Rolled Steel Sheets Research Articles

Nonlinear PID actuator speed control in inverter based electro-hydraulic systems subjected to external leakage

ABSTRACT Actuators of constant speed operation in hydraulic power systems are highly required in many applications such as steel sheet rolling and pressing operations. To achieve this, a variable pump and/or control valve may be used to control the actuator speed in different operating conditions. A mathematical model of the selected hydraulic system and its components has been carried out using SIMULINK to study its static and dynamic characteristics. A direct comparison between the mathematical model results and experimental results of the same hydraulic system published by the author has been introduced. For the experimental and the mathematical models, a linear and nonlinear PID control algorithm has been applied for pump speed control and proportional directional control valve in the presence of system disturbance, herein is an external leakage, to maintain the actuator velocity constant either by controlling the pump speed or the proportional directional control valve with achieving the minimum error. The nonlinear control PID showed a better system response than the PID controller and reduced the error hence improved the system response. It has been shown that the proportional valve control is better than the pump speed control for different external leakage, 5–10%, with an error of the order 3% from the setting velocity.

Effects of the residual stress, interfacial roughness and scale thickness on the spallation of oxide scale grown on hot rolled steel sheet

Failure at the interface between a steel substrate and oxide scale was investigated by semi-analytical and finite element numerical simulations. Two major stress components along the interface, i.e., tensile normal stress at the peak and shear stress at the inflection point of the idealized undulated interface, were calculated and used for the failure analysis. The mechanical properties of the oxide scale and steel substrate were experimentally measured by the indentation and uniaxial tensile tests, respectively. Growth and thermal residual stresses accumulated at the oxide scale during cooling were calculated by a coupled numerical-analytical method, which was experimentally validated by measuring the residual stresses in the oxide scales with different thicknesses. The finite element simulation of a four-point bending test was conducted in order to reproduce uncoiling process during which spallation of oxide scale may occur. From the analysis of the simulation results, the two major stress components turned out to be amplified by the roughness of the interface and the residual stresses generated by the growth stress of oxide scale and the thermal mismatch between the oxide and steel substrate during cooling. In addition, the shear stress proved to be a significant factor for the spallation behavior. The effect of scale thickness on the spallation was discussed by using the concept of failure map based on interfacial fracture energy.

Monitoring of process performance by means of financial indicators

The paper deals with problematic nature of measuring of process performance. It includes a designed procedure of process performance monitoring, evaluation of logistic processes quality, and also measuring of the impact of marketing activities on the profitability of process output, i.e. a product, by means of appropriate indicator.There are several performance indicators that companies use to monitor the performance of their processes and business strategies with respect to their objectives. To monitor these indicators, enterprises rely on dashboards that present one or more indicators along with contextual information to help decision makers identify deviations and their root causes. Associated benefits related to the process performance measurement system can be seen, for example, in better decision-making, flexible human resource management and process management structures. By using rolled steel sheets in a large metallurgical plant as an example, there will be shown how the performance of the rolling process can be improved by monitoring the tangible financial indicator. Subsequently, the experience was from case management companies presented to further incorporate a practical view of implementation and related issues. Finally, the reasons why the organization prefers the observed indicator during implementation of the process performance of measurement system is explored in order to understand the causes and consequences.

Performance of turmeric dryer cabinets with LPG fuel using temperature control and air speed

There is a huge potential of turmeric to be processed into various kinds of medicines or food products as there are still many people consuming traditional medicines and beverages for their health. Thisleads to the need of a clean raw turmeric processing, in spite of the fact that turmeric commodity grown in the high lands. The process of direct turmeric drying can not be maximal because of the low solar intensity caused by cloudy weather. If the drying process continues to constantly produce 12% water level, the turmeric medium will be damaged due to fungus arise on the surface of turmeric influenced by high humidity factor. Therefore a closed turmeric dryer with LPG fuel at a low cost is made. Using ST 37 material for the construction frame, while the inner cover uses stainless steel, and for the outside cover uses hot rolled steel sheet material. In addition, the dryer used can be controlled by air velocity and temperature in the drying cabinet and equipped with transparent glass to see the physical state of the turmeric inside. Obtained temperature during experiment is 50-550C in average with drying duration of 60 minutes with 0,15 m / s air speed and the water level obtained is 12% with the efficiency degree equal to 59%.

