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This study presents a comprehensive numerical analysis of the wire drawing process, with a particular focus on the impact of pass sequencing on the central burst defect in AA-6005 aluminum alloy wire. The finite element method is used to study the effects of incremental reduction rates across various stages of the drawing process. Specifically, the analysis involves achieving a 95% total reduction rate distributed among three distinct configuration ranges: decreasing, constant, and increasing reduction rates. Key parameters such as principal stresses, damage distribution, residual hydrostatic pressure, and plastic power are examined to predict adjustments in drawing force, axial surface stress, and die stress for enhancing process quality. The cuppy wire and stress concentrations causing central burst (chevron) formation and fractures were predicted during the simulation. For this, different die diameters were used in the analysis. This analysis was performed on the Forge® NxT 3 finite element code and validated with the wire drawing test results of the literature. Notably, the study identifies the third configuration range as particularly effective in mitigating central bursting, emphasizing a significant finding. [ABSTRACT FROM AUTHOR]

It is well known that residual stresses and accumulated deformations during drawing processes can influence mechanical properties of the resulting products. This paper proposes the use of machine learning methods, such as artificial neural networks (ANN) and polynomial regression, to gain insight into the nature of these distributions across the cross-section of round wires. The necessary data sets were generated using finite element simulations (FEM), and several calculations were performed to select the optimal model configuration for these methods. To select the best quality metric, metrics such as mean absolute percentage error (MAPE), mean square percentage error (MSPE), and R-squared ( R 2 ) were evaluated. A statistical analysis was also conducted using Friedman's and Nemenyi's tests to compare the two methods. It was found that both ANNs and polynomial regression can be used to predict residual stress and strain distributions. However, it is more preferable to use ANNs for the former and polynomial regression for the latter because; in this case, the smallest error in the obtained predictions is achieved. [ABSTRACT FROM AUTHOR]

Obtaining the desired strip profile is of paramount importance in cold rolling. The final strip profile depends on several parameters of the plants including crown and taper profiles and segmented backup roll positions. This paper aims to present a newly developed combined finite element-analytical model of the rolling mill able to model not only the roll cluster but also the mill housing and backup bearings deformations. This makes the proposed model especially suitable to simulate cluster-type rolling mills. The model exploits a modified elastic foundation formulation for a precise computation of the contact forces between rolls, taking into account rolls' crown and taper. A reduced stiffness matrix approach is implemented for accurate mill housing modeling. A full 3D finite element model of the rolling mill and experimental data are used for the validation of the presented model. By exploiting the validated model, the paper shows that the deformation of supporting bearings and mill housing plays a crucial role in the strip profile calculation and should be included in any cluster-type roll mill model. [ABSTRACT FROM AUTHOR]

In this study, a numerical analysis was conducted on the ductile fracture of a 2-mm diameter Mg-1Zn-0.5Mn-0.5Sr-0.1Ca alloy wire during drawing. The hexagonally close-packed crystal structure of Mg alloys causes asymmetric fracture behavior, especially in the compression region. The aim of this study is to develop a comprehensive damage model for Mg alloy wire that accurately predicts ductile fracture, with a focus on the compression region. A novel experimental method was introduced to measure the ductile fracture of Mg alloy wires under different stress states. The wire drawing process was simulated using the Generalized Incremental Stress-State dependent damage (GISSMO) Model and the Semi-Analytical Model for Polymers (SAMP) model. The damage model's prediction and the experimental results were found to be in excellent agreement, especially in determining crack initiation. Computational analysis established a safe zone diagram for die angle and reduction ratio, and experimental validation confirmed the feasibility of this approach. The proposed damage model can provide a practical and reliable analysis for optimizing the drawing process of Mg alloy wire.

The effect of cold drawing on the evolution of microstructure and texture of near eutectoid steel wire is studied to understand the deformation micromechanism of the wire drawing process. The texture evolution during wire drawing is simulated using a viscoplastic self-consistent (VPSC) model and successfully validated by experimental results. The favorable pearlitic colonies having lamellas aligned along the wire axis are found to undergo thinning and form a fibrous structure. On the other hand, the lamellas oriented perpendicularly to the wire axis are found to undergo bending and kinking in the process of aligning themselves with the wire axis. A ⟨ 011 ⟩ crystallographic texture develops after the wire drawing from the ⟨ 111 ⟩ and ⟨ 110 ⟩ texture of the as-received steel. The VPSC simulation illustrates the relative significance of the {112} ⟨ 111 ⟩ slip in comparison to that of the traditionally used {110} ⟨ 111 ⟩ slip. The VPSC simulation also illustrates presence of about 5 – 6 active slip systems (AVACS) that make it possible to maintain strain compatibility in polycrystalline materials. [ABSTRACT FROM AUTHOR]

