Hot Steel Plate Research Articles

Jet impingement quenching of a hot steel plate using a surfactant added CuO nanofluid

The mechanical properties of the steel are significantly impacted by the cooling rate. In the steel industry, cooling rates on the run-out table customizes the microstructure of the steel plate, which enhances plate strength. In this research, the AISI 304 steel plate underwent cooling from a starting surface temperature of 900 °C. The effect on the jet cooling of a steel plate has been investigated using surfactant-added CuO nanofluid and methanol-added CuO nanofluid. It was found that using surfactant-added CuO nanofluid and methanol-added CuO nanofluid as a coolant, the cooling rate increased by 32.09 % and 38.66 %, respectively, in contrast to pure water.

Synthesis, characterization and application of SiO2 and CuO nanofluid in spray cooling of hot steel plate

Synthesis, characterization and application of SiO2 and CuO nanofluid in spray cooling of hot steel plate

Quantitative thermal investigation of a fayalite particle and a Si-rich layer in oxide scale formed on steel

Fayalite (Fe2SiO4) is a major component of olivine and is often formed in the surface oxide layer (oxide scale) on steel plates owing to its high-temperature oxidation. The thermal conductivity of the oxide scale and its constituents, including fayalite, is essential for controlling the cooling rate of hot steel plates. Therefore, this study uses modulated thermoreflectance microscopy to determine the thermal effusivity/conductivity of fayalite particles with diameters smaller than 180 μm because the sample commercially available is such a small size. This thermal optical microscopy enables the measurement of thermal effusivity for small areas, such as 10 μm. The thermal effusivity and conductivity were found to be 4.1 ± 0.2 kJs-0.5K-1m-2 and 6.0 ± 0.5 Wm-1K-1, respectively. These values are representative of the bulk value. Additionally, the thermal conductivity of fayalite is shown to be higher than that of wüstite (Fe1-xO), which is the main component of the oxide scale. The oxide scale formed on the thick steel plate comprises a Si-rich layer, a wüstite layer, and a magnetite layer. Furthermore, the Si-rich layer comprises fayalite, wüstite, and pores. The effective thermal conductivity of the Si-rich layer was calculated by observing the oxide scale formed on the steel plate. The low thermal conductivity of the Si-rich layer indicates that the thermal conductivity of the layer is strongly affected by the porosity of the oxide scale. Furthermore, although the Si-rich layer is thin, it significantly contributes to the heat resistance of the oxide scale.

Determination of Impingement Cooling Fluid Temperature-Time Profile For Extracted Tiger-Nut Juice (Cyperus Esculentus) By Lumped Thermal Mass Analysis

Determination of Temperature-Time Profile by the Lumped thermal mass analysis (LTMA) method using Tiger-Nut Juice as the impinging fluid on the cooling system was carried out. With a stationary hot steel plate on a modified run-out table for the top surface controlled the accelerated cooling process. This was evaluated with pipe diameters of 10mm, 15mm, 30mm, 35mm, and 40mm by single jet Tiger-Nut Juice impinging fluid, impingement gaps of 115mm, 125mm, 135mm, 145mm, and 155mm, initial surface temperatures from 450oC – 410oC and at sub-cooled temperatures from 150oC–110oC. The analysis reveals a faster cooling rate for both diameters at an impingement gap of 155mm. Diameter 10mm with 1.8oC/sec average rate, for impingement gap of 115mm, 1.8oC/sec for impingement gaps of 125mm, 135mm and 145mm and 1.9oC for 155mm. This optimal temperature-time profile of Tiger Nut Juice impingement cooling infers that a higher cooling rate is achieved using smaller pipe diameter D and higher impingement gap H. In addition, it showed evidence of less Leiden frost phenomenon; hence, extracted tiger nut juice fluid can perfectly serve as a substitute for water at smaller pipe diameters and higher impingement gaps. Also, it was inferred that it also cools at a bigger pipe diameter with a lower impingement gap.

