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This paper investigates the bond performance of reinforcing bars in thin concrete elements incorporating an innovative, patented 'ROBOVOID' void-former solution. A series of full-scale experiments, representing sub-assemblies of larger structures, were conducted using various bar sizes and configurations, bond length, concrete and reinforcing details. The results from the experiments were compared with results from the Australian Standard, European Code and American concrete design methods. The suitability of both standards was investigated and a design recommendation for ROBOVOID panels is presented. The bond length required to achieve full development of the reinforcing bar strength for ROBOVOID slabs can safely be ensured via the proper application of concrete design standards, and because of the thinner concrete panels and shallow internal concrete cover where the bars are placed directly on the plastic void forming components. [ABSTRACT FROM AUTHOR]

This study focuses on the oxidation behavior of oxide scale on hot-rolled steel from a Thailand steel industry. Hot-rolled steel established from the medium and thin slabs was studied. The oxidation behavior was conducted in a horizontal furnace with 20%H2O-N2 to simulate steel oxidation during the hot rolling line. The scale was formed at a temperature range of 600-900°C for 30, 60, and 90 min. The scale morphology can be seen via Scanning Electron Microscope (SEM-EDS). The oxide phase was investigated via X-Ray Diffraction (XRD). The results show that iron oxides such as hematite (Fe2O3) and magnetite (Fe3O4) were produced on the studied steel. The oxidation behavior of the studied steel was followed by a parabolic law. The mass gain increased with increasing temperatures. The steel established from a medium slab exhibited a lower oxidation rate than the steel established from a thin slab. The reason for this could be the high amount of oxide containing silicon at the steel-scale interface, which promoted the oxidation resistance of the steel established from the medium slab. The influence of different slab types and its alloying elements was studied to comprehend the oxidation behavior. As a result, the alloying element in the hot-rolled steel was controlled in the design process. [ABSTRACT FROM AUTHOR]

Purpose: Susceptibility maps reconstructed from thin slabs may suffer underestimation due to background‐field removal imperfections near slab boundaries and the increased difficulty of solving a 3D‐inversion problem with reduced support, particularly in the direction of the main magnetic field. Reliable QSM reconstruction from thin slabs would enable focal acquisitions in a much‐reduced scan time. Methods: This work proposes using additional rapid low‐resolution data of extended spatial coverage to improve background‐field estimation and regularize the inversion‐to‐susceptibility process for high resolution, thin slab data. The new method was tested using simulated and in‐vivo brain data of high resolution (0.33 × 0.33 × 0.33 mm3 and 0.54 × 0.54 × 0.65 mm3, respectively) at 3T, and compared to the standard large volume approach. Results: Using the proposed method, in‐vivo high‐resolution QSM at 3T was obtained from slabs of width as small as 10.4 mm, aided by a lower‐resolution dataset of 24 times coarser voxels. Simulations showed that the proposed method produced more consistent measurements from slabs of at least eight slices. Reducing the mean ROI error to 5% required the low‐resolution data to cover ˜60 mm in the direction of the main field, have at least 2‐mm isotropic resolution that is not coarser than the high‐resolution data by more than four‐fold in any direction. Conclusion: Applying the proposed method enabled focal QSM acquisitions at sub‐millimeter resolution within reasonable acquisition time. [ABSTRACT FROM AUTHOR]

A rolling force model is established by using the unified yield criterion, in which both the changes of the slab temperature and the radius of the roller are considered. In order to solve the integral problem of the nonlinear specific plastic work rate, the unified yield criterion is used to analyse a simplified velocity field, and the internal deformation power is derived. Then, the shear power and friction power are also calculated based on the velocity field, and the total power is obtained by summarising these derived formulas. Finally, the analytic solution of rolling force in terms of the unified yield criterion is obtained by the variational method. Thereafter, the measured data from one domestic factory is used to check the analytical solution of rolling force, in which the temperature drop from the slab inlet to its outlet is considered. Meanwhile, the roller flattening is also considered. It is shown from the comparison and discussion that: the Mises yield criterion that is a special case of the unified yield criterion is more accurate in predicting the rolling force; the thinner the slab is, the more the temperature drop is; the calculation results by considering the roll flattening are improved. [ABSTRACT FROM AUTHOR]