• This study develops a comprehensive damage model for Mg alloy wire in drawing process. • The research focuses the analysis of asymmetric fracture properties in compression and tensile region. • Novel approach was devised to identify the damage model for predicting fractures. • This analysis provides a process window of a Mg alloy wire regarding temperature and strain rate. In this study, a numerical analysis was conducted on the ductile fracture of a 2-mm diameter Mg-1Zn-0.5Mn-0.5Sr-0.1Ca alloy wire during drawing. The hexagonally close-packed crystal structure of Mg alloys causes asymmetric fracture behavior, especially in the compression region. The aim of this study is to develop a comprehensive damage model for Mg alloy wire that accurately predicts ductile fracture, with a focus on the compression region. A novel experimental method was introduced to measure the ductile fracture of Mg alloy wires under different stress states. The wire drawing process was simulated using the Generalized Incremental Stress-State dependent damage (GISSMO) Model and the Semi-Analytical Model for Polymers (SAMP) model. The damage model's prediction and the experimental results were found to be in excellent agreement, especially in determining crack initiation. Computational analysis established a safe zone diagram for die angle and reduction ratio, and experimental validation confirmed the feasibility of this approach. The proposed damage model can provide a practical and reliable analysis for optimizing the drawing process of Mg alloy wire. [Display omitted] [ABSTRACT FROM AUTHOR]

This document summarizes a study on the recovery of waste powder soap used in the wire drawing process. The study found that a physical separation method using ion solution was able to recover 98% of the sodium-based waste powder soap. The recovered material was analyzed using thermal and chemical analyses, which showed that the sodium content in the recycled soap was similar to that of the original soap. The study concluded that this recovery method was efficient and could be applied to different types of wires. The article emphasizes the importance of recycling processes for disposing of production-related waste in an environmentally friendly manner. [Extracted from the article]

Near-surface axial tensile residual stresses (from manufacturing) are reportedly detrimental to the yield strength of cold-drawn wires. Therefore, a reliable evaluation of their magnitude is necessary. The size and geometry of electrical wires can pose challenges for experimental measurement of those residual stresses. For that reason, the finite element analysis can prove useful. However, great care must be taken with the right choice of strain hardening law for a sound assessment of residual stresses. Given the complex loading condition during cold drawing, cyclic loading arises through the wire cross section even in single-pass drawing. As a result, it is of crucial importance to account for associated backstresses. The current study makes a comparison between two different hardening laws' prediction of axial residual stress profiles in numerically cold-drawn Cu–Al composite wires of various Al volume fractions. The impact of die geometry on this prediction was also examined for a 25%Al-wire. To that end, a combined isotropic-kinematic law and a pure isotropic constitutive equation were considered. The results imply a possible overestimation of residual stresses by the pure isotropic model at relatively low Al volume fractions. The difference between the maximum magnitudes of tensile or compressive residual stresses (predicted by the two models) could be as large as about 100 MPa (larger than the yield strength of the starting materials). Furthermore, the tooling geometry minimally affects the prediction of the hardening models. In conclusion, backstresses are not to be overlooked for accurate estimations of drawing residual stresses at low Al volume fractions. [ABSTRACT FROM AUTHOR]

As a result of conventional wire-forming processes, the residual stress distribution in wires is frequently unfavorable for subsequent forming processes such as bending operations. High tensile residual stresses typically occur in the near-surface region of the wires and can limit further application and processability of the semi-finished products. This paper presents an approach for tailoring the residual stress distribution by modifying the forming process, especially with regard to the die geometry and the influence of the drawing velocity as well as the wire temperature. The aim is to mitigate the near-surface tensile residual stresses induced by the drawing process. Preliminary studies have shown that modifications in the forming zone of the dies have a significant impact on the plastic strain and deformation direction, and the approach can be applied to effectively reduce the process-induced near-surface residual stress distributions without affecting the diameter of the product geometry. In this first approach, the process variant using three different drawing die geometries was established for the metastable austenitic stainless steel X5CrNi18-10 (1.4301) using slow (20 mm/s) and fast (2000 mm/s) drawing velocities. The residual stress depth distributions were determined by means of incremental hole drilling. Complementary X-ray stress analysis was carried out to analyze the phase-specific residual stresses since strain-induced martensitic transformations occurred close to the surface as a consequence of the shear deformation and the frictional loading. This paper describes the setup of the drawing tools as well as the results of the experimental tests. [ABSTRACT FROM AUTHOR]

High-strength, high-conductivity copper/silver-alloyed materials were prepared by cold-spray (CS) manufacturing. For DC high-field application at room temperature, bulk Cu/Ag (5% vol. Ag) alloys with high mechanical properties and high electrical conductivity can be obtained by CS and post-heat treatments. For pulsed-field application at liquid nitrogen temperature, bulk Cu/Ag (5% vol. Ag) alloys serve as precursors for room-temperature wire drawing. The Cu/Ag-alloyed bulk CS deposit presents a high yield strength of about 510 MPa with a corresponding electrical resistivity of 1.92 µΩ·cm (at 293 K). The Cu/Ag-alloyed wires show a very high ultimate tensile strength (1660 MPa at 77 K or 1370 MPa at 293 K) and low electrical resistivity (1.05 µΩ·cm at 77 K or 2.56 µΩ·cm at 293 K). Microstructural studies via STEM allow us to understand this very high level of mechanical strength. The results evidence that materials developed by CS exhibit very high mechanical properties compared to materials prepared by other routes, due to the high velocity of the deposited particles, which leads to high initial deformation rates and specific microstructural features. [ABSTRACT FROM AUTHOR]

