Welding-induced microstructure in austenitic stainless steels before and after neutron irradiation

The effects of neutron irradiation on the microstructure of welded joints made of austenitic stainless steels have been investigated. The materials were welded AISI 304 and AISI 347, so-called test weld materials, and irradiated with neutrons at 300 degrees C to 0.3 and 1.0 dpa. In addition, an AISI 304 type from a decommissioned pressurised water reactor, so-called in-service material, which had accumulated a maximum dose of 0.35 dpa at about 300 degrees C, was investigated. The microstructure of heat-affected zones and base materials was analysed before and after irradiation, using transmission electron microscopy. Neutron diffraction was performed for internal stress measurements. It was found that the heat-affected zone contains, relative to the base material, a higher dislocation density, which relates well to a higher residual stress level and, after irradiation, a higher irradiation-induced defect density. In both materials, the irradiation-induced defects are of the same type, consisting in black dots and Frank dislocation loops. Careful analysis of the irradiation-induced defect contrast was performed and it is explained why no stacking fault tetrahedra could be identified. (c) 2006 Elsevier B.V. All rights reserved

Mechanical properties-micro structure correlation in neutron irradiated heat-affected zones of austenitic stainless steels

The effects of neutron irradiation on austenitic stainless steels, usually used for the manufacturing of internal elements of nuclear reactors (e.g. the core shrouds), are the alteration of the microstructure, and, as a consequence, of the mechanical properties. The present study is aimed at extending knowledge upon the impact of neutron-irradiation on the heat-affected zone of welded materials, which was influenced by the thermal cycles upon fusion welding. An austenitic stainless steel weld type AISI 304 from a decommissioned experimental pressurised water reactor has been used in the present study. The welded material has been irradiated during 11 reactor cycles to a maximum dpa dose of 0.35 and a temperature of around 573 K. The mechanical properties and microstructure are determined on specimens from heat-affected zone and base materials, with different dose levels. The mechanical properties were determined by performing tensile tests on small flat specimens at two deformation temperatures: room temperature and about 573 K. The characterisation of the microstructure was made by transmission electron microscopy. The correlation between mechanical properties and microstruclure after neutron irradiation is made using the dispersed obstacle hardening model. It was found that the measured radiation hardening cannot be explained solely by the presence of the irradiation-induced defects observed in TEM. Smaller irradiation-induced features not resolvable in TEM may also contribute to radiation hardening. (C) 2007 Elsevier B.V. All rights reserved

THE IMPACT OF ORIGIN ON CREATING A CULT BRAND: THE CASE OF APPLE

This paper introduces the concept of a cult brand for a more accurate understanding of the extreme loyalty that consumers show towards specific brands. The article focuses on the brand Apple and it explores the elements for which it is considered a cult brand and the impact of its origin on sustaining its cult appeal. Based on the fact that many brands rely on emotional characteristics to obtain consumers’ interest and attention, the country responsible for their conception is usually a warranty for quality and respect, features transferred to consumers. Through an exploratory research, based on investigation of secondary information as a data collection method, the research focuses on Apple's corporate mythology, its brand name, its geographical provenance and also the community surrounding it. The results of the study revealed that brand origin had a major role in creating the image that Apple sustained in the last decades, the conclusion reinforced the idea that on a solid foundation can be built a complex structure