Micromechanical Modeling of DP600 and DP800 Steels Plastic Behavior Based on the Mori-Tanaka Homogenization Method

The properties of the dual-phase steels are attributed to the chemical composition, type, size, amount, and spatial distribution of different phases that can be obtained during thermomechanical treatments. In this way, modeling of the mechanical behavior of the dual-phase steel constituents, namely, ferrite and martensite, is crucial to the numerical simulation of sheet metal forming processes mainly to forecast the residual stresses per phase. In this work, the microstructure of as-received DP600 and DP800 cold rolled steel sheets with 1.2 mm nominal thickness were firstly characterized by means of scanning electron microscopy technique. The grain sizes and volume fractions of ferrite and martensite phases were obtained by means of digital image analysis. The Mori-Tanaka homogenization scheme was implemented in the finite element code ABAQUS assuming linear isotropic elasticity and isotropic work-hardening behavior for both ferrite (matrix) and martensite (inclusion) phases. The numerical predictions obtained with the Mori-Tanaka homogenization scheme for the macroscopic uniaxial tensile behavior are in good agreement with the experimental curves of both dual-phase steels.

Micromechanical Modeling of Dual-Phase DP600 Steel Sheet Plastic Behavior Based on a Representative Volume Element Defined from the Real Microstructure

Dual-phase steels offer very attractive combinations of strength and ductility owing to the coexistence of different microstructures components and their interactions. These steels are suitable to the automotive industry due to their improved impact resistance increasing the passenger safety along with the vehicle weight reduction. The properties of the dual-phase steels are attributed to the chemical composition, type, size, amount and spatial distribution of different phases that can be obtained during thermomechanical treatments, namely, ferrite and martensite. In this work, the microstructure of as-received DP600 cold rolled steel sheet with 1.2 mm nominal thickness was firstly characterized by means of scanning electron microscopy technique. Then, a representative volume element was obtained from the DP600 microstructure and a micromechanical finite element model is proposed considering the steel chemical composition, average ferrite grain size, martensite volume fraction and mechanical properties of both ferrite and martensite phases. The uniaxial tension loading was simulated by assuming either plane-stress and plane-strain conditions. The numerical predictions corresponding to the plane-strain model are in good agreement with the experimental true stress-strain curve determined along the sheet rolling direction. The proposed finite element micromechanical approach based on the real microstructure proved to be an important tool to evaluate both local and overall behaviors of DP600 steel grade.

Polystyrene and cornstarch anti-corrosive coatings on steel

Abstract This work aims to evaluate the performance of anticorrosive thermoplastic coatings in cold rolled steel sheets. Two types of thermoplastic coatings were studied: polystyrene (PS) and cornstarch. These types of coatings are applied for protection against corrosion during transport and storage of steel plates after cold rolling until delivery to stamping or other processing. The good performance for these coatings is suitably standardized to ABNT NBR 5915-2: 2013 and ASTM A1008 / A1008M-2016. According to corrosion tests carried out in saline chamber, the coatings were satisfactory in different degrees of guarantee of corrosion protection on ASTM 1080 steel, in accordance with standards mentioned.

Influence of zinc coating on anisotropic mechanical properties of hot dip galvanized steel sheet DP600

The influence of zinc coating on the anisotropic mechanical properties of hot dip galvanized steel sheet DP600 is studied by tensile test. The results show that zinc coating makes the yield strength of the steel plate decrease, but has no obvious influence on the hardening index. Compared with the bare steel sheet, in the direction of R00 direction parallel to the rolling direction, the tensile strength and yield strength of galvanized steel sheet decrease, while the elongation and thickness anisotropy coefficient increase. After comprehensive analysis, it is found that the plastic deformation ability has decreased in the direction of R00 direction. and the plastic deformation ability decreases after comprehensive analysis. In the R90 direction, the mechanical property parameters of galvanized sheet all increased, and zinc coating improves the plastic deformation ability of the steel sheet. However, in the R45 direction, the variation extent of the mechanical property parameters of galvanized steel sheet is between R00 and R90. Therefore, the influence of zinc coating on the mechanical properties of steel plate is closely related with the rolling direction, which also illustrates that the adhesion strength between the galvanized layer and steel plate substrate is affected by the surface microstructure of rolled steel sheet.

Numerical Simulation of Cold Rolled Steel Sheet Metal during Blanking Process

Numerical Simulation of Cold Rolled Steel Sheet Metal during Blanking Process

Austenite transformation simulation for a controlled rolling processing technology development

Abstract Using an originally-developed computer model and appropriate software the impact of deformation on austenite phase transformation in low carbon alloyed steel was carried out. The computer simulation takes into account an impact of the deformation degree and takes into account non-constant cooling rate. That makes it useful for the development of thermal and deformation technological processes development. Based on the simulation results a technology of controlled rolling of low carbon steel alloyed by carbide forming elements (Nb, V, Ti) was developed. The proposed technique allows production of rolled steel sheets with high strength and plastic properties, as well as high impact strength in normal and low temperatures.

