Coefficient Of Steel Research Articles

Estimation of structural steel and concrete stocks and flows at urban scale–towards a prospective circular economy

Quantification of stocks and flows of construction materials is a key first stage in assessing the potential for creating higher value at end-of-life decisions compared to destructive demolition. Steel and concrete are amongst the most widely used construction materials primarily in structural components. Such components are highly variable in design, type, and dimensions. In the absence of urban-scale digitised models of structural components or building plans, accurate assessment relies on either onsite inspection or modelling by material intensity (MI) co-efficient which can vary by up to a factor of 100. In this study, we extend previous stock modelling approaches through the development of a method that relies on building archetypes and produces MI coefficients of steel and concrete that are representative of frame types, temporally explicit and disaggregated at product level. This is compared to the common existent method of calculating MI to demonstrate the capabilities of the proposed method. Coupled with a spatiotemporal model of urban buildings, the developed MI of both methods are applied to a case study in the UK. The total in-use stock of steel and concrete within multi-storey buildings is estimated at 81,000 tonnes and 655,000 m3 respectively. The stocks of steel and concrete are disaggregated based on their functions as products, for instance steel beams are distinguished from reinforcement steel. Subsequently, the embodied carbon of the in-use stock is calculated as 350 kt CO2eq. The results show the proposed method enables a more granular assessment of the embodied carbon of the structural material quantities.

Tribotechnical Characteristics of Nanomodifier 1

The results of studies on the friction coefficient in steel, bronze, and cast iron friction pairs under the conditions of lubrication are presented. Comparative testing of the tribotechnical properties of motor oil without and with the addition of a specialized additive using a UMT-1 universal friction machine has been performed. The analysis of the results has demonstrated a narrow efficiency range of the additive in steel–cast iron and cast iron–bronze friction pairs upon introduction into motor oil.

Determination of Photon Attenuation Coefficients of Steel Doped Barite Plasters

The plaster is used as a flattening of the interior and exterior surfaces of the buildings and as decorative material. In this study, photon attenuation coefficients of barite plaster containing steel were measured. The measurements performed at 511, 835 and 1275 keV which are obtained from 22Na and 54Mn radioactive sources, using a gamma spectrometer that contains a NaI(Tl) detector and MCA. The measured results were compared with the calculation obtained using computer code of XCOM for 1 keV–1 GeV gamma energies. Also, half value layer (HVL) and tenth value layer (TVL) were calculated using the results obtained from the experimental measurement.

Development of a Reliable Kinetic Model for Ladle Refining

Kinetic modeling of ladle refining can be used by steel plants to improve steelmaking and to produce cleaner steels. It can also help researchers to understand the process better. There have been several recent attempts to develop a kinetic model that can predict changes in steel, slag, and inclusion compositions with time. Often the models require parameters that can be difficult to measure under plant conditions, and model limitations have not been discussed in detail. In this study, a two-parameter kinetic model has been developed to predict changes in steel, slag, and inclusion compositions during ladle refining; the two parameters are the mass-transfer coefficient in steel and the inclusion flotation rate constant. The model was based on FactSage macro-processing. Examples of results show that the model can be used to diagnose effects of steel and slag sampling practices and to estimate alloy dissolution time. The model results demonstrate that the presence of solids in slag can significantly reduce the rate of steel–slag reaction while maintaining a high inclusion flotation rate. Some limitations of the model are discussed: the overprediction of calcium transfer to alumina inclusions and the absence of information on inclusions originating from entrained slag.

Binder mediated enhanced surface adhesion of cured dry solid lubricant on bearing steel for significant friction and wear reduction under high contact pressure

A new thermally cured polymer-graphene-zinc oxide-based solid lubricant is developed that reduces friction and wear significantly during the sliding wear of bearing steel under extreme contact pressure and long duration. The dry solid coating composite was made from a mixture of graphene, zinc oxide, and a specific industrial binder and then laminated on the surface of 52100 steel disks using the spin-coating technique. A ball-on-disk apparatus set to 1 GPa Hertzian pressure and a sliding distance of 500 m was used to examine the tribological properties of the coating. After ∼3000 cycles, the 15 μm thick coating created a significant reduction in the steel's coefficient of friction (approximately 82%) and wear loss compared to the uncoated surfaces. Following the triboligical examination, scanning electron microscopy, energy dispersive X-ray spectroscopy, X-ray diffraction, and Raman spectroscopy were conducted to determine the topography and morphology of the composite coating and resultant wear scars. It is revealed that the persistent protective coating on the disk surfaces was attributed to the adhesion influence of interfacial zinc oxide and graphene on the contact surfaces. Scratch testing of the new composite demonstrated a significant improvement in its adhesive properties on bulk interfacial surfaces compared to previously studied coatings.