Wires of a Cu--3.8 wt% Zr alloy were produced by conform extrusion followed by wire drawing up to 0.2mm in diameter (S wire), or by conform extrusion and subsequent annealing during wire drawing up to 0.2mm (IA wire). The effects of microstructure on the strength and electrical conductivity of the S and IA wires were investigated. The severely drawn S and IA wires had a mixed microstructure consisting of a Cu parent phase with fine grains, fibrous eutectics elongated along the drawing direction, and granular eutectics. The 0.2% proof stress (·0.2) and tensile strength (·u) of the S and IA wires increased monotonically with increasing drawing ratio (©). The S wire with © = 7.8 exhibited large values of ·0.2 = 1080MPa and ·u = 1320 MPa. The S and IA wires having the mixed microstructure are strengthened primarily by high density of dislocations and grain refinement in the Cu phase and by the presence of fibrous and granular eutectics. The electrical conductivity (E) of the S wire increased in the early stage of wire drawing and then began to decrease, dropping to 42% IACS at © = 7.8. The increase in E is caused by refining of the eutectics, which was formed during casting, toward the granular or fibrous form. The E value of the IA wire after annealing was high, 72%IACS, and then decreased as © increased. Values of E of the S and IA wires with the mixed microstructure was estimated by applying rules of mixtures. The estimated values of E are in agreement with the measured values of E. It is shown that the presence of the fibrous and granular eutectics significantly increases the electrical conductivity. [ABSTRACT FROM AUTHOR]

The paper focuses on the investigation of AISI 302 steel wire of different initial diameters, in solutionized condition. Three different drawing schedules were realized, starting from three different diameters, where two smaller-gauge wires were obtained by drawing of large-diameter wire and applying solution heat treatment to the product. However, the drawing schedules were carried out with almost the same total reduction and similar partial reductions. The measurement of drawing force was performed for each drawing pass, and the samples of wire were taken after each pass. The samples were then tested to obtain a set of mechanical and technological properties, as well as the distribution of Vickers hardness on wire cross section. Finally, the effect of different history of deformation and heat treatment on drawing process stability and final properties of drawn wires was discussed.

This investigation aims to analyze the effect of homogenization heat treatment at 1240 °C for 2 and 6 h on the hardness, distribution, morphology, and chemical composition of the δ-ferrite and sigma phases in 316L stainless steel cast billet. A field emission scanning electron microscope, combined with electron back-scattered diffraction, a field emission electron probe microanalyzer with a wavelength dispersive spectrometer, and a Vickers microhardness tester are applied to identify various phase evolutions in the cast billet. The morphology of the δ-ferrite and sigma phases in the austenite matrix of the 316L cast billet are strongly related to the subsequent hot and cold wire drawings. The homogenization heat treatment is expected to provide a driving force to form spheroid interdendritic δ-ferrite and to minimize the amount of the brittle sigma intermetallic compound in the austenite matrix. The homogenization heat treatment at 1240 °C effectively spheroidized all δ-ferrites into blunt ones in the cast billet. The transformation of δ-ferrite into sigma is dominated by temperature and cooling rate. The fast air cooling after homogenization between 1240 and 850 °C retards the precipitation of the sigma in the δ-ferrite. There are two δ-ferrite transformation mechanisms in this experiment. The direct transformation of the δ-ferrite into sigma is observed in the as-cast 316L stainless steel billet. In contrast, the eutectoid transformation of the δ-ferrite into the sigma and austenite dominates the 316L cast billet homogenized at 1240 °C, with a slow furnace cooling rate. [ABSTRACT FROM AUTHOR]

The wire drawing process is an essential technique in mechanical and industrial operations in lots of applications. Therefore, the current article aims to employ different methodologies (i.e., experimental, numerical) to investigate the optimum operating conditions and lubrication type on the surface and mechanical quality of these wires. By examining the effects of die angle, drawing speed, and lubricant type on wire drawing outcomes, the research not only provides valuable insights into process optimization but also contributes to reducing defects and enhancing wire properties. Results demonstrate significant variations in tensile strength based on these parameters, highlighting the need for precise control over process variables to achieve desired outcomes consistently. Moreover, statistical analyses reveal substantial relationships between process variables and tensile strength, offering a deeper understanding of the underlying mechanisms driving wire drawing performance. Overall, this research not only advances the understanding of wire drawing processes but also offers practical insights for improving wire manufacturing techniques, ultimately bolstering product quality, reducing costs, and increasing competitiveness in the global market. [ABSTRACT FROM AUTHOR]

