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In order to improve the quality of the transition slabs, the large‐size inclusions in 28 m‐long transition slabs are studied by large sample electrolysis and thermodynamic analysis. The results reveal that the length of transition slabs influenced by ladle exchange is 17 m, which is 4 m before the second steel ladle casting and 13 m after the casting. Large‐size inclusions in transition slabs can be divided into five kinds of Al2O3, Al2O3‐CaO, Al2O3‐CaO‐SiO2, Al2O3‐CaO‐MgO, and entrapment slag. The average contents of total inclusions, the inclusions in the range of 30–100 μm, those of 100–200 μm, and those larger than 200 μm in the transition slabs are 4.8, 19, 2.8, and 4.2 times higher than those in the normal slabs, respectively. For the large inclusions greater than 200 μm, the average contents of the Al2O3, Al2O3‐CaO‐SiO2 inclusions, and entrapment slags significantly increase in the transition slabs, being 9.4, 13.1, and 2.4 times higher than those in the normal slabs, respectively. The sources of Al2O3, Al2O3‐CaO‐SiO2 inclusions, and entrapment slags should be the secondary oxidation in tundish, entrapment of tundish flux, and entrapment of mold powders, respectively. [ABSTRACT FROM AUTHOR]

The Kirigami technique has recently inspired the design of reconfigurable electromagnetic metamaterials that can be easily realized by embedding a patterned cutting array into a supportive substrate. However, these existing designs mainly focus on the 2D‐to‐3D transformable morphology that induces the modulation of the spectral responses. This work proposes a kirigami‐based planar reconfiguration mechanism and extends advanced applications in the dynamic near‐field imaging and tunable double‐foci metalens. These extraordinary tunabilities originate from three meta‐atoms that can be mutually transformed into the morphologies with non‐chirality and opposite chirality under the tensile strain. By utilizing the transmittance characteristics of reconfigurable meta‐atoms, the metamaterial is constructed to achieve three‐foldable near‐field displays and a longitudinal double‐foci metalens empowered with tunable focusing length and intensity ratio. Two anisotropic chiral meta‐atoms in deformed states that possess overwhelming transmittance difference of circularly cross‐polarized components to magnify the focusing intensity ratio of two foci for the proposed metalens are further proposed. The exhibited observations provide typical examples of a wide spectrum of applications of the kirigami‐based reconfiguration mechanism, and it may pave the avenue to spark manifold functional devices for applicable electromagnetic manipulations such as multifunctional hologram display, dynamic beam shaping, and steering, as well as the conformal design of meta‐devices. [ABSTRACT FROM AUTHOR]

In view of the service failure and low continuous casting production efficiency due to the corrosion of refractories at the slag-line in submerged entry nozzles, a submerged entry nozzle for low-carbon aluminum killed steel continuous casting in one steel plant was sampled and taken as the research object to analyze the causes and the mechanism of refractory corrosion at the slag-line. The results show that the core issue of the corrosion and necking of the slag-line materials is that the slagline material are eroded, dissolved, and reacted by the mold flux gradually. Therefore, it is important to suppress or avoid the contact and reaction between the mold flux and slag-line materials. [ABSTRACT FROM AUTHOR]

In the present work, inclusion analyses were carried out for inclusions in the tundish samples and in the 28 m transition slabs produced during the ladle exchange of heats A and B. At the beginning of heat B steel casting, the 12th meter of the casting slabs was in the position of the mold meniscus. The number of densities of the inclusions containing TiN and the inclusions containing Al2O3+TiN increased significantly from the 12th meter to the 22nd meter, while the number densities of the inclusions containing Al2O3 markedly increased from the 13th meter to the 20th meter. Therefore, the length of the transition slabs whose cleanliness was seriously reduced was about 10 m starting from the beginning of heat B steel casting. It was deduced that the contamination of the transition slabs could be caused by the liquid steel exposure in the tundish, the inflow of ladle filling sand of the next heat, or the entrainment of the tundish flux due to the fluctuation of the tundish liquid level at the beginning of heat B steel casting. [ABSTRACT FROM AUTHOR]