Investigations on the lateral-torsional buckling of an innovative U-shaped steel beam

An innovative solution of a steel-concrete composite beam was developed for buildings with beam spans between 6 and 12 m, taking into consideration the fire situation and the construction stage. The beam is composed of an U-shaped steel part, connected to a reinforced concrete part. In the construction phase, the beam is supporting the slab and constitutes a formwork for the reinforced concrete part. When casting concrete, the steel beam is filled at the same time as the slab, this allows considerable time savings on site. In the exploitation stage, the beam behaves as a steel-concrete composite beam.The developed U-shaped section is composed of three steel parts; a hot rolled steel plate (180x8x6300 mm, and two cold-formed steel plates (470x4x6300 mm) before folding. The section was assembled together with four self-drilling screws longitudinally spaced of 150 mm.In the construction stage, the U-shaped steel beam without restraints is prone to lateral torsional buckling instability. In this paper, the mechanical behaviour of the steel beam at the construction stage, in particular its lateral-torsional buckling stability, was studied. In order to characterize this instability without lateral support, a four-point bending test was carried out on a life-size specimen. The load introduction system was developed especially for the test to allow for all displacements due to LTB. The test clearly showed the lateral torsional buckling behaviour of the steel beam. The test results are compared with numerical simulations and analytical studies. A parametrical study, covering 200 geometrical configurations of the U-shaped beam, is carried out to validate the use of the curve “b” for the design of the steel beam for lateral torsional buckling according to Eurocodes 3.

Microstructure and properties of Nb, V and N alloyed low magnetic hot rolled stainless steel plate

Microstructure and properties of Nb, V and N alloyed low magnetic hot rolled stainless steel plate

Non-Uniform Deformation of Slab during Heavy Reduction Process

The bulge deformation of slab narrow face can cause surface defects of hot rolled steel plate. A three-dimensional bulging model, was proposed to simulate the evolution of deformation behavior of the continuous casting slab during heavy reduction (HR). The model was taken to investigate the non-uniform deformation of slab during HR process. The bulging deformation behavior of the slab was then calculated in one segment included seven pairs of rollers. To improve the edge defect on hot-rolled steel plates, the relationship between the reduction amount and bulge deformation of slab narrow face has been investigated.

Sequential Inverse Heat Conduction Problem in OpenFOAM

The solution of the inverse heat conduction problem (IHCP) is commonly found with the sequential algorithm known as the function specification method with explicit updating formulas and sensitivity coefficients of heat flux. This paper presents a different approach namely a direct mathematical optimization of minimizing the least squares norm between experimental data and simulation. A CFD open-source code OpenFOAM is used together with NLOPT and DLIB optimization libraries. To guarantee credibility of the simulation tool developed herein, real experimental data is used from spray cooling of a fast-moving hot steel plate. As the IHCP is inherently an ill-posed problem, the proposed sequential algorithm is stabilized using future time stepping and thereof the optimal number is explained. An assumption about the profile of thermal boundary condition during future steps must be made. It is shown that assuming a linear change of the heat transfer coefficient during each sequence of future time steps yields more accurate results than setting a constant value. For the problem size considered with less than 10k cells, the preconditioned conjugate gradient (FDIC) linear solver converges faster than the multigrid solver (GAMG). However, the latter performs better as the accuracy is concerned. Concerning the best choice of minimizer, the BOBYQA algorithm (quadratic approximation) is found superior to other methods. The proposed IHCP solver is compared with the well-established one.

Experimental investigation of heat transfer characteristics during water jet impingement cooling of a high-temperature steel surface

ABSTRACT The microstructure and mechanical properties of the hot rolled steel depend on the laminar jet cooling control on the runout table. An experimental and numerical study of the heat transfer during water jet impingement cooling of a hot steel plate (600 to 900°C) is presented. The effects of plate temperature upon the heat transfer were analyzed by the inverse heat conduction method that provided the heat fluxes on top surface from measured temperatures into the plate. Rewetting (liquid-solid contact) occurs on surface above 880°C. Higher initial temperatures enlarge the heat flux, but delay the onset of the rewetting and the advance of rewetting front radius (Rwet). Heat transfer coefficient (HTC) increases as surface temperature decreases. The size of the non-symmetric effective jet cooling zone depends on strip speed. Correlations to predict HTC and Rwet have been proposed. Results will contribute for enhancement of fast cooling system in hot strip mill.

