Effect of Neutron and Electron Irradiation on Low Manganese Steels

Abstract

SynopsisThe interaction between solute atoms and radiation induced defects was studied by means of tensile test and transmission electron microscopy. The defects were produced by neutron irradiation at 473 K to a fluence of 6.4 x 1022 of m2 (E n> 1 MeV) and electron irradiation at 650 kV electron microscope to a fluence of 7 x 1025 of m2.Radiation hardening and radiation embrittlement occurred by neutron irradiation. The yield stress increased and the total elongation decreased with the increase of manganese content. Dislocation loops were observed in the i ron but not detected in manganese alloys. Therefore, it will be considered that the defects would be trapped by manganese atoms and then formed complexes with carbon. Defects produced by electron irradiation were not observed by electron microscopy in the manganese alloys, however, after annealing above 598 K the defect clusters, presumably interstitial type, appeared and grew. The annealing behaviors were similar for both the neutron and electron irradiated specimens.The radiation hardening could be explained by the mechanism in which manganese atoms trap carbon and interstitial atoms during irradiation and then form fine complexes, which would act as the obstacles for dislocation motion.

Simulation of the nanostructure evolution under irradiation in Fe–C alloys

“…The reference experimental data are denoted with triangles [4]. Included in the graph are also data from other comparable irradiation experiments in Fe-C (bullets) [9,8,10,11,12,13]. See [6] for full details.…”

“…To get a more complete picture from the available experimental data in α-Fe, we have also considered other experiments, with less complete data: [9,10,11,12,13]. A more thorough overview of the available irradiation and annealing experiments with pure Fe will be published in a separate paper [6].…”

MD modeling of defects in Fe and their interactions

“…(5). The computed value of a suggests a higher obstacle strength for h1 0 0i loops than other calculations quoted in the literature [22,39]. Of course, N and d have been obtained directly from our computation box and are subject to the narrow applicability window of this MD simulation.…”

Neutron irradiation hardening and microstructure changes in Fe–Mn binary alloys

“…Although it is difficult to reveal the nature of point defect clusters less than 1 nm by transmission electron microscopy (TEM), vacancy clusters can be pursued by positron annihilation spectroscopy (PAS). However, only a few studies have reported the irradiation hardening and microstructure changes in Fe-Mn alloys [14,15]. Furthermore, the irradiation dose that the materials used in previous studies were subjected to was so low that the effect of Mn probably could not form a sufficient number of point defect clusters.…”