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International audience; 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.

In industrial applications, copper wire is often used in the cable core or the motor armature. These copper wires are made by passing copper rods through the round-hole mold in a wire drawing machine. To reduce friction, it is necessary to use a lubricant mixed with oil and water for lubrication. The oil would be consumed over time, so it is required to add oil in a while to maintain lubrication. Generally, concentration sensors are used to monitor the concentration of lubricant to determine the timing of replenishing the oil. The principle of the sensor is by the intensity change of optical reflection to detect the concentration. However, copper chips scraped off from the wire during the drawing process will gradually accumulate on the surface of the sensor, thus causing sensor misdetection due to the shading of the light source. In this paper, an improved concentration sensing system is proposed to solve this problem. In the proposed system, a clean water tank is placed beside the oil tank, and the sensor is located in the clean water tank most of the time and is moved to the oil tank for measurement only at a specific time. After the measurement is completed, it will return to the clean water tank. This can greatly reduce the time the sensor is immersed in the oil tank, minimizing the chance that the sensor is shielded by copper scraps. To enable the sensor to move in this manner, a novel linkage design is proposed to meet several requirements in the movement of the mechanism. The mechanism is featured by its simple structure and only one driving device is needed. Furthermore, motion analyses of the mechanism are provided. Finally, we explain the working principle of the measurement system where the proposed linkage and the concentration sensing system are combined. To sum up the results, the proposed method can effectively expand the frequency of on-site maintenance from monthly to annual, which greatly reduces manpower requirements and effectively improves stability.

Due to its electro-mechanical properties, commercially pure aluminium wires have attracted the interest of automotive industry representing a functional and efficient economic solution to reduce vehicle’s weight leading to the diminishing of energy consumption and emissions in today’s society. However, to consolidate its use in this sector and in new market realities, it is necessary to increase the flexibility of the aluminium conductor wires, consenting their installation in very small spaces and with high curvatures, avoiding any failure and electrical conductivity decrease. Thus, the evolution of microstructure and service performance need to be investigated and controlled to improve the service safety. The present research shows a new approach to efficiently continuously manufacture long wires with smaller diameters and fine grains at room temperature. It is studied the strengthening effects (yield and tensile strength, plasticity, hardness), the electrical conductivity and the microstructural changes of commercial 1370 pure aluminium (99.7% Al) when traditional wire drawing process is combined with equal channel angular drawing (ECAD) technique. The results of this proposed procedure of deformation “drawing-ECAD-drawing” show an evident benefit, compared to the classic technology of production of aluminium wire, obtaining fine grain structure product with superior mechanical strength and not influenced electrical conductivity. The proposed manufacturing approach leads to fine wires enhancing the material mechanical properties by microstructural evolution (i.e. grain size reduction) avoiding the traditional post manufacturing thermal treatments requiring a high amount of energy and time and careful steps.

Numerical modeling was conducted to investigate the deformation behavior of powder mixture during multi-pass drawing processes for multi-filamentary MgB2 wire. A modified Drucker-Prager Cap (DPC) model with an elliptical cap surface using the new material characterization method was developed to capture the anisotropic hardening behavior and hydrostatic effect of the powder mixture. A number of uniaxial die compaction, cold isostatic pressing, diametrical compression, and uniaxial compression tests were conducted using different powder densities to characterize the modified DPC model. A commercial finite element software ABAQUS with a user subroutine was used to simulate the drawing of the MgB2 wire. The density and area fraction of the powder mixture during the wire-drawing process were verified with experimental results. The difference in packing density at the inner and outer filaments of the MgB2 wire was successfully captured by simulation. In addition, the effect of the initial packing density on the superconducting properties of MgB2 wire was numerically studied. It is shown that the increase in the superconducting area, which results from a high initial packing density, should be more effective compared to the increase in the grain connectivity in enhancing the critical current properties for the MgB2 wire when the final packing density is saturated after a number of drawing processes.

