Papers by Keyword: Wire Drawing

Abstract: An analytical model of the cold wire drawing process is used to implement an optimization procedure. The optimization aims to minimize the number of passes required to achieve a given reduction while maintaining a safe value of the drawing stress in each step. The number of passes and the sequence of intermediate diameters are the output of the optimization model. The sequence of diameters is optimal in the sense that minimizes a mathematical objective function, and their values must be considered a first attempt to determine appropriate values for a specific wire drawing operation. With respect to prior contributions, the work hardening of the material is exploited to reduce the number of passes. The reduction of the number of passes yields lower values of the aspect ratio, defined as the mean diameter divided by the contact length, which is an important factor to prevent the onset of internal defects. The optimization is performed numerically with mathematical programming and metaheuristic algorithms.

Abstract: The present study investigates the tensile behavior of the two bimetallic composite wires Cu-Al and Fe-Al. The purpose is to understand the deviation their tensile strengths show from the Rule of Mixtures’ prediction. To that end, an experimental-numerical approach was adopted. Following tensile testing of the above cold-drawn composite wires, the manufacturing process (wire drawing) was simulated via finite element analysis. The prominent role of processing-induced residual stresses on the yield strength of cold-drawn products is known. Therefore, a discussion based on the axial tensile residual stress profile was developed. It was concluded that the higher-magnitude-near-surface tensile residual stresses in the Fe-Al wire causes its tensile curve to show a negative deviation from the Rule of Mixtures (RoM). The Cu-Al wire, on the contrary, exhibits a slight positive deviation.

Abstract: This study was mainly oriented on the evolution of the crystallographic texture as a function of the deformation resulting from the industrial wire drawing process. This, in fact, will make it possible to establish a relationship between the microstructure and the crystallographic texture in the medium carbon steel wires obtained by industrial wire drawing process and used in the manufacture of spring mattresses in order to minimize the loss of material and to satisfy the users of this product.During this study, a medium-carbon steel wires was characterized by two analytical techniques. The scanning electron microscopy (SEM) to monitor the microstructure evolution and the electron backscatter diffraction (EBSD) for the crystallographic texture analysis. The EBSD results are processed with OIM (Orientation Imaging Microscopy) analysis software.

Abstract: In this paper, the evolution of texture in the ferrite phase and mechanical behavior of cold-drawn pearlitic steel wires produced for strand manufacturing at Trefisoud company was investigated. Wire drawing induces the development of dislocation density, reduction of interlamellar spacing and the refinement of grains size which leads to a strong hardening of the wires. That explains the increase of the tensile strength from 1242 MPa to 2618 MPa with higher deformation. Also, the cementite lamellae are rotated toward the drawing axis and the thickness of lamellae further decreases when strain level increases, this phenomenon leads to a somewhat fibrous structure. The quantitative analysis obtained by EBSD data shows the development of a strong (<110> // ND) texture of the ferrite phase leading to a structural transformation from isotropic to anisotropic.

Abstract: Cold-drawn high-carbon steel wire with pearlite microstructure is one of the most popular raw materials for modern reinforcing ropes. Lamellae thinning, changes in interlamellar interface and metallographic texture, strain localization is the main property-forming phenomena in the wire drawing process. However, the experimental study of these phenomena dynamics is difficult and time-consuming. Drawing process of pearlitic steel wire was investigated. Behavior of pearlite colonies on the surface and the central layer of the wire were researched, based on the multiscale computer simulation. Cementite lamellae orientation in relation to the drawing axis, interlamellar spacing and shape of cementite inclusions were key factors. Regularities of the pearlite colonies reorientation, changing the shape and size of cementite lamellae and strain localization in the ferrite were established on the basis of FEM. It was established that the cementite lamellae, that are parallel to the drawing axis, had the maximum thinning. Interlamellar distance in pearlite colonies with such lamellae changed most intensively. Cementite lamellae, that are perpendicular to the drawing axis, are the most susceptible to fracture. It was found out that for certain values interlamellar distance this effect can be reduced. Intensive reorientation of pearlite colonies in relation to the drawing axis was observed in the case of their location at an angle to the drawing direction. At the same time, there was a significant bending of cementite lamellae and their susceptibility to fragmentation. Estimated values of the wire mechanical properties were compared with a real experiment. The simulation results were verified by metallographic analysis.