• Chinese 'silk and metal carpets' from imperial workshops examined for the first time. • Characterisation of the mechanical production of the metal threads. • Ancient examples of brass coated metal threads. • Comparison with the Asian production of metal carpets outside of China. Chinese 'silk and metal carpets,' mainly made by imperial workshops during the Qing Dynasty (1644–1911), are very luxurious and until now have not scientifically and technically been investigated. From the point of view of materials, a typical feature is the presence of metal threads which embellish backgrounds or details with a precious and golden appearance. Metal threads from a wide number of Chinese carpets were non-destructively investigated by XRF, while an in-depth characterization by SEM-EDS was performed on samples from few carpets. Although copper is always the main constituent of very thin metallic strips wound around a core of silk, the obtained results showed three types of strips, different in terms of materials and/or methods of making. The most frequent typology, covering over 85% of the investigated carpets, derives from the drawing of brass-plated copper wires. The obtained results are read and interpreted according to geographical and historical context, pertaining to the metallurgy and the making of metal threads, extending the comparisons also to other contexts in eastern and western world, during the ages. [ABSTRACT FROM AUTHOR]

The paper focuses on the investigation of AISI 302 steel wire of different initial diameters, in solutionized condition. Three different drawing schedules were realized, starting from three different diameters, where two smaller-gauge wires were obtained by drawing of large-diameter wire and applying solution heat treatment to the product. However, the drawing schedules were carried out with almost the same total reduction and similar partial reductions. The measurement of drawing force was performed for each drawing pass, and the samples of wire were taken after each pass. The samples were then tested to obtain a set of mechanical and technological properties, as well as the distribution of Vickers hardness on wire cross section. Finally, the effect of different history of deformation and heat treatment on drawing process stability and final properties of drawn wires was discussed. [ABSTRACT FROM AUTHOR]

As a result of conventional wire-forming processes, the residual stress distribution in wires is frequently unfavorable for subsequent forming processes such as bending operations. High tensile residual stresses typically occur in the near-surface region of the wires and can limit further application and processability of the semi-finished products. This paper presents an approach for tailoring the residual stress distribution by modifying the forming process, especially with regard to the die geometry and the influence of the drawing velocity as well as the wire temperature. The aim is to mitigate the near-surface tensile residual stresses induced by the drawing process. Preliminary studies have shown that modifications in the forming zone of the dies have a significant impact on the plastic strain and deformation direction, and the approach can be applied to effectively reduce the process-induced near-surface residual stress distributions without affecting the diameter of the product geometry. In this first approach, the process variant using three different drawing die geometries was established for the metastable austenitic stainless steel X5CrNi18-10 (1.4301) using slow (20 mm/s) and fast (2000 mm/s) drawing velocities. The residual stress depth distributions were determined by means of incremental hole drilling. Complementary X-ray stress analysis was carried out to analyze the phase-specific residual stresses since strain-induced martensitic transformations occurred close to the surface as a consequence of the shear deformation and the frictional loading. This paper describes the setup of the drawing tools as well as the results of the experimental tests.

High-strength, high-conductivity copper/silver-alloyed materials were prepared by cold-spray (CS) manufacturing. For DC high-field application at room temperature, bulk Cu/Ag (5% vol. Ag) alloys with high mechanical properties and high electrical conductivity can be obtained by CS and post-heat treatments. For pulsed-field application at liquid nitrogen temperature, bulk Cu/Ag (5% vol. Ag) alloys serve as precursors for room-temperature wire drawing. The Cu/Ag-alloyed bulk CS deposit presents a high yield strength of about 510 MPa with a corresponding electrical resistivity of 1.92 µΩ·cm (at 293 K). The Cu/Ag-alloyed wires show a very high ultimate tensile strength (1660 MPa at 77 K or 1370 MPa at 293 K) and low electrical resistivity (1.05 µΩ·cm at 77 K or 2.56 µΩ·cm at 293 K). Microstructural studies via STEM allow us to understand this very high level of mechanical strength. The results evidence that materials developed by CS exhibit very high mechanical properties compared to materials prepared by other routes, due to the high velocity of the deposited particles, which leads to high initial deformation rates and specific microstructural features.

