Synergetic strengthening of layered steel sheet investigated using an in situ neutron diffraction tensile test

Synergetic strengthening induced by plastic strain incompatibility at the interface, and the resulting extra geometrically necessary dislocations (GNDs) generated during plastic deformation, were investigated to understand the origin of extra strength in heterogeneous structured (HS) materials. The mechanism of extra GND generation in twinning-induced plasticity (TWIP)-interstitial free (IF) steel layered sheet was quantitatively analyzed by conducting in situ neutron scattering tensile test. Load partitioning due to the different mechanical properties between the TWIP-steel core and IF-steel sheath at the TWIP/IF interface was observed during the in situ tensile testing. Because of the plastic strain incompatibility from load partitioning, extra GNDs are generated and saturate during tensile deformation. The extra GNDs can be correlated with the back-stress evolution of the HS materials, which contributes to the strength of layered materials. Because of the back-stress evolution caused by load partitioning, the strength of TWIP-IF layered steel is higher than the strength estimated by the rule-of-mixtures. This finding offers a mechanism by which extra GNDs are generated during load partitioning and shows how they contribute to the mechanical properties of HS materials.11Ysciescopu

The Mildly Elevated Serum Bilirubin Level is Negatively Associated with the Incidence of End Stage Renal Disease in Patients with IgA Nephropathy

Oxidative stress plays various roles in the development and progression of IgA nephropathy, while bilirubin is known as a potent antioxidant. We therefore hypothesized that serum bilirubin would be associated with renal prognosis in IgA nephropathy. The study subjects comprised 1,458 adult patients with primary IgA nephropathy in Korea. We grouped patients according to the following quartile levels of bilirubin: <0.4 mg/dL (Q1), 0.4-0.5 mg/dL (Q2), 0.6-0.7 mg/dL (Q3), and >0.8 mg/dL (Q4). The outcome data were obtained from the Korean Registry of end-stage renal disease (ESRD). Eighty patients (5.5%) contracted ESRD during a mean follow-up period of 44.9 months. The ESRD incidences were 10.7% in Q1, 8.2% in Q2, 2.8% in Q3, and 2.8% in Q4 (p<0.001). The relative risk of ESRD compared to that in Q1 was 0.307 (95% confidence interval [CI], 0.126-0.751) in Q3 and 0.315 (95% CI, 0.130-0.765) in Q4. The differences of ESRD incidence were greater in subgroups of males and of patients aged 35 yr or more, with serum albumin 4.0 g/dL or more, with normotension, with eGFR 60 mL/min/1.73 m2 or more, and with proteinuria less then 3+ by dipstick test. In conclusion, higher bilirubin level was negatively associated with ESRD incidence in IgA nephropathy

Effects of annealing treatment prior to cold rolling on delayed fracture properties in ferrite-austenite duplex lightweight steels

Tensile properties of recently developed automotive high-strength steels containing about 10 wt pct of Mn and Al are superior to other conventional steels, but the active commercialization has been postponed because they are often subjected to cracking during formation or to the delayed fracture after formation. Here, the delayed fracture behavior of a ferrite-austenite duplex lightweight steel whose microstructure was modified by a batch annealing treatment at 1023 K (750 A degrees C) prior to cold rolling was examined by HCl immersion tests of cup specimens, and was compared with that of an unmodified steel. After the batch annealing, band structures were almost decomposed as strong textures of {100}aOE (c) 011 > alpha-fibers and {111}aOE (c) 112 > gamma-fibers were considerably dissolved, while ferrite grains were refined. The steel cup specimen having this modified microstructure was not cracked when immersed in an HCl solution for 18 days, whereas the specimen having unmodified microstructure underwent the delayed fracture within 1 day. This time delayed fracture was more critically affected by difference in deformation characteristics such as martensitic transformation and deformation inhomogeneity induced from concentration of residual stress or plastic strain, rather than the difference in initial microstructures. The present work gives a promise for automotive applications requiring excellent mechanical and delayed fracture properties as well as reduced specific weight.ope

How to Increase Sport Facility Users&rsquo; Intention to Use AI Fitness Services: Based on the Technology Adoption Model

Artificial intelligence (AI) has recently been introduced as a new way of analyzing and predicting sport consumer behavior. The goal of this study was to investigate the relationships among the perceived usefulness, perceived ease of use, the importance of exercise, attitudes towards use, and the behavioral intention to use AI services based on the technology adoption model. The authors recruited 408 participants who participated in an experiment designed to provide a deeper understanding of AI fitness services. After screening, the collected data were screened through assumption tests, and we conducted a confirmatory factor analysis and structural equation modeling to analyze research hypotheses. The results indicated that three types of consumer evaluations (i.e., perceived usefulness, perceived ease of use, and importance of exercise) positively influence their attitudes toward AI fitness services. In addition, the positive attitudes regarding AI services positively influenced the intention to use AI services. The results of this research contribute to our knowledge of the consumers&rsquo; attitudes and behaviors toward AI services in the sport industry based on the technology acceptance model. Furthermore, this study provided the empirical evidence critically needed to increase our understanding of AI in the sport industry and offered new insights into how sport facility managers can predict their consumers&rsquo; intention to use AI services

Correlation of Microstructure and Tensile and Cup Forming Properties of Aluminum-added TWinning Induced Plasticity (TWIP) Steels

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Suppressed deformation instability in the twinning-induced plasticity steel-cored three-layer steel sheet

Deformation instabilities (i.e., yield point phenomenon (YPP) and serrated flow) were investigated for twinning-induced plasticity (TWIP) steel-core with low-carbon (LC) steel outer layer sheets. During tensile tests, both the YPP and serrated flow were suppressed as the volume fraction of the TWIP steel-core decreased. Electron backscattering diffraction analysis indicated that a strain gradient was induced, and that geometrically necessary dislocations (GNDs) accumulated at the TWIP-LC steel interface. With increase in the dislocation density by plastic deformation, the deformation instabilities in the TWIP-cored layer steel sheets were suppressed due to the reduced probability of interaction of dislocation with carbon-solutes. This result indicates that the strain gradient at the interface of the layered sheets not only enhances the mechanical property, but also suppresses deformation instability. (C) 2018 Acta Materialia Inc. Published by Elsevier Ltd. All rights reserved.11Nsciescopu