Properties Of Hot-rolled Strips Research Articles

Metallographic structure improvement of hot rolled strip induced by high temperature diffusion of MoS2 nano-lubricant

To improve metallographic structures and lubricating properties of hot rolled strips, a multifunctional MoS2 nano-lubricant was proposed for hot rolling process. Through hot rolling tests and relevant characterization methods of energy dispersive spectrometer (EDS) and field-emission scanning electron microscopy (FESEM), the multifunctional MoS2 nano-lubricant was proved to have both improved metallographic structures and lubricating properties. Not only the rolling forces were decreased, the thickness of oxidized scale was also reduced from 30–35 μm to 16–18 μm by using the MoS2 nano-lubricant. The grains in metallographic structure were observed to be refined obviously, and the orientations of pearlite lamellae were more multidirectional. There were also some carbide precipitates with dispersion strengthening effect appeared around grain boundary. The presence of Mo atoms within the iron matrix indicates the improved metallographic structure as a result of the diffusion of MoS2 nanosheets. This behavior is further instigated using thermal diffusion test, hot compression test, and molecular dynamics (MD) simulation. The results show that the metallographic structure improving effect of multifunctional MoS2 nano-lubricant was attributed to the interaction between MoS2 nanosheets and strips under the high-temperature and high-pressure condition of hot rolling process. In the presence of such high pressure, Mo atoms in MoS2 nanosheets could diffuse through the oxidized scale and exist in the iron matrix. The interaction between Fe and MoS2 nanosheets, meanwhile, was stronger. The diffused Mo atoms in iron matrix could form some coordination complexes with Fe atoms, which promote the nucleation of cementite, and playing a role in grain refinement. Therefore, the bifurcation growth was significantly enhanced, thus the growth directions of pearlite were also increased significantly. The researches provided not only theoretical basis for the development of multifunctional nano-lubricant with integrated metallographic structure improving effect, but also a new path for surface strengthening of strips.

Prediction of mechanical properties of hot rolled strips based on support vector quantile regression with adaptive QLASSO

Prediction of mechanical properties of hot rolled strips based on support vector quantile regression with adaptive QLASSO

Prediction of Mechanical Properties of Iron and Steel Based on the Quantile Model of Generalized Radial Basis Neural Network

Hot rolled steel is a material made by heating at high temperature. It has strong plasticity and is used in shipping industry, automobile industry, manufacturing industry, etc. Tensile strength refers to the maximum resistance to uniform plastic deformation of the material. It is an index of the mechanical properties of steel and determines the quality of steel to a certain extent. The influencing factors of tensile strength include steel processing parameters and chemical composition. As an improved model of RBF neural network, the generalized RBF neural network reduces the complexity of the model, improves the generalization ability of the model, and makes its application more extensive. In this paper, a generalized RBF neural network quantile regression model (QR-GRBFNN) is established to predict the mechanical properties of hot rolled strip, the mean percentage error (MAPE) and root mean square error (RMSE) are used as evaluation indexes. Experiments show that the model has better predictive performance.

Prediction of mechanical properties of hot rolled strip based on DBN and composite expectile regression

Prediction of mechanical properties of hot rolled strip based on DBN and composite expectile regression

Mathematical Modeling in View of Property Prediction of DD11 Steel Laminated in LBC Liberty Galati

The paper presents a mathematical model for predicting the mechanical properties of hot rolled strips. The realization of this mathematical model relied on statistical measurements of the mechanical properties (Rm, Rp0,2 and A5) for the laminated strip in the LBC rolling mill from the Liberty Steel Galati steel plant. To achieve this mathematical model, there has been used the active experiment method.By means of this mathematical model, significant time and material savings can be made in the process of testing the mechanical properties for hot rolled tape.

An intelligent online detection approach based on big data for mechanical properties of hot-rolled strip

An intelligent online detection approach based on big data for mechanical properties of hot-rolled strip

Prediction model based on XGBoost for mechanical properties of steel materials

In order to predict the mechanical properties of steel materials, an intelligent prediction approach based on XGBoost model and big data is presented in this paper. The effectiveness of the model was verified by using it to predict the mechanical properties of hot-rolled strips. Firstly, a dataset with 17,710 samples was established by using the practical hot-rolled process data, where every sample has 17 characteristics (C, Si, Mn, P, S, Alt, V, Ti, Nb, Ni, Cr, Cu, Mo, B, N, final rolling temperature and curling temperature) and three output variables (tensile strength, compressive strength and elongation). 90% of 17,710 samples were used as training samples and others were used as testing samples. The simulation results showed that the accuracy of the model for tensile strength, compressive strength and elongation of the hot-rolled strip was 0.99895, 0.99576, 0.96260, respectively, which were superior to the results by using BP neural network model.