Temperature rise of a specimen is a significant issue in drawing industries for wire, rod, and bar products, because an excessive increase in temperature during the drawing process can deteriorate the product quality and die life. The influence of the strain hardening exponent (n) of a wire on the temperature and strain distributions during wire drawing is investigated to understand its effect and to improve the quality of drawn wire. Finite element analysis and experiments are conducted to analyze the temperature and strain distributions of wires with n values of 0.0, 0.1, 0.5, and 1.0. The temperature increase of the wire augments as the n of the wire increases, despite the same amount of ideal plastic deformation, which is associated closely with the redundant work. The shear strain increases with the n of the specimen, which generates redundant work, leading to a high temperature rise. Similarly, drawing force increases with the n of the specimen, owing to the increase in redundant work with the n of the wire. In addition, the drawing force presents a linear relationship with the temperature rise of the wire. The drawing speed should be reduced and/or the cooling of wire and die should be strengthened during wire drawing, with increasing n value of the wire, because product quality and die wear are highly associated with the temperature rise of the wire in the deformation zone. [ABSTRACT FROM AUTHOR]

Radial forging of metallic materials requires both high temperatures and large plastic deformation. During this process, non-metallic inclusions (NMIs) can debond from the metallic matrix and break apart, resulting in a linear array of smaller inclusions, known as stringers. The evolution of NMIs into stringers can result in matrix load shedding, localized plasticity, and stress concentrations near the matrix-NMI interface. Due to these factors, stringers can be detrimental to the fatigue life of the final forged component, especially when present near a free surface. By performing a finite element model of the forging process with cohesive zones to simulate material debonding, we contribute to the understanding of processing-induced deformation and damage sequences on the onset of stringer formation for both Type 1 and Type 2 alumina NMIs in a Ni-200 matrix. Through a parametric study, the interactions of forging temperature, strain rate, strain per pass, and interfacial decohesion on the NMI damage evolution metrics are studied, specifically NMI particle separation, rotation, and cavity formation. For Type 2 alumina NMIs, embedded in a Ni-200 matrix, the simulations indicate that at temperatures below 800 °C, particle separation dominates the NMI damage sequences, whereas at temperatures between 900 °C and 1000 °C, below an interfacial bond strength of 178 MPa, cavity formation is the dominate damage evolution mechanism, resulting in matrix load shedding and stress concentrations around the NMI. [ABSTRACT FROM AUTHOR]

The deformation behavior of nearly fully pearlitic, bainitic and martensitic steels during severe plastic deformation is summarized in this paper. Despite their significantly different yield stresses and their microstructures, their hardening behavior during SPD is similar. Due to the enormous hardening capacity the SPD deformation is limited by the strength of the tool materials. The microstructure at the obtainable limit of strain are quite similar, which is a nanocrystalline structure in the order of 10 nm, dependent on the obtainable strain. The nanograins are partially supersaturated with carbon and the grain boundaries are stabilized by carbon. Another characteristic feature is the anisotropy in grain shape which results in an anisotropy of strength, ductility and fracture toughness. The results are important for the development of ultra-strong materials and essential for this type of steels which are frequently used for application where the behavior under rolling contact and sliding contact is important. [ABSTRACT FROM AUTHOR]

Most of wire drawing processes is performed at room temperature, causing rising up the heat due to the plastic deformation and the generated friction at the work piece-tool interface. In the poor lubrication conditions, there is a likelihood that both the die and the drawn wire will be damaged. This is because the drawing load is greatly influenced by tool geometry and lubrication conditions, The research work conducted in this paper focuses on drawing of 3 mm diameter Electrolytic tough pitch (ETP) cooper wire to perform 20% reduction in cross sectional area through a conical die. Various parameters have been tested to study the effect of them on the forming load during wire drawing including die angle (4°,6°,8°), bearing distance (1.2, 1.5, 1.8) mm, and lubricant types (Lithium-based greases, soap powder, oil HP). The first phase of this paper is conducted to estimate the coefficient of friction for each lubricant type, Utilizing the experimental values of drawing force in theoretical formals. Based on the estimated values obtained, the second phase was creating numerical model to extend the work to more parameters level as well as check the results validation. The results demonstrated that the drawing force increases with increasing of bearing distance and friction coefficient.

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This paper describes research on the influence the technology of zinc-coated steel wire manufacturing has on the energy and force parameters of the drawing process, energy consumption and zinc expenditure. In the theoretical part of the paper, the theoretical work and drawing power were calculated. Calculations of the electric energy consumption have shown that usage of the optimal wire drawing technology results in a 37% drop in energy consumption, which in the course of a single year translates to savings equal to 13 TJ. This, in turn, results in the decrease of CO2 emissions by tons and a total decrease of the eco-costs by approximately EUR 0.5 mln. Drawing technology also influences the losses of the zinc coating and CO2 emissions. Properly adjusted parameters of the wire drawing technology allow obtaining a zinc-coating that is 100% thicker, translating to 265 tons of zinc, whose production generates 900 tons of CO2 and incurs eco-costs equal to EUR 0.6 mln. Optimal parameters for drawing, from the perspective of decreased CO2 emissions during the zinc-coated steel wire manufacturing, are as follows: usage of the hydrodynamic drawing dies, angle of the die reducing zone α = 5°, and drawing speed of 15 m/s. [ABSTRACT FROM AUTHOR]

