Uncovering hidden bias in neutron diffraction residual strain measurements

What is it about?

A method is described for identifying biased residual strain measurements and correcting their associated uncertainty intervals. In this case, the diffraction measurements are biased due to small scale sample heterogeneity, common to additive manufacturing.

Featured Image

Why is it important?

For the qualification of structural components, particularly those produced by solid-state or other additive manufacturing process, it is imperative to assess the impact of macroscopic residual strain on part performance and its associated uncertainty with respect to safety factors. Solid-state additive manufacturing promises to supplement unstable supply chains by producing big parts that would have had large lead-times. However, residual stress evolution is a major crux that must be solved. First it must be appropriately understood and calculated. Many researchers and industrialists believe that there is little to no residual stress in these components, an assumption that is based on erroneous interpretation of diffraction data. However, these parts tear themselves apart during the manufacturing process, thus it cannot be ignored.