Special features of deformed condition of commercial thin slabs produced in a continuous cycle in a casting and rolling unit are studied. Quantitative metallography is used to measure the parameters of the dendrite structure at different degrees of reduction during the deformation of slabs in the roughing group. The changes occurring in the primary dendritic structure during the deformation are considered. It is shown that the relative change in the sizes of the dendrite structure over the thickness of the slab corresponds to the degree of the relative reduction under the rolling. The picture of strain distribution over the thickness of the pieces is presented. [ABSTRACT FROM AUTHOR]

Using the finite element method and the heat conduction equation, the temperature, stress, and end-face deformation in Tm:YAP crystal under high pump power were analyzed. Combined with gradient doping technology, an effective way to improve the internal heat distribution of the crystal was studied. The results showed that when the total pump power was 200 W, under the same cooling conditions, the maximum temperature difference inside Tm:YAP decreased from 58 K to 25 K after gradient doping. The thermal stress and end-face thermal deformation were also significantly improved. In addition, a reasonable micro-channel structure also effectively removed the heat generated inside the crystal. [ABSTRACT FROM AUTHOR]

When the thin slab caster produces low-carbon steel, the uneven cooling alarm can easily occur at both sides of the nozzle in the thermal image, and there are cracks at the corresponding positions where the uneven cooling occurs. The causes of uneven cooling are studied, and the mechanism of uneven cooling causing surface cracks is proposed. The results show that the generation of uneven cooling is greatly related to the carbon content of molten steel, the thickness of the copper plate, and the hydrogen content. The surface roughness method shows that the uneven cooling index increases with the increase of carbon content. The uneven cooling index gradually increases with the decrease of the copper plate thickness. When the copper plate thickness is less than 41 mm, the uneven cooling index of the mold increases from the 1.1 to about 14.7. With the increase of H content, the uneven cooling index increases. When H exceeds 7 ppm, the uneven cooling index can reach 14.5. By adopting reasonable and effective control measures, the uneven cooling index of the mold is significantly reduced from 3.85 to 0.73, and the surface crack defects in multi-mode continuous casting-rolling line are effectively alleviated. [ABSTRACT FROM AUTHOR]

Continuous casting (CC) is nowadays the world‐leading technology for steel production. The thin slab casting (TSC) is featured by a slab shape close to the final products and a high casting speed. The quality of the thin slabs strongly depends on the uniformity of the turbulent flow and the superheat distribution, defining the solid shell growth against a funnel‐shaped mold. In most studies, it is commonly assumed that the submerged entry nozzle (SEN) is properly arranged, and the melt inflow is symmetric. However, the misalignment or clogging of the nozzle can lead to an asymmetric flow pattern. Herein, the asymmetry is imposed via a partial SEN clogging: a) a local porous zone inside the nozzle reflects the presence of the clog material; b) the resistance of the clog is varied from low to high values. The solidification during TSC is modeled, including the effects of the turbulent flow. The variation of the flow pattern and the solidified shell thickness are studied for different permeability values of the SEN clogging. These effects are considered with and without the applied electromagnetic brake (EMBr) using an in‐house magnetohydrodynamics (MHD) and solidification solver developed within the open‐source package OpenFOAM. [ABSTRACT FROM AUTHOR]

