Papers by Keyword: Cold Rolling

Abstract: In order to analyze the effect of entry strip thickness, entry strip crown and intermediate roll shifting on strip profile and rolling force distribution, a three dimension finite element model of rolls-strip in UCM mill was established and employed. The results showed that the increases of entry strip thickness and entry strip crown would lead to the increase of exit strip crown and edge drop under the same total rolling force; the strip crown and edge drop would be decreased if the intermediate roll shifting δi was decreased. Moreover, the rolling force distribution also was analyzed in details by changing the entry strip thickness, the entry strip crown and the intermediate roll shifting.

Abstract: According to the kinematics theory of part surface forming motion and engagement principle, shaping movement of ballscrew manufactured by cold rolling has been investigated. The motion relationship and mathematical model of ballscrew have been built. By means of ADAMS and MATLAB the motion simulation and numerical calculation of cold rolling have been done. From analysis results, motion relationships between roller and workpiece and forming principle of cold rolling have been revealed. These studies will provide quantitative basis for technologic research of cold rolling and promote the study of ballscrew’s cold rolling forming mechanism.

Abstract: Strip shape control during cold rolling of thin strip is a challenge in rolling practice. In the paper, finite element model of strip shape during cold rolling of thin strip in asymmetrical rolling case was successfully developed, and the strip shape such as the thickness distribution along the strip width have been obtained. The developed finite element model has been verified with the experimental value, which shows they are in good agreement. The obtained results are applicable to control the rolled thin strip shape in practice.

Abstract: The microstructure evolution of a two-phase austenitic-ferritic steel after hot rolling and cold rolling (reduction amounts: 20, 40, 60 and 80%) is investigated with the help of the FEG-SEM / EBSD technique. Special phases orientation relationships (Bain, K-S, N-W and G-T) evolution between neighbouring grains of  and  phases have been characterised as a function of the cold rolling reduction. As this later increases fraction of these particular phase orientation relationships decrease. The same evolution is noticed for the 3 grain boundaries inside the  phase. These results are compared to those observed by TEM.

Abstract: The crystallographic texture and grain size have a strong influence on the magnetic properties of FeSi alloys. These microstructural parameters are determined by the thermo-mechanical processing of the material. Here, some recent results on FeSi-alloys with variable Si-content and without phase transformation are presented. Hot rolling conditions were varied in broad interval of parameters and afterwards, the samples were cold rolled and annealed. After the different processing steps, the samples were characterized by optical microscopy, X-ray diffraction and Electron BackScatter Diffraction (EBSD) in order to evaluate the texture, grain size and the homogeneity of the structure through the thickness. This allowed to study the evolution of the intensity of the favourable magnetic texture components during processing.

Abstract: The development of global microstructure characteristics has been compared to the local distribution and extent of Σ3 and Σ3n (1 n 3) grain boundary clusters as a function of thermo-mechanical processing in Type 304 stainless steel. A cold reduction of 5% produced GBE modified microstructures on annealing at 1050°C, containing almost one order of magnitude longer maximum cluster lengths than the corresponding annealing treatments for a reduction of 15%. Differences in the development of the distributions of cluster length scales were observed between the thermo-mechanical treatments. A re-conversion of the longest cluster obtained after GBE processing was observed with long annealing times. The local distribution of Σ3n boundary clusters was assessed, and regions with a low density of clusters are indicative of the onset of GBE conversion of microstructure.

Abstract: High silicon steel with Si content of 6.5wt.% is perspective to be applied in magnetic devices at high frequencies. It is very hard to produce Fe-6.5wt%Si alloy thin sheet by conventional hot-cold rolling method because of its embrittlement at room temperature resulted from the formation of intermetallic phases like B2 and D03. In this paper, embrittlement mechanism, rolling processes, and magnetic properties for the cold rolled Fe-6.5wt.% Si alloy sheets are discussed. Our study indicates that thermal mechanical treatments can improve the ductility of the Fe-6.5wt.%Si alloy. The Fe-6.5wt.%Si alloy sheets of 0.05 mm thickness can be successfully obtained after hot-cold rolling and heat treatments. Lamination pieces can be punched directly from the sheets. Tensile strength as high as 1048MPa and elongation over 3% were measured at room temperature.

Abstract: In the present study, nucleation at Cube bands during annealing of a cold rolled commercial aluminium alloy AA8079 was investigated. The main goal of this work was to provide experimental data for subsequent modelling. By studying the deformed material the geometrical parameters of Cube bands were determined. The Cube band spacing in the deformed state was measured experimentally and accordingly calculated with a simple geometric model, taking the initial Cube fraction in the pre-deformed state and the deformation degree into account. The nucleation frequency during subsequent annealing of the cold deformed material was estimated from the geometry and size of deformed Cube bands prior to deformation. From investigations of the orientation relationship between the Cube oriented nuclei and the adjacent deformed matrix with S orientation, the fraction of 40°<111> grain boundaries having optimum growth conditions, was established.

Abstract: Cold rolling followed by ageing in two grades of superaustenitic stainless steel was performed in order to assess the effect of cold deformation on the precipitation characteristics of these steels. Samples were cold rolled from 20% to 60% reduction in thickness and aged within the temperature range of 650οC to 950οC for times up to 120h. Following ageing precipitation of secondary phases took place, with sigma (σ) phase formation being the predominant precipitate species forming. Secondary phases have been reported to form following isothermal exposure to high temperatures, yet the precipitation behaviour of cold deformed samples has received less attention. When compared to the ageing characteristics of undeformed samples, cold deformation was found to accelerate precipitation during ageing. This study helped clarify a time-temperature-transformation regime relating isothermal ageing of cold deformation that could be applied to these steels in order to avoid occurrence of undesirable microstructural constituents with the associated reduction of mechanical and corrosion properties.

Abstract: Eutectoid steels present a wide range of interesting mechanical properties (high strength, wear resistance, ductility and toughness) and could be a cheaper alternative to high strength low-alloyed steels (HSLA) in applications where weldability is not a critical requirement. The mechanical properties of pearlite are mainly dictated by the interlamellar spacing and the spheroidization of cementite. In this work, the spheroidization kinetics during annealing of a fully pearlitic steel produced in an electric arc furnace (EAF) is investigated. More specifically, the influence of a prior cold deformation and of the interlamellar spacing is studied using image analysis and hardness tests. It is shown that spheroidization is faster in fine pearlite than in coarse pearlite. Prior cold deformation strongly accelerates the spheroidization kinetics in fine and coarse pearlite. The tensile properties corresponding to different pearlite microstructure were measured and are compared to the hardness evolution during annealing.