Film boiling in quench cooling with high-temperature jets

In the steel industry, quench cooling is used in the Run Out Table (ROT) to define the steel microstructure and mechanical properties. Film boiling is the preferred boiling regime in the ROT since its characteristic homogeneous and constant heat flux leads to a stable and controllable operation. The collapse of the vapor layer formed during film boiling, or rewetting, leads to a sharp increase in heat flux resulting in process complications such as uneven cooling, poor product quality, and deformation of the steel strips. In this study, the use of high-temperature water jets during the quenching of hot steel plates resulted in the formation of a stable vapor layer and long periods of film boiling. High-speed recordings are used to observe the dynamics of the vapor layer collapse. Surface heat flux estimations during quenching indicate an increase of vapor layer thickness with increasing distance to the jet location. The vapor layer collapse occurs at a surface temperature comparable to the Thermodynamic Limit of Superheat of water (302°C). The effects of surface roughness, initial surface temperature, and water jet temperature in the stability of the film boiling regime are studied. Surface roughness is found to increase the rewetting temperature and the surface heat fluxes after the collapse of the vapor layer. Increasing water jet temperature leads to decreasing rewetting temperatures and surface heat fluxes and therefore has the potential to widen the ROT stable operation window.

Online prediction of mechanical properties of hot rolled steel plate using machine learning

In industrial steel plate production, process parameters and steel grade composition significantly influence the microstructure and mechanical properties of the steel produced. But determining the exact relationship between process parameters and mechanical properties is a challenging process. This work aimed to devise a deep learning model, to predict mechanical properties of industrial steel plate including yield strength (YS), ultimate tensile strength (UTS), elongation (EL), and impact energy (Akv); based on the process parameters as well as composition of raw steel, and apply it online to a real steel manufacturing plant. An optimal deep neural network (DNN) model was formulated with 27 inputs parameters, 2 hidden layers each having 200 nodes and 4 output parameters (27 × 200 × 200 × 4) with an initial learning rate 0.0001, using Adam optimizer and subjected to Z pre-processing method, to yield an accurate model with R2 = 0.907. The tuned DNN model, had a root mean square error of 21.06 MPa, 16.67 MPa, 2.36%, and 39.33 J, and root mean square percentage error of 4.7%, 2.9%, 7.7%, and 16.2%, for YS, UTS, EL and Akv respectively. Through comparative analysis, it was found that the accuracy of DNN model was higher than other classic machine learning algorithms. To interpret the model assumptions and findings, several local linear models were devised and analyzed to establish the link between process parameters and mechanical properties. Finally the tuned DNN model was deployed in the real-steel plant for online monitoring and control of steel mechanical properties, and to guide the production of targeted steel plates with tailored mechanical properties.

Mitigation of uncommon peel-off defects in galvanized steel sheets

Galvanizing defects occurring in hot-and cold-rolling procedures were studied by scanning electron microscopy and focused ion beam, and analyzed via the JMP software. The results show that, among the 200 bright spots dispersed along the hot dipping steel plate, the defect may be misidentified as zinc slag by the representation of coating surface, but there exists a tiny peel off on the matrix without oxide particles under each spot. Upon partial removal of zinc coating, a tiny iron film outcropped from the coating was revealed. As some of iron films are not adhered to the matrix, such outcrops are not detected. The cross-sectional morphology shows the formation of inhibition layer, with no oxide between the peel off and matrix. The relative cold and hot rolling plates are also analyzed to trace the source, that the defect is inherited from hot rolling process according to the results. By using JMP to calculate the relationship of hot rolling parameters with the defect, slab heating temperature is concluded as a strong correlation condition. The high slab heating temperature ensures smooth rolling procedure, but the intergranular binding force is too low, which enhances the coating surface separation from the matrix. After reducing the slab heating temperature from 1350 to 1300°C or lower, and optimization of descale and pickling parameters, the occurrence ratio of bright spot defects caused by peel-off was significantly reduced.