Effect of Direct Reduced Iron on Ferrous Oxide Capacity of Slag in Electric Arc Furnace.

Slag and the corresponding hot metal samples were collected just before tapping from electric arc furnace of Ezz Flat Steel Company (EFS) and analyzed. The temperature of hot metal was measured before tapping.The analyses of slag and hot metal together with the metal temperature were used to estimate the activity coefficient and activity of total ferrous oxides in slag, also investigate carbon and oxygen activity coefficient in steel according to the statistical theory of regular ionic solutions.The oxides capacity of the slag was also assessed. The variation of carbon and oxygen activity in hot metal with the concentration was also treated.The ratio of activity to concentration of total ferrous oxides is constant and equal to 0.0179. The activity coefficients of oxygen and carbon in steel are 0.810 and 1.0704, respectively.The oxides capacity of the slag increases with increasing carbon concentration in the bath and with increasing DRI proportion in the charge.

Thermal tests of large recirculation cooling installations for nuclear power plants

The article presents the results from thermal tests of some recirculation installations for cooling air in nuclear power plant premises, including the volume under the containment. The cooling effect in such installations is produced by pumping water through their heat-transfer tubes. Air from the cooled room is blown by a fan through a bundle of transversely finned tubes and is removed to the same room after having been cooled. The finning of tubes used in the tested installations was made of Grade 08Kh18N10T and Grade 08Kh18N10 stainless steels or Grade AD1 aluminum. Steel fins were attached to the tube over their entire length by means of high-frequency welding. Aluminum fins were extruded on a lathe from the external tube sheath into which a steel tube had preliminarily been placed. Although the fin extrusion operation was accompanied by pressing the sheath inner part to the steel tube, tight contact between them over the entire surface was not fully achieved. In view of this, the air gap’s thermal resistance coefficient was introduced in calculating the heat transfer between the heat-transferring media. The air gap average thickness was determined from the test results taking into account the gap variation with temperature due to different linear expansion coefficients of steel and aluminum. These tests, which are part of the acceptance tests of the considered installations, were carried out at the NPO TsKTI test facility and were mainly aimed at checking if the obtained thermal characteristics were consistent with the values calculated according to the standard recommendations with introduction, if necessary, of modifications to those recommendations.

Thermal stress measurement in steel plate strengthened by CFRP and aluminum alloy plates

In steel members strengthened by carbon-fiber reinforced polymer (CFRP) plates, the thermal stresses are introduced in the steel members, the CFRP plates and the adhesive layers when temperature changes because the linear thermal expansion coefficients of steel and CFRP are mismatched. As so far, the authors proposed a technique to reduce the thermal stress in steel members strengthened by CFRP plates, which involves bonding aluminum alloy plates with CFRP plates. In the proposed method, the thermal stress in steel member can be reduced so that there are negligible levels of stress in steel member when the cross sectional areas of CFRP and aluminum plates are designed to correspond to the coefficient of thermal expansion of steel, even though the thermal stresses are introduced in the CFRP and aluminum plates. In this study, to confirm the maintaining the thermal stress reduction in steel member by proposed method, thermal stress measurement in steel plate strengthened by CFRP and aluminum plates was carried out about 21 months. In this research, the thermal stress introduced in the steel plate strengthened by CFRP plates was also measured. Furthermore, to assume the thermal shear and normal (peel) stresses in adhesive layers, FE analysis with plane stress element was employed. As the result, it was shown the thermal stresses in steel plate with CFRP plate were able to calculate by using composite theory and measured temperature. Furthermore, in steel plate strengthened by CFRP and aluminum plates, the thermal stress introduced in steel plate was negligible-small through the all-season. It was found the thermal stresses in steel plate with CFRP plates as well as CFRP and aluminum plates were also estimated by using composite theory and measured temperature. In the steel plate strengthened by CFRP and aluminum plates, the thermal shear and normal stresses in adhesive layer glued to steel plate become smaller than that in the conventional CFRP bonded specimen. However, the shear stress in adhesive layers between CFRP and aluminum plates in proposed method was higher than the thermal stress in adhesive layers between CFRP plates in conventional method.