In this paper, the effects of the skin pass technique on the residual stress and plastic strain fields generated in cold drawn pearlitic steel wires are analyzed. The aim is to find out the optimal conditions to be used in the design of a manufacturing process for obtaining more reliable structural components in terms of the main cause of failure: the hydrogen embrittlement (HE). To achieve this goal, diverse numerical simulations were performed by using finite elements (FE) and considering, on one hand, the first step of a real cold drawing chain, using (i) a conventional drawing die and (ii) modified drawing dies with different soft diameter reductions, and, on the other hand, numerical simulations by FE of the hydrogen diffusion assisted by stress and strain states to estimate the hydrogen distributions. Obtained results revealed the secondary reduction degree as a key parameter in the die design for reducing the drawing-induced residual stress. According to the results, low values of the reduction ratio cause radial distributions of residual stress with significant reductions at both the wire core and at the wire surface. In addition, the hydrogen accumulation at the prospective damage zone (near the wire surface) given by FE simulations is lower in the wires drawn with modified drawing dies including a skin pass zone. [ABSTRACT FROM AUTHOR]

The effects of contact conditions at the wire–die interface on the temperature distribution of the specimen and die are investigated to understand the wire drawing process. Finite element analysis and experiments are performed to analyze the temperature distribution of a drawn wire and die based on different contact conditions using a low-carbon steel wire. The maximum temperature (Tmax) of the die decreases as the contact heat transfer coefficient at the wire–die interface increases, whereas that of the wire increases with the contact heat transfer coefficient. The Tmax of the die and wire decreases with the thermal conductivity of the die. As the thermal conductivity of the die increases, the heat generated by friction is rapidly absorbed into the die, and the Tmax of the die decreases, thus resulting in a decrease in the surface temperature of the wire. The Tmax of both the die and wire linearly increases with the friction factor. In particular, the Tmax of the die more sensitively changes with the friction factor compared with that of the wire. The Tmax of the die linearly increases with the drawing velocity, whereas that of the wire parabolically increases with the drawing velocity. The influence of bearing length on the temperature increase in both the wire and die is insignificant. [ABSTRACT FROM AUTHOR]

This investigation aims to analyze the effect of homogenization heat treatment at 1240 °C for 2 and 6 h on the hardness, distribution, morphology, and chemical composition of the δ-ferrite and sigma phases in 316L stainless steel cast billet. A field emission scanning electron microscope, combined with electron back-scattered diffraction, a field emission electron probe microanalyzer with a wavelength dispersive spectrometer, and a Vickers microhardness tester are applied to identify various phase evolutions in the cast billet. The morphology of the δ-ferrite and sigma phases in the austenite matrix of the 316L cast billet are strongly related to the subsequent hot and cold wire drawings. The homogenization heat treatment is expected to provide a driving force to form spheroid interdendritic δ-ferrite and to minimize the amount of the brittle sigma intermetallic compound in the austenite matrix. The homogenization heat treatment at 1240 °C effectively spheroidized all δ-ferrites into blunt ones in the cast billet. The transformation of δ-ferrite into sigma is dominated by temperature and cooling rate. The fast air cooling after homogenization between 1240 and 850 °C retards the precipitation of the sigma in the δ-ferrite. There are two δ-ferrite transformation mechanisms in this experiment. The direct transformation of the δ-ferrite into sigma is observed in the as-cast 316L stainless steel billet. In contrast, the eutectoid transformation of the δ-ferrite into the sigma and austenite dominates the 316L cast billet homogenized at 1240 °C, with a slow furnace cooling rate.

It is investigated to what extent the evolution of ductile damage in cold forging can be controlled without changing the geometry of the produced part. Besides the effects of strain hardening and residual stresses, damage, which is the nucleation, growth and coalescence of voids on microscopic level, affects product properties of the manufactured components such as fatigue strength, impact strength, or elastic stiffness. Former investigations have shown that the load path-dependent damage evolution in forward rod extrusion, and thus, the performance of produced parts can be controlled by the process parameters extrusion strain and shoulder opening angle. As these parameters also affect the geometry of extruded parts, design requirements of components might be violated by varying these. Thus, counterpressure is used to superpose purely hydrostatic stresses to forward rod extrusion in order to decrease triaxiality in the forming zone without causing geometric variations in the produced parts. The counterpressure is either introduced by a counterpunch or by modified process routes. The achieved improvements in product performance are in agreement with results obtained by variation of extrusion strain and shoulder opening angle as described in the literature. In addition, it is observed in tensile tests that damage in cold extruded parts does not significantly affect flow stress. All advancements in product performance are realized without affecting the products' geometries. [ABSTRACT FROM AUTHOR]