Performance Evaluation of Solar Collector Having Broken Arc Ribs Of Symmetrical Gap with Staggered Elements

To experimentally investigate the thermal behaviour of solar collector with broken arc artificial roughness of symmetrical gap and staggered element, a study is conducted with four number of absorber surface of hot rolled steel plate of dimensions 1500 mm x210 mm x1.2 mm (length x width x thickness). The test dimension of plate was 1500 mm x 200 mm (LxW). The test parameters were relative roughness pitch P/e as 8-14, relative roughness height e/Dh as 0.04545, number of gaps Ng as 2, relative gap width g/e as 1, relative staggered length r/e as 4.5, relative staggered pitch p’/p as 0.4 and Reynolds number 3000-15000. The highest Nusselt number recorded at staggered length 3.5 was 5 times smooth plate. The highest thermohydraulic performance was recorded 1.85 for the same value of relative staggered length.

Application of binary mixed surfactant additives in jet impingement cooling of a hot steel plate

The current research aims at investigating role of three different types of surfactants and their binary mixtures in producing high cooling rate during jet impingement on a hot steel plate (100 mm × 100 mm × 6 mm) having initial surface temperature above 900 °C. The surfactants used are Sodium dodecyl sulphate (anionic), cetyltrimethylammonium bromide (cationic) and Polysorbate 20 (Tween 20, non-ionic). The surface tension values of the surfactants and their mixed systems have been measured and it has been observed that the binary mixtures at specific compositions show lower surface tension compared to the pure ones mainly due to synergism. The cooling results reveal that the mixture of cationic and non-ionic surfactants produces the highest cooling rate amongst all the systems. The maximum cooling rate achieved is 182 °C/s for the composition of 25 vol% CTAB and 75 vol% Tween 20 and it is 67% more than that of pure water, 23% more compared to pure CTAB and and 7.7% more than that of pure Tween 20. Thus it can be seen that ultrafast cooling of a 6 mm thick steel plate can be achieved by using optimized concentrations of mixed surfactant additives and this leads to improvement of quality of steel produced.

The role of dissolved carbon dioxide in case of high mass flux spray quenching, dropwise and flow boiling on a hot steel plate

In the current work, by altering the vapour bubble formation and their coalescence rate, the Leidenfrost effect is tried to eliminate or minimize by dissolving carbon dioxide in the water spray. The heat transfer analysis indicates that the heat removal rate steps up with the increment in carbon dioxide concentration up to 8 gm/litre soda concentration in water and a further rise in carbon dioxide concentration, quenching rate declines. The droplet impact mapping and the film boiling analysis corroborate the aforesaid results. The evaporation experiment also supports above findings and indicates unalteration of boiling point. The spray cooling result shows 37% enhancement in critical heat flux (CHF from 1.2 MW/m2 to 1.67 MW/m2) at 8 gm/litre soda concentration in water. The comparison of the critical heat flux with the results reported in the literature clearly asserts the suitability of the current methodology for the fast cooling operation.

Spray cooling of hot steel plate using aqueous solution of surfactant and polymer

In the current work, authors have performed extensive spray cooling experiments on a 6 mm thick hot stainless steel plate (>900 °C). The work has been separated into two distinctive parts. The first part involves optimization of water flow rate and spray impingement height based on maximum surface cooling rate and heat flux value. The highest cooling rate and heat flux of 133.7 °C/s and 2.21 MW/m2 were attained for a water flow rate of 16 lpm and impingement height of 6 cm. In the second part, different surfactants (cationic, CTAB; anionic, SDS; non-ionic, Tween 20), and polymer (PVP, water soluble) were added in to the water to study its impact on heat transfer parameters such as surface cooling rate, heat flux, and heat transfer coefficient. Amongst all the additives, the maximum enhancement in cooling rate and critical heat flux was achieved for non-ionic (Tween 20) based water solution which is 25.6% (168.2 °C/s) and 19.91% (2.65 MW/m2) higher than what had been attained by water spray. High speed photography was used at a lower temperature to visualize a single droplet impact and to understand the effect of surface tension and underlying physics on the heat transfer phenomenon. This study revealed that upon impingement, surfactant and polymer added drops disintegrate into multiple drops, increasing the overall contact area, and thereby enhancing the heat transfer rate.