Corrosion-protective reduced graphene oxide coated cold rolled steel prepared using industrial setup: A study of protocol feasibility for commercial production

A process for the production of reduced graphene oxide (rGO) coated cold rolled steel (CRS) sheet using an industrial setup is developed and its electrochemical properties are studied. The electrochemical data reveals that rGO coating followed by a layer of sunflower oil (SO) coating suppresses the corrosion rate by ~10,000 times than the bare CRS sheet in 3.5 wt% NaCl aqueous solution. Further, the long term EIS study verifies the superiority of the layer-by-layer coating over SO coated CRS sheet. Such significant corrosion protection of the coating is attributed to the barrier effect of rGO.

New Process for the Goss Texture Formation and Magnetic Property in Silicon Steel Sheet by Hot Asymmetric Rolling and Annealing

The shear deformation texture of bcc metals is characterized by the Goss orientation, or {110}〈001〉, which is a highly useful orientation for grain-oriented silicon steels because it gives rise to high magnetic permeability along the 〈100〉 direction. To obtain the Goss texture, or {110}〈001〉, in silicon steel sheets, a silicon steel sheet was subjected to an 89 pct reduction in thickness via asymmetric rolling at 750 °C. This step resulted in the well-developed Goss texture. When multiple asymmetrically rolled steel sheets were subsequently annealed, one at 900 °C for 1 hour and the other at 1200 °C for a short period of 5 minutes in a box furnace with air atmosphere, a strong Goss texture was developed in the silicon steel sheets. The texture was measured via X-ray diffraction and electron backscatter diffraction. The magnetization curve of each specimen was measured by the vibrating sample magnetometer and the measured magnetization curve showed the typical soft magnetic characteristics.

Goss Texture Formation by Asymmetric Rolling in Steel Sheet

The Goss texture, or {110}<001>, shows soft magnetic property due to the <100>. Therefore, it is one of the most important texture in Si steels. The Goss texture is one of the shear deformation texture in steel which has bcc structure. During the asymmetric rolling, shear deformation is imposed on steel sheets. To obtain the Goss texture, the carbon and Si steel sheets were asymmetrically rolled by 50-85% reduction in thickness at room temperature and at 770 °C. The asymmetric rolling of steel sheets gave rise to the well-developed Goss texture to them.

Effect of Thin Polymer Coatings on the Mechanical Properties of Steel Plates

The influence of powder coatings based on an epoxide polyester mixture on the mechanical properties of the plates made of rolled sheet steel is studied. The influence of 100-μm-thick coatings on the mechanical properties of specimens 0.7–1.5 mm thick is considered. The bending and tensile tests performed at room and elevated temperatures show that the thin coatings weakly affect the mechanical properties of the plates. In particular, the stiffness of the coated plates during tension and bending remains almost the same despite the fact that the elastic modulus of the coated plates is always slightly lower than Young’s modulus of steel because of an increased specimen thickness determined with allowance for the presence of a coating. The influence of the coatings is substantial in compressive stability tests. Under supercritical deformation conditions, the bearing capacity of the coated plates decreases substantially, and their critical stability load on the loss of stability falls by 20–30% (depending on the substrate thickness). This effect can be explained by the influence of the residual thermal stresses that appear in the specimens during coating deposition.

Effect of Tailoring Martensite Shape and Spatial Distribution on Tensile Deformation Characteristics of Dual Phase Steels

The authors simulated the industrially used continuous annealing conditions to process dual phase (DP) steels by using a custom designed annealing simulator. Sixty-seven percentage of cold rolled steel sheets was subjected to different processing routes, including the conventional continuous annealing line (CAL), intercritical annealing (ICA), and thermal cycling (TC), to investigate the effect of change in volume fraction, shape, and spatial distribution of martensite on tensile deformation characteristics of DP steels. Annealing parameters were derived using commercial software, including thermo-calc, jmat-pro, and dictra. Through selection of appropriate process parameters, the authors found out possibilities of significantly altering the volume fraction, morphology, and grain size distribution of martensite phase. These constituent variations showed a strong influence on tensile properties of DP steels. It was observed that TC route modified the martensite morphology from the typical lath type to in-grain globular/oblong type and significantly reduced the martensite grain size. This route improved the strength–ductility combination from 590 MPa–33% (obtained through CAL route) to 660 MPa–30%. Finally, the underlying mechanisms of crack initiation/void formation, etc., in different DP microstructures were discussed.

