Texture analysis implementation at the neutron strain diffractometer POLDI

Neutron strain scanners have been proven to be a key tool to non-destructively determine the crystallographic texture at selected locations within a macroscopic object. In particular, time-of-flight neutron strain scanners present the advantage that several crystalline reflections can be measured simultaneously for a given specimen direction, allowing the determination of several (incomplete) pole figures from a single experimental arrangement. Here we will present the implementation of a novel data analysis methodology to perform spatially resolved texture analyses in bulk specimens at POLDI, the Pulse Frame Overlap diffractometer at Paul Scherrer Institute. The method is based on the determination of several incomplete pole figures after splitting POLDI's diffraction detector, with an angular range of 30°, into several units of smaller angular coverage. This is done by time-focusing the neutrons arriving at all the detection elements of the new ‘virtual detector’ into a single diffractogram, performing a 2D-least squares fitting of the diffraction data and creating experimental pole figures from the Euler angles of the explored sample orientations and the refined peak areas corrected by the flight path of the neutrons inside the sample. From the incomplete experimental pole figures, the determination of the orientation distribution function of crystallites is accomplished using the MTEX toolbox. We will present demonstration experiments on a stainless steel additive manufacturing specimen and a hot-rolled and annealed Zircaloy-4 plate. • Non-destructive spatially resolved crystallographic texture methodology at POLDI. • POLTex: a crystallographic texture analysis toolbox for POLDI. • Texture characterization of engineering specimens.