The present work discusses the evolution of microstructure and non-metallic inclusions during wire drawing process in a synthetic slag-treated 5.5 mm diameter high carbon wire rod steel. It has been observed that failure of the as-received wire rod (without synthetic slag treatment) takes place at different stages of deformation during wire drawing operation. However, in case of the synthetic slag-treated wire rods (TW specimen), failure takes place consistently at ~ 95% reduction in the cross-sectional area of the wire. In a quest to understand the failure mechanisms during wire drawing process, a systematic study has been carried out by analyzing the microstructures and non-metallic inclusions in the steel wires drawn at various stages of deformation. The improved drawability of the treated wire specimens is attributed to the decrease in the amount of unfavourable non-deformable inclusions in the steel matrix, and this stems from the synthetic slag treatment of the liquid steel. Microstructural investigation also confirms the complete realignment of pearlite colonies along the wire drawing direction followed by thinning and disintegration of cementite lamellae at higher deformation, particularly in case of the synthetic slag-treated wire rod steel.

Rhodium is a rare material with excellent mechanical and electrical properties. Rhodium is used in various industries, and fine rhodium wire in particular is used in electronic components. The aim of this study was to fabricate a 30.0 µm fine rhodium wire from an 80.0 µm initial wire using a multi-pass wire drawing process. A drawing pass schedule was designed to fabricate the 30.0 µm rhodium wire. An elastic-plastic finite element analysis was performed to validate the designed multi-pass wire drawing process. A wire drawing experiment was performed to fabricate the 30.0 µm fine rhodium, and the qualities of the final wire were evaluated. The final diameter of the wire was 29.85 µm.

Despite the sufficient exploration of industrial methods for the manufacturing of products from metal hafnium, the public domain has a limited number of reports that highlight the technological aspects of hafnium wire manufacturing and their effect on the structure and mechanical properties of the products formed [1, 2]. This article describes the methods employed in the manufacturing of hafnium wire from the ingots of its own production, which have been tested by Chepetsk Mechanical Plant (CMP) under industrial conditions, as well as the advantages and disadvantages of each tested method for producing the wire. The stages of hafnium wire drawing are described in detail. During the experiments, the relationships between the technological, energy–power parameters, surface quality, and material structure were studied. The effects of the type of drawing tool on the wire surface quality and drawing force were revealed, as well as the effects of the wire diameter on the amount of permissible deformation between the annealed products and the grain size of the metal. The paper reports the results of studies conducted on the structure, mechanical, and corrosion properties of the experimental samples of wires manufactured in compliance with the ASTM B737 standard specification for hot rolled and/or cold-drawn hafnium rods and wire. Currently, CMP can manufacture wires with a diameter of 1 mm or more from hafnium ingots of its own production, in compliance with the ASTM B737 standard.

In this paper, the effect of wire drawing on the microstructures, mechanical properties, and shape memory effect of compositions Cu87.85-Al11.70-Be0.45 (CAB) and Cu87.73-Al11.70-Be0.45-Zr0.12 (CABZ) has been experimentally investigated. The wires with a diameter of 1.33 mm are manufactured from the casted round bars through the rolling and drawing (secondary) process. Investigations are performed on microstructure and phase for both as-cast and wire-drawn SMAs. Further, wire-drawn SMAs are investigated for phase transformation temperatures, hardness, ductility, and shape memory effect. The results show that the average grain size decreased with 73.06% by adding Zr to the CAB alloy. Further, the grain size of CABZ alloy wire decreased with 67.38% in the longitudinal direction and 67.07% in the transverse direction as compared to CAB alloy wire after the secondary process. Improvement of the grain structure in CABZ alloy wire resulted in an enhancement in the hardness of 13.86% in longitudinal and 12.43% in the transverse direction, and tensile strength of 134.58% and ductility of 177.06%. The phase transformation temperatures reduced by the addition of Zr, and better shape recovery is observed in CABZ alloy wire.

