119 research outputs found
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Morphology and Grain Texture in As-Deposited and Heat Treated Inconel 718 Structures Produced using Laser-Based Powder Bed Fusion
With increasing interest in the use of powder bed fusion (PBF) processes for additive
manufacturing, understanding the relationship between as-deposited and heat treated states and
the intrinsic anisotropy of fabricated parts has become critical for its successful application. This
phenomenon has been studied and reported extensively for Inconel 718 parts fabricated using
PBF for aerospace applications, but few reports exist on the morphology and grain texture of
Inconel 718 parts fabricated for oil and gas applications, which have different demands. This
work demonstrates that the anisotropy in Inconel 718 parts produced using laser-based PBF is
not entirely removed by subsequent heat treatments, and it may be an artifact of the as-deposited
grain structure, whose elongated grains may stretch through several melt pools. The as-built
material is observed to exhibit some texturing, with (001) being the preferential growth direction.
Despite some residual anisotropy, heat treatments are sufficient to provide material qualities that
meet specification, even without the use of a HIP (hot isostatic pressing) step. It is hypothesized
that similarly elongated grain structures may explain the anisotropy observed in other materials
systems employed in PBF additive manufacturing processes.Mechanical Engineerin
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A Preliminary Examination of Variability Due to Build Location and Powder Feedstock in Additive Manufacture of Inconel 718 using Laser-Based Powder Bed Fusion
The production of metallic parts by additive manufacturing (AM) is of significant interest
to industry, but in the absence of standards, practical design considerations for manufacturing
engineers are not widely known. Within the context of powder bed fusion (PBF), many
unknowns persist regarding variations in part quality due to part location on the build plate,
process consistency, feedstock supplier, and machine manufacturer. In this paper, we investigate
the mechanical property variance across the build platform and document the successful use of
feedstock powders obtained from several suppliers for the manufacture of Inconel 718 tensile
and Charpy specimens, built on an EOS M280 laser-based powder bed fusion system. Particular
emphasis is placed on describing the manufacturing process design challenges encountered even
for simple geometries. While many advocate that complexity is free when using AM, we find
that AM can lead to expensive build failures given the current state of manufacturing process
knowledge and that design for additive manufacture is required for successful application of AM
techniques.Mechanical Engineerin
Patterns and universals of mate poaching across 53 nations : the effects of sex, culture, and personality on romantically attracting another person’s partner
As part of the International Sexuality Description Project, 16,954 participants from 53 nations were administered an anonymous survey about experiences with romantic attraction. Mate poaching--romantically attracting someone who is already in a relationship--was most common in Southern Europe, South America, Western Europe, and Eastern Europe and was relatively infrequent in Africa, South/Southeast Asia, and East Asia. Evolutionary and social-role hypotheses received empirical support. Men were more likely than women to report having made and succumbed to short-term poaching across all regions, but differences between men and women were often smaller in more gender-egalitarian regions. People who try to steal another's mate possess similar personality traits across all regions, as do those who frequently receive and succumb to the poaching attempts by others. The authors conclude that human mate-poaching experiences are universally linked to sex, culture, and the robust influence of personal dispositions.peer-reviewe
Are men universally more dismissing than women? Gender differences in romantic attachment across 62 cultural regions
The authors thank Susan Sprecher (USA), Del
Paulhus (Canada), Glenn D. Wilson (England), Qazi
Rahman (England), Alois Angleitner (Germany),
Angelika Hofhansl (Austria), Tamio Imagawa
(Japan), Minoru Wada (Japan), Junichi Taniguchi
(Japan), and Yuji Kanemasa (Japan) for helping with
data collection and contributing significantly to the
samples used in this study.Gender differences in the dismissing form of adult romantic attachment were investigated as part of the International Sexuality Description Project—a survey study of 17,804 people from 62 cultural regions. Contrary to research findings previously reported in Western cultures, we found that men were not significantly more dismissing than women across all cultural regions. Gender differences in dismissing romantic attachment were evident in most cultures, but were typically only small to moderate in magnitude. Looking across cultures, the degree of gender differentiation in dismissing romantic attachment was predictably associated with sociocultural indicators. Generally, these associations supported evolutionary theories of romantic attachment, with smaller gender differences evident in cultures with high–stress and high–fertility reproductive environments. Social role theories of human sexuality received less support in that more progressive sex–role ideologies and national gender equity indexes were not cross–culturally linked as expected to smaller gender differences in dismissing romantic attachment.peer-reviewe
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