Production of thick steel sheet for high-pressure equipment operating at temperatures from 450°C to–50°C

The industrial production of low-carbon microalloyed steel plates (thickness 150–200 mm) on the NLMK Dansteel 420 reversible rolling mill is considered. Such plates are intended for operation at temperatures between–50 and +450°C in high-pressure equipment. The technologies used for steel casting and thick-sheet production ensure stable strength over the whole sheet thickness at 20–450°C, with satisfactory impact strength between +40 and–50°C. The research results are used in certification on the basis of TUV Pressure Equipment Directive (PED) DGR 2014/68/EU and the AD2000 directive regarding the production of rolled P355N, P355NH, P355NL1, and P355NL2 steel sheet of thickness up to 200 mm.

Achieving optimized tungsten inert gas butt welding conditions of thin cold rolled steel sheets by response surface methodology and artificial neural networks

This paper describes the multiresponse optimization of tungsten inert gas welding for an optimal parametric combination to predict the weld characteristics of thin cold rolled steel sheets. The interaction effects of tungsten inert gas welding process parameters such as welding current, arc length, and traverse speed have been observed on the weld characteristic responses such as weld width, heat-affected zone width, and under-bead depression. Full factorial design of experiment was followed for determining the combinations of the experimental runs. Regression analysis was carried out to develop the mathematical models for the welding control factors and responses. Analysis of variance was used to check the adequacy of the developed mathematical model. The confirmatory tests were conducted to validate the accuracy of mathematical model. Sensitivity analysis was also done to analyze the effect of each individual process parameter on the weld responses. The full factorial experimental data was further utilized for multi-response optimization of the tungsten inert gas process parameters. It was observed that weld responses like weld width and heat-affected zone width could be optimized by regression modeling technique while the under-bead depression showed uncertain behavior. The under-bead depression ranged from 0.0 to 0.15 mm and was observed only when the arc traverse speed was at the lowest level (4 cm/min) for all values of the welding current and arc length. The experimental data were also modeled using the artificial neural network technique for the prediction of weld responses and the results were compared with that from the regression analysis.

Finger pad friction and tactile perception of laser treated, stamped and cold rolled micro-structured stainless steel sheet surfaces

Tactile perception is a complex system, which depends on frictional interactions between skin and counter-body. The contact mechanics of tactile friction is governed by many factors such as the state and properties of skin and counter-body. In order to discover the connection between perception and tactile friction on textured stainless steel sheets, both perception experiments (subjective) and tactile friction measurements (objective) were performed in this research. The perception experiments were carried out by using a panel test method to identify the perceived roughness, perceived stickiness and comfort level from the participants. For the friction experiments, tactile friction was measured by a multi-axis force/torque transducer in vivo. The perceived stickiness was illustrated as an effective subjective stimulus, which has a negative correlation to the comfort perception. No significant evidence was revealed to the connection between the perceived roughness and comfort perception, and this relationship may be influenced by the participants’ individual experience, gender and moisture level of skin. Furthermore, the kinetic tactile friction was concluded as an objective stimulus to the comfort perception with a negative correlation.

A Novel Texture Improving Young’s Modulus in Rolling Direction of Hot Rolled Low Carbon Sheet Steel

A novel texture, which improves Young’s modulus in rolling direction, has been found in a hot rolled low carbon sheet steel. This unique texture is observed in sheet surface area, which consists of sharply developed {110}<111>–{110}<112> fiber without {110}<001>. Together with {112}<111> orientation, this fiber can significantly contribute to increase Young’s modulus in rolling direction. The measured Young’s modulus in rolling direction in the present material is 236 GPa, which is more than 10% increase, compared to the one in conventional steels.

Plasticity of Flat Bars in Platform Gratings

The aim of the paper is to study the difference in the Re yield point and the ultimate Rm tensile strength in steel-sheet S235JR, samples taken from the outer and middle part of the top layer and the inner part of the circle. The mentioned material characteristics determine the bearing capacity and the stiffness of platform gratings of a certain construction. The samples were cut out at 0°, 45°, and 90° angles in relation to the steel-sheet rolling direction. The differences in the Re and Rm values may be due to non-identical steel-sheet cooling times in different areas of the circle and the strain hardening of the pieces during flattening. The chemical composition and the structure of the flat bars were studied.