Spring steel is a name given to a wide range of steels used in the manufacture of springs, prominently in automotive and industrial suspension applications. High carbon of HC82BCr grade steel is drawn in the range of 4.0–3.0 mm as per customer’s requirement for production of spring mainly in automobile components. This spring steel grade is produced from continuous cast billet of size 150 mm × 150 mm and then hot rolled into the size of 5.5 mm diameter wire rod. Quality aspects of these spring are significant as any inherent abnormality in the material could lead to unwanted productivity losses or quality claims or sometimes serious safety issues. In this present study, spring samples broken during coiling stage were collected from plants for understanding their quality aspect and potential causes of breakage during production. Detailed microstructural investigation revealed that the root cause of breakage of the spring is related to the segregation of phosphorous and chromium in the billet which leads to the formation of martensite (brittle and less ductile) in wire rod during rolling process. This volume change due to formation of martensite increases the stress level at the interface of pearlite and martensite. During wire drawing, this increased stress level causes formation of internal crack in subsequent passes causing breakage during spring formation.

An experimental and finite element study of the effect of the multiplicity of wire drawing regime stages and wire drawing speed on microhardness distribution in steel wire cross section is conducted. Microhardness dependencies are obtained at the surface and within the center of wire on diameter for steel wire multistage drawing. The effect of drawing rate on wire microhardness using a Beloretsk Metallurgical Plant Koch KGT 25/12 drawing machine is studied. A finite element modeling method is used to study the effect of overall reduction, drawing rate, and number of drawing regime stages on deformation distribution in a wire cross section, as well as the distribution of strain rate in the deformation zone cross section. It is established that microhardness in the steel wire central area starts to increase relative to the microhardness at the surface when a total reduction of about 0.7 is achieved. Strain within the central region of the wire increases with respect to that at the surface with an increase in overall reduction and a reduction in the number of drawing regime stages.

A systematic method is proposed for optimizing the die geometry and processing conditions of a multi-pass wire-drawing process. In the proposed approach, FEM simulations based on the robust Taguchi design method are first performed to determine the drawing force, maximum surface axial stress, and maximum die stress for given values of the reduction angle, bearing length, and back tension properties of the die. The Taguchi analysis results are then used to train a neural network (NN) to predict the wire-drawing outcome for any given values of the input parameters. Finally, a genetic algorithm (GA) based on the NN is employed to determine the optimal settings of the input parameters. The validity of the GA optimization results is confirmed by means of FEM simulations. A simple method is proposed for visualizing the optimization results in 3-D space. The feasibility of the proposed framework is demonstrated by means of a practical case study involving a five-pass wire-drawing process for AISI 1022 low carbon steel.

This study has focused on the use of chromium metal as a chemical barrier in the production of in situ MgB2 wires. The chromium metal was plated homogeneously into the initial iron tube by electroplating in order to produce in situ mono-core and multi-filamentary Fe/Cr/MgB2 wires. Cr metal has maintained its continuity through the wire drawing, but inhomogeneous thickness of Cr-coating at the Cr/Fe interface region without chemical reaction to each other is revealed. The in situ mono-core Fe/Cr/MgB2 wire with a diameter of 1.32 mm and multi-filamentary wires with 1.00 mm and 1.26 mm diameters were produced by PIT process and heat treated at different annealing temperatures and times. Transport and structural investigations of the wires indicated locally positive effect of Cr-coating on Fe2B phase formation, transport properties, and the core structure of MgB2 wires. The mono-core Fe/Cr/MgB2 wire-coded A24 has the highest engineering critical current density of 56 A/cm2 at 30 K under 6.5 T.

The relationship between the process condition of wire-drawing and the microstructural evolution during the subsequent annealing was investigated for the production of high-purity copper wires. Three wire-drawing process conditions were considered according to the reduction in the area per pass and the die angle, and their effects on the evolution of the grain structure and texture during annealing were investigated. Strain distributions, calculated using the finite element method, showed that the shear strain near the wire surface varies according to the process condition. The electron backscatter diffraction results indicate that the location on the cross-section of the wire, where secondary recrystallization initiates during annealing, is closely related to the shear strain during wire-drawing. Meanwhile, the effect of shear deformation on the grain structure and texture after primary recrystallization is insignificant. Drawing process conditions with a small reduction in the area per pass and die angle resulted in a relatively small shear strain and gave rise to the onset of secondary recrystallization at the central region of the wires. In contrast, the condition with a large reduction in the area per pass and die angle led to a high shear strain and the onset of secondary recrystallization at the peripheral region of the wire. The observed primary and secondary recrystallization behavior during annealing was explained from the viewpoint of dynamic material phenomena and inhomogeneity in the local recrystallization texture, regulated by the extent of shear deformation during wire-drawing.

