Tensile property improvement of TWIP-cored three-layer steel sheets fabricated by hot-roll-bonding with low-carbon steel or interstitial-free steel

TWIP-cored three-layer steel sheets were newly fabricated by hot rolling of TWIP steel sheet surrounded by low-carbon (LC) or interstitial-free (IF) steel sheets. TWIP/LC or TWIP/IF interfaces were well bonded without pores or voids, while a few pearlites were thinly formed along the interfaces. The strengths and elongation of the TWIP-cored sheets increased as the volume fraction of TWIP-cored region increased, and were also well matched with the ones calculated by a rule of mixtures based on volume fraction or force fraction. According to digital image correlation and electron back-scatter diffraction analyses, very high strain hardening effect in the initial deformation stage and active twin formation in the interfacial region beneficially affected the overall homogeneous deformation in the TWIP-cored sheets without any yield point phenomenon occurring in the LC sheet and serrations occurring in the TWIP sheet, respectively. These TWIP-cored sheets can cover a wide range of yield strength, tensile strength, and ductility levels, e.g., 320-498 MPa, 545-878 MPa, and 48-54%, respectively, by controlling the volume fraction of TWIP-cored region, and thus present new applications to multi-functional automotive steel sheets requiring excellent properties.1163Ysciescopu

Photocatalytic H_2 production on trititanate nanotubes coupled with CdS and platinum nanoparticles under visible light: revisiting H_2 production and material durability

The photocatalytic production of molecular hydrogen (H_2) on ternary composites of Pt, CdS, and sodium trititanate nanotubes (Na_xH_(2−x)Ti_3O_7, TNTs) is examined in an aqueous 2-propanol (IPA) solution (typically 5 vol%) at a circum-neutral pH under visible light (λ > 420 nm). The H2 production rates are dependent on the Pt-loading level, and the optimum production rate in the Pt/CdS/TNTs is approximately six times higher than that in Pt/CdS/TiO_2. A D2O solution containing 5 vol% IPA leads only to the production of D_2 molecules, whereas increasing the IPA amount to 30 vol% leads to the production of DH molecules. This indicates that the Pt/CdS/TNTs composites enable H_2 production via true water splitting under our typical experimental conditions. X-ray photoelectron spectroscopy (XPS) analyses of the as-synthesized Pt/CdS/TNTs and those used for 6 and 12 h show that metallic Pt on the CdS/TNTs is less susceptible to oxidation than Pt on CdS/TiO_2. In addition, photocorrosion of CdS (i.e., sulfate formation) is significantly inhibited during the photocatalytic H_2 production reactions in the Pt/CdS/TNTs because of the efficient charge transfer via the TNTs framework. The Pt/CdS/TNTs samples are thermally more stable than Pt/CdS/TiO_2 and CdS/TNTs, effectively inhibiting the formation of CdO during the thermal synthesis. Detailed surface characterizations of the as-synthesized ternary composites are performed using X-ray diffraction, transmission electron microscopy, energy dispersive spectroscopy, and XPS

Bi-modal Structure of Copper via Room-Temperature Partial Recrystallization After Cryogenic Dynamic Compression

Pure copper was compressed at high strain rates (over similar to 3 x 10(3) s(-1)) under liquid nitrogen. This deformation resulted in bi-modal microstructures of ultrafine grains and abnormally grown micro grains, and in greater hardness (by similar to 30 Hv) than room-temperature, dynamically deformed copper. This bi-modal microstructure is attributable to partial recrystallization at room temperature, activated by high-energy states and by twins generated at high Zener-Hollomon parameter conditions. This result demonstrates a new approach for producing bi-modally structured materials.open1121sciescopu

Investigation of the mechanism of chromium removal in (3-aminopropyl)trimethoxysilane functionalized mesoporous silica

We are proposed that a possible mechanism for Cr(VI) removal by functionalized mesoporous silica. Mesoporous silica was functionalized with (3-aminopropyl)trimethoxysilane (APTMS) using the post-synthesis grafting method. The synthesized materials were characterized using transmission electron microscopy (TEM), X-ray diffraction (XRD), N-2 adsorption-desorption analysis, Fourier-transform infrared (FT-IR), thermogravimetric analyses (TGA), and X-ray photoelectron spectroscopy (XPS) to confirm the pore structure and functionalization of amine groups, and were subsequently used as adsorbents for the removal of Cr(VI) from aqueous solution. As the concentration of APTMS increases from 0.01 M to 0.25 M, the surface area of mesoporous silica decreases from 857.9 m(2)/g to 402.6 m(2)/g. In contrast, Cr(VI) uptake increases from 36.95 mg/g to 83.50 mg/g. This indicates that the enhanced Cr(VI) removal was primarily due to the activity of functional groups. It is thought that the optimum concentration of APTMS for functionalization is approximately 0.05 M. According to XPS data, NH3+ and protonated NH2 from APTMS adsorbed anionic Cr(VI) by electrostatic interaction and changed the solution pH. Equilibrium data are well fitted by Temkin and Sips isotherms. This research shows promising results for the application of amino functionalized mesoporous silica as an adsorbent to removal Cr(VI) from aqueous solution