Development of Hot Rolled Strips for Internal Plates of Automobile

The hot rolled strips for internal plates of automobile was developed by taking the technologies of low-carbon softening steel, including strictly control the chemical composition content during the steel melting and optimization of the rolling processes in the thin slab continuous casting and rolling line. The results showed that when carbon content was 0.04%, adding aluminum content or reducing silicon content and manganese content, reducing the reduction in previous rolling passes and increasing the reduction of the finishing pass at high temperature was beneficial for reducing the yield strength and tensile strength of the hot rolled strips. The precipitate of the samples after annealing showed that the precipitate of aluminum-nitride increased significantly at 850°C. And the texture of the samples after annealing showed that the main texture was {110} <001> and its intensity was 1.7-2.0, annealing with hot rolled strips did not benefit the advantageous texture. Tension-tension fatigue properties of hot rolled strips and cold rolled ones were determined, the results showed that the fatigue properties of hot rolling strips were rather higher than that of cold rolled ones. In the stamping experiments of some automobile parts, there was not any drawback, and the forming properties of hot rolling strips were equal to that of cold rolled ones. It was feasible to replace the cold rolled strips with the hot rolled ones for the internal plates of automobile.

Prediction of Mechanical Properties of Hot Rolled Strip by Using Semi-Parametric Single-Index Model

A semi-parametric single-index model based approach was proposed for prediction of mechanical properties of hot rolled strip. Based on industrial production data, a semi-parametric single-index model was developed by choosing the appropriate kernel function and window width to predict the yield strength, tensile strength and elongation. When data samples are limited, compared with regression method and neural network method, the prediction results show that the semi-parametric single-index model based method is more adaptive and the prediction performance is superior to those by both regression and neural network methods.

Fatigue Property of Hot Rolled and Cold Rolled Strips

Tension-tension fatigue properties of hot rolled and cold rolled strips with same contents and sizes were measured by using group test method at room temperature in air. The results showed that the fatigue properties of the hot rolled strips were obviously higher than those of the cold rolled strips. The hot rolled strips with similar or higher tensile strength exhibited superior fatigue property over the cold rolled strips. Fracture morphologies observed using scanning electronic microscope (SEM) showed that the hot rolled strips exhibited larger fracture areas, indicating a slightly lower plasticity, and more even fracture microstructure and stable properties. It is feasible and reliable to replace cold rolled strips with hot rolled strips.

A Knowledge-Based System for Temperature Prediction in Hot Strip Mills

Rolling temperature is an important factor affecting mechanical properties of hot rolled strip significantly. Traditional techniques cannot meet higher precision control imperatives. In the present work, a novel knowledge-based system has been developed for the temperature prediction in hot strip mills. Neural network has been used for this purpose, which is an intelligent technique that can solve nonlinear problem of temperature control by learning from the samples. Furthermore, an annealing robust learning algorithm was presented to adjust the hidden node parameters as well as the weights of the adaptive neural networks. Simulations in a multi-object mode have been carried out to verify the effectivity of new neural optimization system. Calculation results confirm the feasibility of this approach and show a good agreement with experimental values obtained from a steel plant.

Modeling of structure of double-phase low-carbon chromium steels

A physical model for determining the relative amount of phase components and the size of ferrite grains after decomposition of austenite in the process of cooling of double-phase steels is suggested. The main products of austenite transformation, i.e., polygonal ferrite, pearlite, bainite, and martensite, are considered. The driving forces of the transformation and the concentration of carbon on the phase surface are determined with the use of methods of computational thermodynamics. The model is based on equations of the classical theory of nucleation and growth. It allows for the structural features of the occurrence of γ → α transformation and contain some empirical parameters. The latter are determined using data of dilatometric measurements of the kinetics of austenite transformation and metallographic measurements of the size of ferrite grains. The model is used for predicting the kinetics of the transformation under the complex cooling conditions implemented by the VOEST-ALPINE STAHL LINZ GmbH rolling mill within the computer system for control of mechanical properties of hot-rolled strip.