Effective control of intense turbulence is a crucial challenge for achieving steady production with ultra-high casting speed in thin slab continuous casting. In thin slab casting process, specially designed multi-port submerged entry nozzle (SEN) with four outlets is utilised to ensure an ample supply of molten steel, necessitating the selection and optimisation of suitable Electromagnetic Braking (EMBr) equipment for steel jet control. This study established a comprehensive three-dimensional model of a funnel-type mould, employing a combined experimental-numerical approach to validate and investigate the flow, heat transfer, solidification and electromagnetic behaviour in the mould. The steel grade studied in the simulation is Q235B, and its physical properties were calculated based on its composition with a temperature range of 1450–1826 K. To analyse the influence of high casting speed on the flow and solidification behaviour in the mould, three casting speeds were selected for the study, which were 6, 7 and 8 m/min. The results indicate that the novel Bowl EMBr significantly suppressed the penetration of steel jet and thus enhanced the thickness and uniformity of the solidified shell. As the casting speed increases from 6 to 8 m/min, the solidified shell thickness at the mould exit decreases from 7.91 to 5.94 mm, with the stagnant growth region approaching the mould exit. This highlights the requirement to correspondingly increase EMBr strength under ultra-high casting speed condition to avoid remelting of the shell and the risk of molten steel leakage. The coupled mathematical model established in this study provides guidance for optimising EMBr structures and casting speed under special multi-port SEN conditions, offering recommendations for the rational control of flow, heat transfer and solidification process in the mould. [ABSTRACT FROM AUTHOR]

Improvement of macrostructure indicators of slabs during continuous casting of steel on a thin-slab machine of the sheet-rolling shop of Vyksa Steel Works JSC was achieved by introducing the latest programs into the automation system for the soft reduction process. [ABSTRACT FROM AUTHOR]

Using the finite element method and the heat conduction equation, the temperature, stress, and end-face deformation in Tm:YAP crystal under high pump power were analyzed. Combined with gradient doping technology, an effective way to improve the internal heat distribution of the crystal was studied. The results showed that when the total pump power was 200 W, under the same cooling conditions, the maximum temperature difference inside Tm:YAP decreased from 58 K to 25 K after gradient doping. The thermal stress and end-face thermal deformation were also significantly improved. In addition, a reasonable micro-channel structure also effectively removed the heat generated inside the crystal.

[Display omitted] • The TSCR process is key for producing thinner NO electrical steel sheets. • Cold-rolling reduction ratio crucially influences NO steel magnetism. • Hot-rolled sheet thickness minimally impacts microstructure and texture. • Thinner TSCR sheets improve NO steel's magnetic characteristics. Non-oriented (NO) electrical steel sheets with a thin thickness are drawing interest as potential materials for electric vehicle drive motor cores due to their ability to reduce high-frequency core loss. To produce electrical steel sheets with a thickness of 0.25 mm or less, it is beneficial to minimize the thickness of the hot-rolled sheets. However, it is well known that it is difficult to achieve hot-rolled coils with a thickness of 1.4 mm or less with a conventional hot rolling process. Therefore, the thin slab casting and rolling (TSCR) process is now used to produce thin hot-rolled coils that cannot be produced by conventional methods. In this study, we investigated the effects of hot-rolled sheet thickness produced by the TSCR process and cold-rolling reduction ratio on the crystallographic texture, microstructure, and magnetic characteristics of 3% Si NO steel. The results showed that the textures of the hot-rolled sheet and the annealed hot-rolled sheet are virtually unaffected by the hot-rolling reduction ratio. However, the cold-rolling reduction ratio substantially affects many aspects of NO electrical steels. The recrystallized grain size after the final annealing process decreases as the cold reduction ratio increases, while the magnetic flux density decreases with increasing cold reduction ratio, especially for reductions exceeding 82.8 %. In conclusion, the thickness of hot-rolled steel sheets manufactured by the TSCR process has little effect on the microstructure and texture of hot-rolled sheet. Therefore, reducing the cold rolling reduction ratio, which can be achieved by using thin hot-rolled sheets manufactured by the TSCR process, is a promising method for enhancing the magnetic characteristics of thin-gauge NO electrical steel sheets. [ABSTRACT FROM AUTHOR]

