A New Residual Strain Mapping Program Using Energy Dispersive X-Ray Diffraction at the Advanced Photon Source

Background The ability to non-destructively map the residual strain field inside an engineering component is important for predicting its fatigue life or developing processing methods to prevent failure or enhance performance. Objective In this paper, we describe a new residual strain mapping program at the Advanced Photon Source, Argonne National Laboratory. Methods The new program is based on energy dispersive x-ray diffraction (EDXRD). It is capable of non-destructively penetrating a several-cm thick polycrystalline sample fabricated from engineering alloys using high-energy x-rays and measuring the residual strain field with mm or better spatial resolution and approximately ± 1 × 10^-4 strain resolution. A multi-element detector array is employed to measure multiple strain components simultaneously. The residual strain mapping setup is augmented with a high-energy tomography capability, allowing precise alignment of the material volume of interest for residual strain mapping and providing a complementary view of the structure to understand the measured strain field. Results These measurement capabilities are demonstrated using several strain mapping examples ranging from polycrystalline structural alloys to biological materials. We also provide some guidance for the future users of the program for a successful residual strain mapping experiment. Conclusions We are expanding the capabilities of the new setup with various in situ capabilities including thermo-mechanical loading.