Protocol for lab-scale and large-scale x-ray quantification of retained austenite in AM steels

Purpose and goal

This project aimed at increasing our understanding of, and ability to measure, austenite phase fractions in AM steels. Characteristic for AM materials is a strongly textured structure with long directional grains as a result of epitaxial solidification. This makes characterization studies of printed microstructures challenging and standardized methods developed for conventionally manufactured materials cannot always be used. The goal of this project was to develop a protocol for measurement of retained austenite in tool steels using synchrotron x-ray diffraction.

Expected results and effects

The measurement results from the measurements at CHESS (Cornel high energy synchrotron source) led to the conclusion that, to be able to measure the austenite amount, the measurements need to be conducted in both building direction since some of the steel give different amounts for the different directions. It could also be concluded that the austenite fraction varies depending on how far from the build platform the measurement is performed.

Planned approach and implementation

The project was divided into three parts. During the first part, the beamtime and what materials to select for the measurement was planned in collaboration with the industrial partner. During the second part of the project, the measurements were conducted and the data was analyzed. The third part of the project focused on the dissemination of the results. A manuscript for publication is in preparation.