To prevent volcanic ash corrosion using thermal barrier coatings (TBCs), a novel method using Al2O3-modification was proposed to reduce molten CMAS wettability on TBCs surface through a lotus effect. Plasma spray-physical vapor deposition (PS-PVD), a third-generation method for TBCs fabrication, was adopted to deposit 7YSZ TBCs with a feather-like microstructure. Then, Al2O3 modification was introduced to fabricate a dense Al2O3 overlay with nano/micro-sized grains on the TBCs surface. The wetting ability of CMAS on APS/EB-PVD/PS-PVD 7YSZ TBCs was comparatively in situ observed at 1250 °C for 3600 s. The results indicated that the dense Al2O3 overlay inhibited penetration of molten CMAS. Additionally, the micro/nano dual-sized structure, which is similar to the papillary structure of a lotus leaf, reduced molten CMAS wettability on the TBCs surface. The results demonstrated that the Al2O3-modified TBCs had better CMAS corrosion resistance than the as-deposited APS/EB-PVD/PS-PVD TBCs. [ABSTRACT FROM AUTHOR]

The relationship between the microstructure and impact toughness of coarse‐grained heat affected zone for offshore engineering steels with 0.0002 and 0.0042 wt% Mg, termed as 2 and 42Mg, respectively, is clarified. With increasing the Mg content from 0.0002 to 0.0042 wt%, the average impact energy at −40 °C decreases from 201 to 59 J. The prior austenite grain size (PAGS) increases from ≈92 to ≈163 μm, the average thickness of lath bainites increases from ≈234 to ≈361 nm. The addition of Mg makes the particle increase in number and refine in size, but the amount of the effective pinning particles at the temperature close to 1350 °C in 42Mg is smaller than that in 2Mg, which leads to the larger austenite grain growth rate and larger PAGS in 42Mg. The larger PAGS with the higher bainite transformation temperature and smaller PAG boundary density in 42Mg makes the bainite coarser. So, in 2Mg, the effective bainitic grain size with misorientation above 45° is smaller and the density of high‐angle grain boundaries (HAGBs) is larger, resulting in its higher toughness. Besides, the coalesced bainite containing cementite colonies in 42Mg makes the bimodal bainitic lath thicknesses and heterogeneous microhardness distribution, reducing the toughness. [ABSTRACT FROM AUTHOR]

A single-wire cutting experiment on the polycrystalline diamond by UV nanosecond laser was carried out. The result was characterized and analyzed by the scanning electron microscope and XPS energy spectrum analysis. It found that the width and depth of grooves continue to increase with the increasing of laser power, scanning times, and the decreasing of scanning speed. A finer groove with a narrower width and deeper depth can be obtained by adjusting the focus point on the surface of the PCD material. XPS spectrum of C1s indicated that sp3 structure converts to the sp2 graphite phase and removed by photochemical mechanism when the UV nanosecond laser irradiates the PCD. Moreover, the cutting result suggests that UV nanosecond laser can achieve finer processing of PCD material. [ABSTRACT FROM AUTHOR]

Laser polishing, as a novel surface processing technology, has been successfully employed for improving the surface smoothness and geometric accuracy of components for metals, glasses, fibers and ceramics. However, continuous wave and microsecond and nanosecond lasers leads to some undesirable defects of the polished surface, such as heat affected zone, debris redeposition and thermal stress induced microcracks, especially for hard brittle materials. To solve this issue, this article investigated femtosecond laser polishing of SiC ceramics. Influence of pulse energy and scanning speed on surface roughness and surface morphologies was studied. In addition, the relationship between laser parameters and surface roughness and removal depth of SiC ceramics has been revealed. The experimental results indicated that the polished surface without big voids and spalling was obtained through optimizing femtosecond laser parameters. [ABSTRACT FROM AUTHOR]

High-power millisecond laser is an efficient tool to manufacture micro holes, but the laser induced thermal defects, such as recast layer (RL), micro cracks and heat affected zone, are difficult to avoid. However, some important components, like turbine blades, are very sensitive to these defects, therefore, they must be eliminated in the manufacturing process of film cooling holes. We propose a combined processing method which includes high-power laser pre-drilling and electrochemical post-processing. One novelty of this study is that we applied a special back-bonded material (silicate mixture) under the Inconel 718 substrate, which functions as barricade to protect the opposite inner surface of the hollow blade in laser drilling, while in the electrochemical process, it functions as bottom support to form electrolyte back flow. A novel two-step inner streaming electrochemical post-processing technique was designed according to the characteristics of RL distribution in the laser pre-drilled holes. The processing strategy was optimized by a series of experiments. Finally, recast-layer free holes with clear and straight hole walls could be drilled in less than 30 s each, which is much faster than ultrafast laser drilling. [ABSTRACT FROM AUTHOR]