Influence of Cu Addition on Microstructure and Mechanical Properties of Fe-0.08C-1Mn-2.5Ni Steel

In addition to precipitation strengthening effect as Cu precipitates in steel, Cu-containing steel is generally believed to have ability to resist corrosion. However, there are some issues, e.g. strengthening mechanism and appropriate copper content, remaining to be clarified. In this presentation, an offshore platform steel Fe-0.08C-1Mn-2.5Ni was used as experimental materials and the emphasis was put on the comparative study of Cu-addition in terms of microstructural evolution and mechanical properties by using microstructural characterization and mechanical properties measurement. The continuous cooling transformation behavior of the two Cu-containing steels with varying contents was first compared. The Cu-containing precipitates were then determined by transmission electron microscopy (TEM) in the hot rolled steel plate after quenching and tempering. Finally, the effect of Cu-addition on precipitation strengthening and low temperature toughness was discussed considering the interaction of Cu precipitates with dislocation and martensite microstructure.

Application of TiO2 nanofluid-based coolant for jet impingement quenching of a hot steel plate

ABSTRACTCooling rate in Run Out Table (ROT) in steel industries tailors microstructure which lead to improved mechanical properties. The current work aims to increase cooling performance of steel using TiO2 nanofluid as coolant in jet impingement. Different concentrations of TiO2 nanofluid have been used to study effect on jet cooling of a steel plate from 900°C. Thermal conductivity of nanofluid is found to significantly enhance at optimum concentration and this plays major role in increasing cooling rate of the steel plate. 19% enhancement in cooling rate is observed by using 40 ppm of TiO2 nanofluid compared to water.

OPTIMASI PEMILIHAN MATERIAL REAR AXLE HOUSING MODEL T8 JENIS TRUK KAPASITAS 7,5 TON

Truk adalah jenis transportasi yang banyak digunakan untuk mengangkut muatan baik hasilpertanian, perkebunan, pertambangan dan lain sebagainya. Ada beberapa varian kapasitas truk yang selamaini dibuat oleh pabrik. Salah satunya truk dengan kapasitas 7,5 ton. Masalah yang timbul adalah trukmengalami patah di bagian rear axlenya. Dengan metode elemen hingga untuk menganalisa desain kekuatanrear axle housing yang menggunakan material Hot Rolled Steel Plate dengan ketebalan 8mm danmenggunakan software pro-engineer didapat tegangan von mises 158,5 Mpa, Displacement 0,307mm danstrain max 0,000835mm dengan angka keamanan sebesar 5,29

Synthesis of Cu-Al LDH nanofluid and its application in spray cooling heat transfer of a hot steel plate

In the current study, authors have synthesized Cu-Al Layered Double Hydroxide nanofluid at different molar ratios of Cu and Al by using co-precipitation technique and utilized this as a coolant in a pressure atomized spray to achieve high cooling rates in the temperature range of 900–600 °C for a 6 mm thick steel plate. The study initially focuses on the effect of Cu: Al molar ratio variation on thermal conductivity, stability as well as its heat transfer potential in steel quenching. Post thermal conductivity and stability analysis, spray cooling experiments were conducted in two parts. The first part involves optimization of Cu: Al molar ratio by varying the ratio (Cu: Al = 2:1, 4:1 and 6:1) at a fixed nanofluid concentration (120 ppm) to select the best Cu: Al molar ratio based on heat transfer results. The results show that the highest cooling rate and average heat flux were achieved at a Cu and Al molar ratio of 4:1 among all molar ratio combinations. Once, the optimized molar ratio is selected, the second part of the spray cooling experiments was performed to study the effect of nanofluid concentration variation (40–240 ppm, at an optimized molar ratio of Cu: Al = 4:1) on spray cooling results. With respect to concentration optimization, the maximum cooling rate of 168.6 °C/s was attained at a concentration of 160 ppm which is 26% higher than what was achieved by normal water spray. Results obtained from the spray cooling experiments were further verified by the thermal conductivity analysis where highest enhancement of 15.17% was also observed at 160 ppm nanofluid concentration.