Papers by Keyword: Hot Rolling

Abstract: The hot rolled single sided stainless steel clad plate of 316L stainless steel and Q345C steel was carried out in a hot rolling line by the technology of “electron beam vacuum welding and hot rolling”. High quality single sided stainless steel clad plates were produced by asymmetrical compound billet and asymmetrically rolling. The productions of stainless steel clad plate have reached the requirements of GB / T 8165-2008. The interface shear strength is greater than 320 MPa. The yield strength is greater than370 MPa. The tensile strength is greater than 520 MPa. The elongation is greater than 30%, A good metallurgical bonding between stainless steel and carbon steel was achieved. The bonding rate reached 100%. The composite interface is straight and perfect. The pilot production in the study has laid down the certain basis for the production of the single-side dissimilar-material composite board.

Abstract: System analysis is used as the effective way for design and modification of different kinds of technical systems. Application of system analysis to any technological process allows to present the links between input and output parameters which makes it possible to analyze its effectiveness and effect on the process for manufacturing of the object with necessary level of quality. The paper presents results of system analysis application for multioperational technological processes. The main aim of hot rolling process is manufacturing the hot rolled metal sheet with definite geometrical parameters which are necessary for further cold rolling process. The scheme of hot rolling operation with its input and output links is presented. The obtained results can be used for mathematical modeling of hot rolling operation. It is shown the application of system analysis for technological process of coating on the example of vacuum ion-plasma coating process. Because of existence of operated, noncontrolled, and indignant parameters of the coating process application of system analysis is the effective way for structural analysis of this technical system. It is proposed to supplement system analysis with function-oriented analysis. This approach can state the links between properties of the object which are sufficient for its application and technological parameters of the manufacturing technological process.

Abstract: During the hot rolling of bainitic steels, time and temperature must be controlled within narrow limits to avoid undesirable ferritic or martensitic phase fractions. In order to design a reliable process window for the production of bainitic steels, the effects of the different process parameters on the phase transformation and the final properties of a microalloyed and a non-microalloyed steel were investigated. Thermomechanical tests with the possibility of producing secondary samples were conducted to analyze the influence on the mechanical properties strength and toughness. Transmission electron microscopy (TEM) and electron probe micro analysis (EPMA) were used to investigate the origin of the differing properties. In particular, it has been found that thermomechanical rolling of the microalloyed steel leads to an improvement in strength. This is partly due to the transformation kinetics and partly to strain-induced precipitations. Further, the hardening behavior is affected by the secondary phase within the bainitic matrix configured through the cooling strategy. Coarse Martensite/Austenite (MA) structures reduce toughness, whereas finely dispersed MA islands increase the hardening potential. Furthermore, the results from the material experiments were used to develop a rate model in combination with a nucleation model to predict the kinetics of the phase transformation and the shape of the bainitic microstructure.

Abstract: No recrystallization of austenite, Tnr, has an important influence on the transformed phase fractions and the final crystallographic texture after hot deformation. This paper investigates the evolution of microstructure and texture components during hot-rolling in two austenitic region based on Tnr along with three different cooling trajectory and coiling in dual-phase steels and high strength low alloys steel. The recrystallization of the austenite, the austenite deformation followed by the austenite-to-ferrite transformation influence the final microstructure and texture in dual phase steels, have been examined by means of optical microscopy, X-ray diffraction (XRD) measurements. Recrystallized and deformed austenite have clearly different texture components and, due to the specific lattice correspondence relations between the parent austenite phase and its transformation products, the resulting ferrite textures are different as well.

Abstract: Results of researches of process of hot rolling of ingots from the experimental aluminum alloy which is economically alloyed by scandium are given. The computer model of process of hot rolling with the use of which the straining, temperature and speed processing modes conditions is calculated and also power parameters of processing is calculated in applied to industrial conditions. It is shown that the use in the model of a certain shape of the ingot faces (Petrov's lock) and indirect rolling action in the edging stand is made it possible to reduce the likelihood of the formation and further development of micro cracks on the edges of rolled metal. The adequacy of results of modeling was confirmed by carrying out pilot-industrial tests when rolling large-size ingots from the experimental alloy and obtaining batches of hot-rolled plates and sheets of various sizes. The tensile test was used to study deformed samples after rolling and samples obtained on five regimes of heat treatment with varying heating temperatures of 300, 350 and 380 oС and holding time in the furnace for 1 and 3 hours. The results of the studies on samples of hot-rolled sheets 10 mm thick showed that, compared with the initial state, the strength characteristics of the metal after heat treatment are reduced by an average of 12-20%, and plastic characteristics increase by 50-65%. In this case, the heat treatment regimes 1 - 3 give a good ratio of the ductility and plastic properties of the metal.