Round-notched samples are commonly used for testing the susceptibility to hydrogen embrittlement (HE) of metallic materials. Hydrogen diffusion is influenced by the stress and strain states generated during testing. This state causes hydrogen-assisted micro-damage leading to failure that is due to HE. In this study, it is assumed that hydrogen diffusion can be controlled by modifying such residual stress and strain fields. Thus, the selection of the notch geometry to be used in the experiments becomes a key task. In this paper, different HE behaviors are analyzed in terms of the stress and strain fields obtained under diverse loading conditions (un-preloaded and preloaded causing residual stress and strains) in different notch geometries (shallow notches and deep notches). To achieve this goal, two uncoupled finite element (FE) simulations were carried out: (i) a simulation by FE of the loading sequences applied in the notched geometries for revealing the stress and strain states and (ii) a simulation of hydrogen diffusion assisted by stress and strain, for estimating the hydrogen distributions. According to results, hydrogen accumulation in shallow notches is heavily localized close to the wire surface, whereas for deep notches, hydrogen is more uniformly distributed. The residual stress and plastic strains generated by the applied preload localize maximum hydrogen concentration at deeper points than un-preloaded cases. As results, four different scenarios are established for estimating "a la carte" the HE susceptibility of pearlitic steels just combining two notch depths and the residual stress and strain caused by a preload. [ABSTRACT FROM AUTHOR]

The effect of the thermal properties of steels on wire drawing behavior has been investigated to understand and improve the wire drawing process. Finite element analysis and experimental tests were conducted to analyze the temperature distribution of the deformed specimens with different thermal properties. The thermal properties of twinning-induced plasticity (TWIP) steel were measured and compared with those of plain carbon steel. Based on the measurement of thermal properties, wire drawing behaviors were systematically compared with thermal conductivity of the specimen (k) using plain low-carbon steel with high k and TWIP steel with low k. The results revealed that the k of TWIP steel was approximately one third of that of low-carbon steel, and the thermal expansion coefficient of the TWIP steel was approximately 50% higher than that of low-carbon steel in the temperature range of 26–400 °C. The temperature distributions in the wire strongly depended on the k of the wire during wire drawing. TWIP steel exhibited higher maximum temperature, and took a longer time to attain the equilibrium temperature than low-carbon steel during wire drawing owing to the low k. The maximum temperature of the die increased with decreasing k of the wire, indicating that die wear can increase with decreasing k of the wire. Therefore, reducing the drawing speed is suggested for a wire with low k, such as high-alloyed metals, especially for TWIP steels. [ABSTRACT FROM AUTHOR]

Most of wire drawing processes is performed at room temperature, causing rising up the heat due to the plastic deformation and the generated friction at the work piece-tool interface. In the poor lubrication conditions, there is a likelihood that both the die and the drawn wire will be damaged. This is because the drawing load is greatly influenced by tool geometry and lubrication conditions, The research work conducted in this paper focuses on drawing of 3 mm diameter Electrolytic tough pitch (ETP) cooper wire to perform 20% reduction in cross sectional area through a conical die. Various parameters have been tested to study the effect of them on the forming load during wire drawing including die angle (4°,6°,8°), bearing distance (1.2, 1.5, 1.8) mm, and lubricant types (Lithium-based greases, soap powder, oil HP). The first phase of this paper is conducted to estimate the coefficient of friction for each lubricant type, Utilizing the experimental values of drawing force in theoretical formals. Based on the estimated values obtained, the second phase was creating numerical model to extend the work to more parameters level as well as check the results validation. The results demonstrated that the drawing force increases with increasing of bearing distance and friction coefficient. [ABSTRACT FROM AUTHOR]

In this article, a mathematical model of the wire's average temperature change in the process of multiple drawing on high-speed straight-line drawing machines has been developed. The calculation results showed that the average temperature of the wire during a drawing at a speed of up to 45 m/s on straight-line drawing machines could reach 400 °C. Deformation heating of the wire during drawing does not exceed 60 °C, and heating due to sliding friction can reach 300 °C, depending on the friction coefficient, which ranges from 0.05 to 0.15. The average strain rates under the conditions of the modern high-speed drawing process reach 7000 s−1. Over the course of the research, it was found that there are no conditions for the occurrence of dynamic deformation aging due to impurity atoms of carbon, nitrogen and oxygen. At the same time, at the temperature and speed parameters of the high-speed wire drawing, conditions are created for the onset of the dynamic strain aging of steel in the presence of hydrogen atoms. Therefore, during heat treatment and pickling, it is necessary to exclude the hydrogenation of steel. It has been established that in order to exclude static strain aging of steel during drawing, it is necessary to prevent heating the wire above 180–200 °C. [ABSTRACT FROM AUTHOR]

Welding wires are widely used as electrodes in various welding processes. To produce welding wires, wire rods are drawn gradually to final diameters at welding wire manufacturers. During the wire drawing process, premature failure happens frequently due to various reasons, and a type of wire drawing failure originated from wire surface V-shaped cracks or so-called chevron-like cracks is often found. In this research, V-shaped cracks on drawn welding wire surfaces of ER70S-6 steel were characterised carefully and its underlying mechanism was discussed thoroughly. It was found that the V-shaped cracks on wire surfaces are often present in pairs with opposite directions. Martensite microstructure was found nearby the V-shaped cracks, and its formation can be attributed to deteriorated local lubrication during wire drawing, which causes the austenitization of the wire surface and the subsequent formation of martensite. The large friction on wire surface induces the development of V-shaped cracks along the drawing direction. Meanwhile, as martensite is difficult to deform, strain localization happens in the ferrite/pearlite matrix, and V-shaped strain localization areas were found around the martensite, leading to the development of V-shaped cracks in the opposite direction of the drawing direction. [ABSTRACT FROM AUTHOR]