Abstract: The study developed a hardness-strain reference curve to be used with the finite element simulation for the prediction of the hardness in the drawn copper wire. The hardness values of the deformed copper specimens from tensile tests were analyzed to construct a relationship between hardness and strain. By using an industrial wire drawing machine, a copper wire was drawn by 5 passes to reduce its diameter from 8 to 4.64 mm. All drawing dies used the same configurations which include an area reduction ratio of 20 percent, an approach angle of 7°, and a bearing length of 0.5 times the feeding wire diameter. The finite element simulations of the wire drawing processes were also performed to predict the effective strains in the drawn copper wires. With the use of the developed hardness-strain curve, the hardness of the drawn wires can be estimated. The results show that the difference between the predicted and measured hardness values is about 10 percent lower in the early stage of the wire drawing process, and the difference increases with the number of passes to about 30 percent higher in the later stage of the process.

Abstract: This study focuses on the evolution in the microstructure, texture and mechanical properties of medium carbon steel wires obtained by wire drawing at Tréfissoud Company for the manufacturing of the spring mattress. Wire drawing induces elongation of grains in the direction of drawing with the development of the <110> fibre texture parallel to the wire axis. Kinking and bending of cementite lamellae were observed during the drawing process. The work was carried out respectively on three states, wire rod and drawn states for two different amounts (ε %=43,6 and 60 %), using the optical and SEM microscopy, electron backscatter diffraction and X-ray diffraction analysis for examination of the microstructure and texture evolution, the hardness Vickers and tensile test to follow the curing of the studied wires.

Abstract: Cu-Pd-Ag alloy is widely used in electronic device applications due to its relatively low electric resistance. To obtain higher strength wire, age-hardening is usually conducted to this alloy wire. However, the detailed hardening mechanism of Cu-Pd-Ag alloy was not clarified enough. In the present paper, we investigated the microstructure and hardness of the Cu-Pd-Ag alloy wire with aging treatment. Original alloy contained many rods with an Ag-rich α phase extended along the wire direction in a Cu-rich α phase matrix. After heat treatment of 623K with 1 hour, the matrix was transformed to the β phase contained many elongated α₂ phases as nanolamellar structure. Many β’ phase precipitated in the rods. Hardness measured with nanoindentation test showed that the matrix had a higher value than that of the rods. In the Cu-Pd-Ag alloy wire, the nanolamellar structure of the matrix was revealed to contribute to the hardening of the wire.

Abstract: This paper is concerned with the effects of process parameters on the shape changes of a micro cementite band in wire drawing of pearlitic steel. Two process parameters, an initial orientation of cementite band and its location, are chosen. In this study, a macro deformation behavior at a material point in macro wire drawing of pearlitic steel is represented by an averaged behavior of a unit model. This unit model is simulated by a micro finite element analysis, while a macro wire drawing of pearlitic steel is simulated by finite element method at a continuum scale. The shape changes of a cementite band would be traced, by solving the unit problem with the changes of boundary conditions corresponding to the macro deformation behaviors of material points along a particle path. The predicted shapes of cementite bands are compared to those by the experiments reported in the literature. Qualitative comparisons between the current predictions and experiments verify the proposed method. Effects of an initial orientation of cementite band and its location on its shpae changes are presented. It was also noted that the most micro deformation in a unit model occurs in the deformation zone.

Abstract: The article pesents the drawing process of the circular cross-section rod. The mechanical model of plastic deformation in the process of wire drawing is represented by the regularities of yielding of metal at the level of forward flow during the rolling based on theoretical solutions proposed by A. I. Tselikov. The method for determination of drawing forces was probed about by decomposing it into two problems of planar deformation and the superposition of these solutions. The results of the theoretical solution of wire drawing task were used to determine the coefficient of friction during the deformation of low carbon steel in diameter 5.5 mm by means of comparison with the known experimental results of the wire drawing efforts. Satisfactory results were obtained for evaluation of frictional forces during deformation under high plastic deformation zone conditions. The obtained values of friction coefficients can be used to solve the wire drawing tasks and under conditions of a high hearth of plastic deformation as well.