Development of a new drug for progeria syndrome; Past, Present and Future

Hutchinson-Gilford progeria syndrome (HGPS) is the best characterized genetic disorder with premature aging features. Classic HGPS is very rare, sporadic orphan disease, inherited in an autosomal dominant manner without gender or ethnic differences. Children with HGPS appear normal at birth, but begin to develop segmental progeroid symptoms within the first years of life. Patients suffer from sarcopenia, lipodystrophy, diabetes, cataracts, atherosclerosis but not cancer and neurodegenerative diseases. Genetic factors that are associated with this syndrome have been identified, mouse models of disease have been developed, and clinical studies have been conducted for many years. Although many medical and treatment approaches were implemented and showed some efficacy, these therapies could not be considered as a complete cure, and more effective therapeutic approaches were needed for HGPS patients. This report introduces a novel drug called progerinin, which is a binding inhibitor of lamin A and progerin, for patients affected with HGPS.</p

Dynamic Compressive Deformation Behavior of Austenitic High-Manganese Steels Used for Extremely-Low-Temperature Applications

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Effects of Dynamic Strain Hardening Exponent on Abnormal Cleavage Fracture Occurring During Drop Weight Tear Test of API X70 and X80 Linepipe Steels

In this study, drop weight tear tests (DWTT) were conducted on API X70 and X80 linepipe steels fabricated with various compositions and rolling and cooling conditions in order to correlate the strain hardening with the abnormal cleavage fracture occurring in the hammer-impacted area. Area fractions of fracture modes were measured from fractured DWTT specimens, and the measured data were analyzed in relation to microstructures, Charpy impact energy, and strain hardening. All the steels consisted of fine acicular ferrite, together with some bainitic ferrite, granular bainite, and martensite-austenite constituent. As the volume fraction of acicular ferrite increased, the area fraction of DWTT abnormal cleavage fracture decreased because the toughness of acicular ferrite was higher than other microstructures. The area fraction of abnormal cleavage fracture was weakly related with strain hardening exponents obtained from the quasi-static tensile and compressive tests, but showed better correlation with those obtained from the dynamic compressive test. This tendency could be more clearly observed when steels having similar Charpy impact energy levels were grouped. Since the DWTT was performed under a dynamic loading condition, thus, the abnormal cleavage fracture behavior should be related with the strain hardening analyzed under a dynamic loading condition. (C) The Minerals, Metals & Materials Society and ASM International 2013open1123sciescopu

Alligatoring phenomenon occurring during hot rolling of free-machining steel wire rods

An investigation was conducted into effects of MnS inclusions on the alligatoring phenomenon which often occurred in hot-rolled free-machining steel wire rods fabricated by varying carbon content and cooling condition. In the wire rod containing high carbon content, MnS inclusions were continuously formed inside thin ferrite bands, and caused the cracking and the subsequent alligatoring. The wire rod containing low carbon content was often subjected to the alligatoring when a considerable amount of pearlite was formed by the slow cooling and thus ferrite bands were thinly formed between populated pearlite bands. On the other hand, the wire rods having thick ferrite bands were not cracked as MnS inclusions were homogeneously and discontinuously distributed inside thickened ferrite bands, even though a considerable amount of MnS inclusions were formed. These results were confirmed by the in situ observation of crack initiation and propagation occurring near a sharp notch tip and the R-curve behavior. In order to prevent the alligatoring, thus, it was recommended that the carbon content should be maintained below 0.1% at least, and that the fast cooling rate should be achieved above a certain cooling rate level to form MnS inclusions discontinuously inside thick ferrite bands. (c) 2013 Elsevier B.V. All rights reserved.X1133sciescopu

Inverse Fracture Occurring during Drop Weight Tear Teat (DWTT) and Stain Hardening Obtained from Dynamic Compressive Test in Lineplpe Steels

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