Temperature rise of a specimen is a significant issue in drawing industries for wire, rod, and bar products, because an excessive increase in temperature during the drawing process can deteriorate the product quality and die life. The influence of the strain hardening exponent (n) of a wire on the temperature and strain distributions during wire drawing is investigated to understand its effect and to improve the quality of drawn wire. Finite element analysis and experiments are conducted to analyze the temperature and strain distributions of wires with n values of 0.0, 0.1, 0.5, and 1.0. The temperature increase of the wire augments as the n of the wire increases, despite the same amount of ideal plastic deformation, which is associated closely with the redundant work. The shear strain increases with the n of the specimen, which generates redundant work, leading to a high temperature rise. Similarly, drawing force increases with the n of the specimen, owing to the increase in redundant work with the n of the wire. In addition, the drawing force presents a linear relationship with the temperature rise of the wire. The drawing speed should be reduced and/or the cooling of wire and die should be strengthened during wire drawing, with increasing n value of the wire, because product quality and die wear are highly associated with the temperature rise of the wire in the deformation zone.

The present paper considers the wire drawing process through a conical die and provides an approximate solution for the drawing force, assuming an arbitrary hardening law. The solution is based on the upper bound theorem. However, this theorem does not apply to the stationary flow of strain-hardening materials. Therefore, an adopted engineering approach is to replace the original material model with a non-homogeneous, perfectly plastic model. The kinematically admissible velocity field is derived from an exact semi-analytical solution for the flow through an infinite channel, which increases the accuracy of the solution. The solution for the homogeneous perfectly plastic material compares with an available solution. The general solution is valid for any die angle. The numerical example focuses on the range of angles used in wire drawing. Since the material model is pressure-independent, it is straightforward to adopt the solution for calculating the force in extrusion. [ABSTRACT FROM AUTHOR]

This paper presents an experimental and numerical analysis of damage evolution in AA2011 aluminum alloy wires drawn under different scenarios. To this end, load-unload tensile tests were firstly carried out in order to characterize the degradation of the mechanical response in every cycle where the experimental results show a bilinear damage relationship in terms of the effective plastic strain. Therefore, a modification of the classical Lemaitre model is proposed in this work in order to reproduce bilinear paths of damage with the addition of only two parameters that can be directly obtained from the material characterization. Then, the damage predictive capability of this new experimental-based model is assessed in numerical simulations of the drawing process in one and two passes (considering for this last case the sequential and tandem configurations) where the computed predictions are compared with the corresponding experimental data showing a good agreement between them. [ABSTRACT FROM AUTHOR]

The present study is concerned with the mechanical properties of Cu-Al wires manufactured via cold drawing. The common approach for improving the tensile strength of drawn wires is to optimize the operational parameters. Those parameters include the die geometry, amount of area reduction at each pass, drawing speed, lubrication and so on. Optimization helps homogenize the plastic deformation during wire drawing. That in turn minimizes the undesirable effect of processing-induced tensile residual stresses forming near the wire surface. The current investigation introduces a novel optimization approach to modify the residual stress distribution with a focus on the fiber-matrix configuration rather than the operational parameters. To that end, residual stress distributions in the two configurations I- conventional copper-clad aluminum and II- so-called “Architectured” wires were compared at the same Cu/Al volume fraction. The comparison was performed using the finite element analysis. Experimental stress–strain curves, numerical residual stress profiles, and equivalent plastic strain contours were then plotted for both conventional and novel configurations. The findings suggest that the novel composite wires offer remarkably better tensile behavior along with other already-known electrical and thermal advantages. This could be ascribed to their architectural features such a continuous copper network and fine Al fibers. Therefore, the new fiber-matrix configuration could remove the need for optimization of various operational parameters or post-drawing treatments for a given wiredrawing set-up. [ABSTRACT FROM AUTHOR]

The present review paper would celebrate the 25 years anniversary of the ESAFORM association by summarizing the studies performed by the delegates of the ESAFORM conference series within mini-symposium “Extrusion and Drawing” and of the papers published in the International Journal of Material Forming in the same fields. The 160 analyzed papers have been divided in four main categories corresponding to the paper main chapters (Hot Metal Extrusion, Cold Metal Extrusion, Polymer Extrusion and Drawing) then further divided in sub-chapters in order to group them in more specific research subjects. The aim of this review paper is then to provide to the reader a complete overview of the investigated topics and of the research trends over the years within the ESAFORM associate researchers. [ABSTRACT FROM AUTHOR]