MCNP Modeling of Attenuation Coefficients of Steel, Red brass, Pearl and Beryl in comparison with Experimental and XCOM Data

In this research, MCNP model for studying mass attenuations coefficients for steel, Red brass, Pearl and Beryl at 661.6, 1173.2 and 1332.5 keV photon energies is investigated. The simulated results of mass attenuation coefficients were compared with the experimental and XCOM results. The results indicate that this process can be followed to determine the data on the attenuation of gamma rays with the several energies in different materials. The modeling for photon interaction parameters was standard for any type of composite samples.

Research of Axially Loaded Steel Columns Reinforced under Load

With the lapse of time, the carrying capacity of early steel structure buildings which affected by various factors in the process of long service has dropped. Meanwhile, the use function of buildings has been asked for a higher level with the improvement of people's living standard. In this case, the assessment and reinforcement on buildings are particularly important. In this paper, the characteristics and mechanical properties of axially loaded steel columns strengthened by welding under load and axially loaded steel columns strengthened by enclosed reinforced concrete under load, the mechanism of steel and concrete work together and the reduction coefficients of steel and concrete of enclosed reinforced concrete have been systemically introduced. To pave the way for the following researches of steel numbers reinforced under load.

Novel method for determining the dynamic friction coefficient of explosives

A new method for determining the dynamic friction coefficient of explosives is presented. The method combines the physical model of friction sensitivity with theoretical analysis and numerical calculations. Experimental measurements of the dynamic friction coefficient of steel indicate that the proposed method is effective, provides secure and reliable data, and can be used to calculate the dynamic friction coefficient between cyclonite (RDX) and steel.

Effect of Grain Boundary Segregation of Interstitial Elements on Hall–Petch Coefficient in Steels

The yielding behavior of interstitial-free steels and low-carbon steels with varying amounts of C and N were investigated in connection with the Hall­Petch relation. The Hall­Petch coefficient is as small as 150MPa·µm 1/2 in interstitial-free steels but it increases to 600MPa·µm 1/2 by adding solute carbon up to 60ppm. Nitrogen does not have a significant effect on the Hall­Petch coefficient. The results of three-dimensional (3D) atom probe analysis indicated that carbon has 3­4 times greater segregation potential in comparison with nitrogen. The small effect of nitrogen on the Hall­Petch coefficient in steel is probably due to the small segregation potential of nitrogen. It was also confirmed that discontinuous yielding occurs when the difference between the yield stress and friction stress is increased by grain-refinement strengthening and that yielding occurs by dislocation emission from grain boundaries where primary dislocations have piled up. Carbon atoms segregated at grain boundaries seem to play a role in stabilizing dislocation emission sites at the grain boundaries, which enhances the Hall­Petch coefficient of iron. These results support the dislocation pile-up model of explaining yielding in polycrystalline metals. [doi:10.2320/matertrans.MA201314]

Research on the Folding and Deploying Mechanism with Analysis of Frictional Coefficient of Steel and Aerodynamic Resistance

In this article the folding and deploying mechanism is researched, the equivalent dynamical model is built, and the configuration of the folding and deploying mechanism is designed including the folding mechanism, the deploying mechanism and the locked mechanism. This paper obtains the athletic rule of folding and deploying mechanism, then analyses the dynamic time of the folding and deploying mechanism and the reliability of the locked mechanism, also analyses of frictional coefficient of the steel and aerodynamic resistance of the mechanics.

Stress-dependent changes in the diffuse ultrasonic backscatter coefficient in steel: Experimental results

In this article, the effects of uniaxial compressive loading on the ultrasonic scattering from polycrystalline grains are shown for 10 MHz ultrasound in annealed, 1018 steel. The results show a decreasing value of the stress-dependent backscatter coefficient for normal incident ultrasound when the compression loading is perpendicular to the scattering direction. The change due to scattering is about 2 orders of magnitude greater than changes observed by others using ultrasonic wavespeed measurements. It is anticipated that this research can serve as the basis for many methods associated with nondestructive determination of stress in structural materials.

