source: Oak Ridge National Laboratory

Extreme applications such as advanced gas turbines used to generate electricity require equally sophisticated materials. In this study, scientists investigated the stress effects of an innovative "superalloy" composed of two high-strength, high-temperature-resistant metals. The team created these alloys using 3D printing technology, which uses lasers to shape metal powder into specific shapes. They then used neutrons to analyze the internal structure of the printed metal.

Research has found that heat treatment can effectively relieve stress generated during the manufacturing process. Furthermore, the study found that these stresses are more affected by specific manufacturing parameters than by the chemical composition of the metal.

The research team cleverly used laser-based 3D printing technology to create an alloy from two different metals (Inconel 718 and Rainey 41) without any cracks. Neutron experiments have led to the development of an enhanced method for accurately and efficiently assessing stress levels in metals throughout the manufacturing process. The findings will help produce stronger, more advanced alloys that are cheaper to manufacture. These alloys are critical for applications in extreme environments.

Additive manufacturing, or 3D printing, is a new method of manufacturing metal parts and other types of materials layer by layer. The research project, a collaboration between researchers at General Electric Company, the Edison Welding Institute, and Oak Ridge National Laboratory (ORNL), printed an alloy consisting of Inconel 718 and Raney 41 on both ends, with a compositionally graded area in the middle. The study evaluated stress and compositional changes in the alloy. To this end, researchers conducted neutron experiments at the Swelling Neutron Source (SNS) and the High Flux Isotope Reactor (HFIR) at ORNL, both DOE Office of Science user facilities. Neutrons are ideal for studying the internal stresses of materials because they can penetrate dense metals.

Using SNS's VULCAN diffractometer and HFIR's MARS imager, the researchers measured the distribution of residual lattice strain to understand how the material's residual stress and composition change during different processing stages. Neutron studies have shown that residual stresses are mainly caused by the manufacturing process and can be alleviated by heat treatment. Studies have found that the longer the laser dwell time or the higher the energy, the greater the stress. Neutron research has also helped the company establish a more efficient way to analyze metals, making them more useful for making better parts at lower costs using additive manufacturing.

Compiled from/SciTechDaily

DOI:10.3389/ftmal.2022.1070562