Study of Fusion Boundary Microstructure and Local Mismatch of SA508/Alloy 52 Dissimilar Metal Weld with Buttering

Funding Information: The authors wish to express their gratitude for the funding and support from Ringhals AB, OKG AB, Teollisuuden Voima Oyj and VTT Technical Research centre of Finland within the FEMMA (Forum for the Effect of Thermal Ageing and Microstructure on Mechanical and EAC Behavior of Ni-based Alloy Dissimilar Metal Welds) research project. The authors also thank NKS for funding the NKS-FEMMA (AFT/NKS-R(22)134/4) project. The authors would like to thank P. Arffman, J. Lydman, A. Nurmela and L. Sirkiä for the experimental contributions. The authors would like to thank U. Ehrnstén, B. Forssgren, H. Reinvall and H. Hänninen for suggestions and discussions. Publisher Copyright: © 2023 The Author(s)A SA508/Alloy 52 dissimilar metal weld (DMW) mock-up with double-sided Alloy 52 butterings, which is fully representative of Ringhals pressurizer surge nozzle DMW repair solution, was studied. The microstructure, crystal structure, elemental diffusion, carbide formation and macro-, micro- and nano-hardness of the SA508/nickel-base Alloy 52 buttering fusion boundary (FB) were investigated. Three types of FBs were analyzed, i.e., narrow FB (∼80–85% of whole FB), tempered martensitic transition region (∼15%) and wide partially mixed zone (∼1–2%). The different FB types were induced by the local heat flow and respective elementary diffusion, which significantly influence the local hardness mismatch across the DMW interface and the local brittle fracture behavior.Peer reviewe

Mechanical behavior of high-Ni/high-Mn Barsebäck 2 reactor pressure vessel welds after 28 years of operation

To assess long-term operation of the reactor pressure vessel (RPV), surveillance programs are applied for periodic monitoring and prediction of the aging of the mechanical properties due to irradiation and thermal embrittlement. In literature, there are limited data sets to compare the results from the surveillance program to the aging of the RPV. In this work, the tensile and impact toughness properties of the high-Ni, high-Mn welds from decommissioned Barsebäck 2 RPV are characterized. The results indicate that the surveillance program describes sufficiently the aging of the RPV welds. Differences in mechanical properties of the welds from various regions are explained by variations in post-weld heat treatment. The synergetic effect of Ni and Mn on embrittlement appears not to result at low fluences in a significant difference in the embrittlement rate when compared to ASTM E900 embrittlement trend curve prediction

Materials Science and Technology - Nuclear Materials, Advanced Course - Kon-67.5100 Postgraduate Seminar on Engineering Materials - Seminar papers 8 October, 2015

The Engineering materials research group of Department of Engineering Design and Production of Aalto University arranged a postgraduate course on nuclear materials. The course consisted of three day long lecture session given in April 20-22, 2015. Lectures were given by professionals from nuclear power related research institutes (Aalto and VTT), nuclear industry and authority. The course also included a seminar session held October 8, 2015. The seminar session was targeted to postgraduate students, who prepared articles from their field of expertise. This proceeding is the collection of these seminar articles

Defective Secretion of Islet Hormones in Chromogranin-B Deficient Mice

Granins are major constituents of dense-core secretory granules in neuroendocrine cells, but their function is still a matter of debate. Work in cell lines has suggested that the most abundant and ubiquitously expressed granins, chromogranin A and B (CgA and CgB), are involved in granulogenesis and protein sorting. Here we report the generation and characterization of mice lacking chromogranin B (CgB-ko), which were viable and fertile. Unlike neuroendocrine tissues, pancreatic islets of these animals lacked compensatory changes in other granins and were therefore analyzed in detail. Stimulated secretion of insulin, glucagon and somatostatin was reduced in CgB-ko islets, in parallel with somewhat impaired glucose clearance and reduced insulin release, but normal insulin sensitivity in vivo. CgB-ko islets lacked specifically the rapid initial phase of stimulated secretion, had elevated basal insulin release, and stored and released twice as much proinsulin as wildtype (wt) islets. Stimulated release of glucagon and somatostatin was reduced as well. Surprisingly, biogenesis, morphology and function of insulin granules were normal, and no differences were found with regard to β-cell stimulus-secretion coupling. We conclude that CgB is not required for normal insulin granule biogenesis or maintenance in vivo, but is essential for adequate secretion of islet hormones. Consequentially CgB-ko animals display some, but not all, hallmarks of human type-2 diabetes. However, the molecular mechanisms underlying this defect remain to be determined

Global wealth disparities drive adherence to COVID-safe pathways in head and neck cancer surgery

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