Study on Displacement Ductility Coefficient of Steel Reinforced High-Strength Concrete Column

In order to study the displacement ductility coefficient of steel reinforced high-strength concrete column, 23 groups of components with various design parameters were tested and related factors that affect the displacement ductility coefficient of SRHSC column were presented in this paper. The proposed formula for calculating the displacement ductility coefficient of SRHSC column can be obtained from the multivariate nonlinear regression of test results by using SPSS. The calculation results agree well with the test conclusions, and it shown that the proposed formulas own high accurateness and can be objectively reflect the mechanical behavior of SRHSC column root. The research achievements will provide a theoretical support for the design of SRHSC column.

Automated Determination and On-Line Correction of Emissivity Coefficient in Controlled Cooling of Drop Forgings

The paper presents the methodology of determination of emissivity coefficient of steel in the direct cooling temperature range, which allow self-definition of this parameter in automated temperature control system used for direct cooling of drop-forged parts. Based on the actual temperature of the surface of the workpiece, the system automatically adjusts the velocity of fan-forced air to produce desired cooling rate and course of cooling curves. To enable automatic correction of cooling rate, the system must rely on exact remote temperature measurements. This is conditioned by correct definition of emissivity in pyrometer gauge system. Traditionally, pyrometers use presets of a constant value, selected as to get optimum consistency for the temperature range concerned. As the emissivity is time-dependent, the idea of the approach presented in the paper is to use time dependent characteristics, to attain the minimum discrepancy between actual and measured values during the whole cooling cycle.

Phase transitions in surface layers of polycrystalline solids

The fundamental equations of the thermodynamics of films were applied to describe the properties of polycrystalline solids, namely, first-order phase transitions of grain boundaries with the formation of two-dimensional liquids. The generalized equation obtained was used to calculate the temperature of this phase transition (the premelting temperature) for metals; it was found to lie between 0.55 and 0.86 of the temperature of fusion. The experimental nitrogen diffusion coefficient in steel over this temperature range was the same as in liquid steel.

Makro- und Mikrosegregation beim Dünnbandgießen von Fe-Si-Legierungen nach dem Zwei-Rollen-Verfahren / Macro- and Microsegregation of Fe-Si Thin Strips Produced by a Twin-Roll Continuous Casting Process

The negative segregation of components with a distribution coefficient in steel of less than one observed in the casting of thin strip using the twinroll process is due to a flow of the residual melt from the interdendritic regions. This occurs when the two solidified shells of the strip in contact with the cooling rolls meet under the combined influence of the rolling force and the localised suction caused by areas of the strip isolated by the formation of bridges. A rolling force which is not constant across the width of the strip leads to qualitative and quantitative differences in the macrosegregation occurring. The variation of the rolling force across the strip is in turn caused mainly by the irregular progression of the solidification front under the influence of forced convection

Vacuum Carburizing of Low Carbon Steel with Methane

On low carbon steel specimens vacuum carburized at temperatures in the range from 1193 to 1313 K in a methane atmosphere at pressures ranging from 13 to 80 kPa, carbon content profiles within the specimens were determined from a succession of grindings and carbon analyses with a vaccum type emission spectrometer. The total amount of carbon which entered each specimen through the surface during a carburizing period was graphically calculated from the profile, and the rate of carburizing was evaluated from the amount of carbon. It was found that the rate of vacuum carburizing with methane had the temperature dependence several times as strong as that of gas carburizing. A mathematical model for calculation of such carbon content profiles is presented. The model in which the variation of carbon diffusion coefficient in steel with carbon content was taken into consideration predicted accurately the surface carbon content and case depth of vacuum carburized steel.

Physical Properties of Compact Cyclotron Produced Fast Neutron Fields

A number of physical properties of the fast neutron fields produced when 8 MeV deuterons or 23 MeV ${}^{3}{\rm He}$ ions are incident upon a thick beryllium target have been measured. These include the relative angular dose distributions, the linear dose attenuation coefficients of steel, lead, and a polyethylene mixture, depth dependence of the total dose, the gamma-ray dose and the neutron planar fluence, and the distribution of dose in linear energy transfer at various positions in the fields.