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CARATTERIZZAZIONE DI ACCIAI INOSSIDABILI BIFASICI GRADO F55 CON TENORI DI NICHEL DIVERSI
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High-temperature mechanical properties of P91 weld metal
No full textIncreasing temperature is one of the key factors for improving the efficiency of steam power plants. Important metallurgical phenomena are activated at such high temperatures and creep resistance becomes a driving criterion for the material selection. Ferritic steels, including 2Cr, 9Cr, and 12Cr steels, are among the best candidates; their continuous development and optimization with the addition of Mo, V, Nb, and W have resulted in a significant improvement in creep strength together with a good weldability. This study investigates the high-temperature mechanical properties of two Grade 91 welded plates and focuses on the creep behavior, proposing a modified expression of the Larson-Miller parameter for the estimation of critical combinations of temperature, stress, and time, which could lead to rupture. The suggested parameter, which is highly sensitive to temperature, is able to outline the criticality of the welding and it is useful for predicting the duration of a creep test with the specimen rupture
Mechanical and Microstructural Characterization of Forged Inconel 625 Ring Gaskets for Oil and Gas Application
No full textThe spinodal decomposition of ferrite in 2507 biphasic stainless steels: embrittlement and possible toughness recovery
Full text linkBiphasic stainless steels provide an excellent combination of mechanical and corrosion properties. The occurrence of ferrite spinodal decomposition during processing and heat treatment can induce a dramatic drop in impact energy. In this paper, a forged rod of 480 mm diameter made of 2507 biphasic stainless steel was studied. The spinodal decomposition phenomenon upon aging at 475 degrees C (748 K) was investigated by macro- and micro-hardness tests on the constituent phases and by Charpy impact tests. Then, the influence of the microstructural constituents and their morphology on the crack path was studied by optical microscopy, noting possible correlations with the impact energy. Successively, the fracture surfaces of selected specimens were analyzed by a scanning electron microscope (SEM). Finally, reversion heat treatments at 550 degrees C (823 K) and 600 degrees C (873 K) were investigated to evaluate the possibility of recovering the detrimental effects of the alpha' embrittlement. According to the literature, this procedure works well with some biphasic steels, but these steels are characterized by a chromium content lower than that of 2507 grade steel. Regarding the 2507 grade steel studied in this work, complete reversion was obtained by solution-annealing treatment, while reversion heat treatments at both 600 degrees C (873 K) and 550 degrees C (823 K) allowed only a partial recovery
Going Beyond Counting First Authors in Author Co-citation Analysis
Full text linkThe present study examines one of the fundamental aspects of author co-citation analysis (ACA) - the way co-citation
counts are defined. Co-citation counting provides the data on which all subsequent statistical analyses and mappings
are based, and we compare ACA results based on two different types of co-citation counting - the traditional type that
only counts the first one among a cited work's authors on the one hand and a non-traditional type that takes into
account the first 5 authors of a cited work on the other hand. Results indicate that the picture produced through this non-traditional author co-citation counting contains more coherent author groups and is therefore considerably clearer. However, this picture represents fewer specialties in the research field being studied than that produced through the traditional first-author co-citation counting when the same number of top-ranked authors is selected and analyzed. Reasons for these effects are discussed
Variations on the Author
Full text link“Variations on the Author” discusses two of Eduardo Coutinho’s recent films (Um Dia na Vida, from 2010, and Últimas Conversas, posthumously released in 2015) and their contribution to the general question of documentary authorship. The director’s filmography is characterized by a consistent yet self-effacing form of authorial self-inscription: Coutinho often features as an interviewer that rather than express opinions propels discourses; an interviewer that is good at listening. This mode of self-inscription characterizes him as an author who is not expressive but who is nonetheless markedly present on the screen. In Um Dia na Vida, however, Coutinho is completely absent form the image, while Últimas Conversas, on the contrary, includes a confessional prologue that moves the director from the margins to the center of his films. This article examines the ways in which these works stand out in the filmography of a director who offers new insights into the notion of cinematic authorship
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