Innovative developments by Siemens VAI in hot-rolling technology

In this paper, Siemens VAI presents its SmartCrown Technology package, which includes innovative solutions for the improvement of dimensional tolerances, of profil and flatness, and for the achievement of high mechanical properties of hot rolled strips. Steel producers can thus benefit from advantages in terms of product quality and cost.

Modelling effect of hot rolling process variables on microstructure and mechanical properties of low carbon strip steels

The microstructure and mechanical properties of hot rolled strip are determined by the chemical composition and the hot rolling process. Slab reheating temperature and time, roughing delivery temperature, finishing delivery temperature and coiling temperature are the four main variables to be controlled during hot rolling. In the present work a computer aided model has been developed, combining metallurgical phenomena and the thermal evolution process, which can be used to simulate the microstructural evolution and predict the mechanical properties of low carbon steel strip with 0.05–0.25 wt-% C. The developed model has been employed to analyse the effect of the hot rolling process on the microstructure and mechanical properties of the final product. It is shown that slab reheating temperature and time has little influence on the above. Roughing delivery temperature has a small influence on recrystallisation and grain evolution during roughing passes, but no influence on the microstructure and mechanical properties of the final product. Finishing delivery temperature has a larger influence, not only on recrystallisation between finishing passes, but also on subsequent phase transformation after rolling. Coiling temperature has the strongest influence on the microstructure and mechanical properties of the final product, through changing the cooling rate during phase transformation. The present work is helpful for both prediction of mechanical properties and optimisation of the hot strip rolling process.

A significant step forward : the full metallurgical control of the mechanical properties of hot-rolled strip with VAI-Q Strip

VAI-Q Strip is a quality control system, based on physical-metallurgical models, for hot-rolled strip. This joint development of VOEST-ALPINE Industrieanlagenbau and VOEST-ALPINE Stahl Linz allows the automatic on-line control of the mechanical properties using very accurate prediction methods. Since the beginning of 2000, an extended version of the system is in operation at VOEST-ALPINE Stahl Linz and very good quality results, as well as cost savings, have been achieved.

VAIQ Strip - An On-Line System for Controlling the Mechanical Properties of Hot Rolled Strip

VAIQ strip - VAI’s Integrated Quality control for hot rolled - allows, in its present state, accurate on-line prediction of the mechanical properties of hot rolled strip. It supports the control of the mechanical properties via the comprehensive simulation possibilities. The extension of the system to perform a fully automatic in-line control of the quality parameters is just under development. is developed in close cooperation of VOEST-ALPINE Industrieanlagenbau (VAI) and VOEST-ALPINE STAHL LINZ (VASL) and is implemented at the Hot Strip Mill of VASL. The prediction model is in continuous operation since mid of 1997 and has proven to be both accurate and stable.

Cold and hot rolling of iron powder

A BPMF atomized iron powder heated for 20 min at a temperature of 800, 900, 1000, or 1100°C is still characterized by good flowability, readily descends into the region of deformation, and can be rolled into strip. At a temperature above 1100°C this powder sinters into a bar, and can no longer be rolled. The mechanical properties of hot-rolled strips are an order higher than those of cold-rolled ones. Even so, the mechanical properties of strips produced by the hot rolling of the powder under the conditions of the experiments described are inferior to those of P/M parts shaped at room temperature and sintered under optimum conditions. In experiments on the hot rolling of powders between rolls with plain barrels it has proved impossible, because of axial splitting and edge cracking, to obtain nonporous strip of width up to 60 mm. The hot rolling of powders into narrow strips should be performed in closed passes; to reduce the cost of rolls, wide strips should be rolled hot between plain roll barrels, and their edges should then be trimmed.

Continuous Production of Iron Strip from Metal Powder

A continuous method of producing iron strip from powder has been developed. Iron powder directly conversed to green strip by roll compacting, and which was continuously sintered, hot rolled and cooled in hydrogen atmosphere and coiled up. The effects of various continuous powder rolling factors, such as the sintering temperature, roll speed, and hot rolling lood on the properties of hot rolled strip were investigated with Husquvarna Star electrolytic iron powder and Höganäs sponge iron powder.In general, with increasing the sintering temperature and hot rolling lood the physical and mechanical properties of iron strip by powder rolling were improved, whereas the effect of roll speed was different, depending upon the sinterability of iron powder. These properties obtained were considerably well for the powder metallurgical product, although the sintering time was short. According to the repeated hot rolling or annealing and cold rolling, the pro. perties of the iron strip were equal to those of the conventional iron strip, especially the one made from Husquvarna Star iron powder showed superior magnetic properties.