• Over 200 pull-out tension tests for headed studs with varying embedment depths were tested in early age thin concrete panels from 2 to 7 days old. • A modification to the Concrete-Capacity (CC) method was proposed based on reliability studies for new application investigated in this study. • A recommendation is provided for provision of stud connectors to safely resist bursting pressures during concrete filling operation. In recent times, voided concrete slab or wall system has been increasingly popular due to material and cost savings benefits offered by such system. Fastenings are required to be attached to such systems either to connect to other concrete elements or fixtures. There has been limited published literature on the performance of fastenings in thin concrete shell elements due to presence of voids. The Concrete Capacity (CC) method is the state-of the-art prediction model for capacity of anchors in concrete widely adopted in design standards worldwide. The CC-method has been proven to be a robust model for predicting concrete cone capacity of cast-in and post-installed anchors with effective embedment depths, h ef between 4 and 20 times diameter of anchors with a minimum h ef of 40 mm in mature age concrete. In this study, over 200 headed studs are investigated experimentally in early age concrete whereby the h ef for over half of the specimens is lesser than 40 mm. Further, the failure mode for the headed studs in the presence of plastic void former is expected to be a plug failure which prohibits the development of the full concrete cone. The purpose of this study is to examine the applicability of the CC-method for pull out performance of headed studs in the presence of void formers. A total of 228 headed anchors with varying effective embedment depths ranging from 19 mm to 61 mm were tested in thin concrete panels with varying thicknesses. Based on structural reliability analysis, a modification factor was proposed to the CC-method to safely predict the pull-out design capacity of headed studs in thin concrete panels with plastic void formers to maintain the same degree of safety as for typical headed stud applications within the scope of the CC-method. [ABSTRACT FROM AUTHOR]

Thermal effect is a key problem to obtain high average power output from the Fe:ZnSe crystal. Main parameters of micro-channel structure heat sink, such as channel depth, width and duty cycle are designed and optimized to improve the dissipation capability. And on these basis, a thin-slab and composite Fe:ZnSe model is constructed and the temperature distribution of the Fe:ZnSe is analyzed and discussed. [ABSTRACT FROM AUTHOR]

It is very necessary to predict the residual velocity of a projectile after perforating a concrete barrier for the protective structures. In this paper, projectile perforation test on the thin 128.4 MPa ultra-high performance steel fiber reinforced concrete (UHP-SFRC) slabs was conducted, in which the diameter of projectile was 25.3 mm and the thicknesses of slabs ranged from 40 mm to 100 mm. All the slabs were perforated normally and the projectile residual velocities were captured by high-speed camera. To assess the projectile residual velocity, a semi-analytical projectile perforation model for thin concrete slab ( H / d  ≤ 5) was established, which completes our previous work [Peng et al., 2015] for thick slab ( H / d  > 5) within a unified framework. The proposed model was validated by the present and existing available perforation test data on thin concrete slab. Furthermore, the unified model was employed to evaluate the impact resistance of spaced segmented concrete slabs and good agreements were achieved. [ABSTRACT FROM AUTHOR]

Results are presented from mathematical modeling of the deformation of a thin slab in a continuous-caster mold with a conical cavity. The objective is to deform the slab in such a way that the free gap between the slab and the narrow wall of the mold changes linearly with a change in casting speed. It is established that the convexity formed in the central part of the slab's broad face may still be present on the slab when it leaves the mold. A process which involves compression of the slab is examined as a means of eliminating the residual convexity. [ABSTRACT FROM AUTHOR]

Studies are made of geometric relations which show how the amplitude, width, and length of the conical part of continuous-caster molds can be changed so as to ensure that the gap between the mold's narrow wall and the skin of the slab being cast is linear. [ABSTRACT FROM AUTHOR]

A mathematical model is formulated for deformation of a thin slab shell in a mold with a nonlinear internal profile taking account of metal volumetric stressed state and friction between a slab shell and mold surface. Values of axial stresses within a shell and the amount of change in slab broad face size are analyzed. [ABSTRACT FROM AUTHOR]