Microstructural Information Mapping of a Plastic-deformed α-iron Plate during Tensile Tests using Pulsed Neutron Transmission

The spatial-dependent lattice spacing and microstructure of an α-iron plate with two notches was measured during tensile tests using a pulsed neutron transmission method to ascertain changes depending on the load. Changes in microstructural parameters such as macrostrain, microstrain, crystallite size and texture are interesting during the transition from the elastic to plastic deformation region, especially over a relatively wide field of view to see propagation of the change. The method has the capability to show changes in the position-dependence of microstructural information simultaneously over a wide area in the bulk material. Transmission spectra around the Bragg-edge regions of the neutron total cross section of α-iron were obtained, and the microstructural parameters, {110} plane spacing and its distribution, texture coefficient and crystallite size were analyzed. The spatial-dependent distributions (images) of these parameters show sample shape effects including strain concentration around the notches and the effect of dislocations being multiplied during the plastic deformation. The spatial dependence of the microstructural parameters visualized herein provides useful information for evaluating the inhomogeneous progress of deformation of the bulk engineering material.