Abstract: Due to their advantageous strength-weight ratio, good recyclability, excellent noise and vibration damping properties as well as excellent dent resistance, magnesium materials offer a variety of uses in modern lightweight structures. As a result, a comeback of magnesium alloys is to be seen in multiple industrial applications, especially in the automotive industry, as the potential for lightweight, cost-effective lightweight industrial construction associated with the lightest metallic engineering material helps to meet even stricter energy and environmental efficiency guidelines. Traditionally, casting processes have been the dominant magnesium manufacturing processes, but in the last decade, an increasing number of lightweight structural applications have been implemented with magnesium wrought alloys. In this paper, the current state of developments focusing the twin-roll casting (TRC) of semi-finished products of magnesium alloys will be presented. By reducing the number of process steps in combination with a unique microstructure, the near-net-shape TRC process offers new options to provide magnesium materials meeting current and future requirements for semi-finished products, constructions and moldings in terms of type, quantity and quality.

Abstract: The mechanical properties of Fe-28%Mn-1.5%Al and Fe-0.6%C-18%Mn-1.5%Al-0.07%Nb (all in wt.%) steels subjected to hot plate rolling at a temperature of 1423 K with a total reduction of 60% were studied. The steels exhibited quite different mechanical properties in spite of almost the same original microstructures and similar stacking fault energies. The yield strength and total elongation of the Fe-28%Mn-1.5%Al steel are about 260 MPa and 45%, respectively, whereas those properties in the Fe-0.6%C-18%Mn-1.5%Al-0.07%Nb steel comprise 350 MPa and 53%, respectively. The tensile flow stress vs strain curves of the hot rolled steel samples can be described by Ludwigson-type relations with parameters being dependent on the strengthening mechanisms. Frequent deformation twinning in the Fe-0.6%C-18%Mn-1.5%Al-0.07%Nb steel promoted the strain hardening and improved the strength and ductility.

Abstract: The simulation of industrial rolling processes has been shown to be an important method to optimize rolling parameters, reduce production costs and improve product quality. Previous works have shown the value of hot rolling simulation by means of torsion tests where the mean-flow-stress (MFS) can be successfully predicted. In the present work, three rolling schedules are simulated by hot torsion tests and compared. It is important to note this methodology provides the flexibility to test different ideas without the risk of downtime or damage to plant equipment that could result from an unsuccessful industrial trial. The simulation analysis considered the production steps from reheating through the final accelerated cooling as well as the final product microstructures. The study provides important information to the production of various steel grades such as pipeline, shipbuilding, structural and other high-end products.

Abstract: A robust model for calculating the necessary process variables such as strain, strain rate and temperature in hot rolling of a steel plate or strip is presented in this paper. The applied approach includes a well-constructed velocity function in the deformation model that is validated using a commercial finite element solver. The developed microstructure model is then integrated into the process model and includes the most essential descriptions of restoration and austenite grain structure evolution phenomena during hot rolling. Furthermore, the concept of hierarchical grain structure evolution is described as a method track the evolution of un-recrystallized and recrystallized features of the microstructure throughout a given pass schedule. The most important outcome of this approach is that each grain size component is modelled separately based on its prior thermomechanical history. A computer implementation of these models called MICDEL is used together with a simulation example to demonstrate its capability of predicting process variables and austenite grain structure evolution in hot strip rolling of steel.

Abstract: The microstructure of Al-1.01Mg-1.11Si-0.38Cu-0.69Mn aluminum alloy plate hot-rolled from homogenization and homogenization-free ingots were investigated by optical microscopy and scanning electron microscopy assisted with energy dispersive spectroscopy (SEM/EDS). The results showed that there are 3 main kinds of constituents such as Mg₂Si, AlCuMgSi and AlFeMnSi in the as-cast Al-1.01Mg-1.11Si-0.38Cu-0.69Mn aluminum alloy ingot. After homogenization treated at 545°C for 24h, the black Mg₂Si and the white bright AlCuMgSi particles in the ingot dissolved into matrix, but the grey AlFeMnSi phase partly dissolved, contracted into sphere and become coarse, many ultrafine dispersoids appear in the dendritic arms. The constituents in the plates hot-rolled from the homogenization and homogenization-free ingots are both distributed as broken chains along the rolling direction. However, compared with the particles configuration in the plate that hot-rolled from homogenization ingot, the particles in the plate that hot-rolled from the homogenization-free ingot are finer, more numerous and more homogenous, and with insufficient recrystallization when the plates are solution treated at 545°C for 2 h and then water quenched.