Microstructural evolution and mechanical behavior of commercially pure Fe during severe deformation by cold caliber rolling followed by wire drawing were investigated using transmission electron microscopy and electron backscatter diffraction. Following by a drastic increment of strength in the early stage of deformation, shear banding as a softening mechanism leads to decreasing of work hardening rate and finally a steady state situation at medium strains, creating a bimodal microstructure. Increasing strain beyond 3 is associated with increasing the rate of work hardening and refinement of the material. Severely deformed Fe after cold caliber rolling to equivalent strain of 4.5 evolves from lamellar ultrafine-grained structure. Additional deformation by drawing results in more homogeneous structure and activates new mechanisms. A dynamic recovery appears at severe strains through mechanically assisted triple junction motion. It is found that suppression of triple junction motion enhances the refinement of microstructure and the strength, such that the highly deformed Fe after equivalent strain of 7 has a nano/ultrafine-grained structure combined with a high tensile strength of 1115 MPa.

In order to study the transformation-induced plasticity (TRIP) effect in a NiTi shape-memory alloy composite, an in situ NbTi-NiTi composite was prepared by vacuum arc melting, hot forging and wire drawing. An unusual ductile–brittle variation phenomenon was observed by means of a series of tensile tests. The composite was brittle in the absence of transformation at 200 °C, and the fracture strain was about 2%. With lowering the tensile temperature, the composite became ductile when stress-induced martensitic transformation occurred, and the elongation increased to about 18% (a ninefold increase) during tensile test at room temperature. This ductile–brittle variation phenomenon indicates that the stress-induced martensitic transformation of NiTi alloy helps to improve the ductility of the composite, which is just the exhibition of TRIP effect in the NbTi-NiTi composite. Different from conventional TRIP steels, the TRIP behavior in NiTi induces only an increase in the elongation, but not any increase in fracture strength.

The thermomechanical processability of Ti(Hf)-rich Ni49.8Ti30.2Hf20 (at.%) high-temperature shape memory alloy (HTSMA) wires was examined. Hot-extruded rods with an initial diameter of 6.35 mm were hot-rolled and cold-drawn into a final diameter of 260 µm. For all samples, processing was performed in open air without extrusion canning. The HTSMA rods were processed to an area reduction of 99.83%. Experimental results showed that hot-rolling at 800 °C decreased the grain size and introduced a small amount of retained austenite, while breaking up the Ti4Ni2Ox intermetallic oxide phase, resulting in a 10 °C decrease of the austenite start temperature (As). While both hot-rolling and cold-drawing exhibited clear effects on the thermomechanical properties, neither the number of hot-rolling passes nor the number of cold-drawing passes affected the transformation temperatures of the material. Additionally, the NiTiHf HTSMA showed similar thermomechanical responses after the 5th and 25th hot pass when subjected to room temperature loading to 500 MPa (uniaxial tension) and thermally induced shape recovery.

The paper is devoted to the study of the mechanical, microstructural, and bio-corrosive behavior of low-alloyed Zn–Mg biodegradable surgical wires for bone reconstructions. Three biodegradable alloys with different magnesium content have been studied, their production technology has been developed and the product properties have been determined. The technology includes casting, extrusion, hot and cold drawing of the wire, and the product surface finishing. The paper shows the most important stages of the process (i.e., extrusion and drawing) in detail. The technological parameters have been selected based on the results of the computer modeling. The flow stress–strain curves of extruded materials have been obtained at various strain rates and temperatures. Two drawing technologies have been compared. The first one is the room temperature conventional wire drawing. In the second one, the first few passes have been made at an elevated temperature and the rest at room temperature. This allowed avoiding the breaking of the wire during the first passes (a typical issue of the conventional technology for these alloys) and increasing the ductility of the final product. Mechanical properties, bio-corrosion, and crystallographic texture of the material were determined at different stages of the processing. A simultaneous increase in the wire strength, the number of repeated bending until the rupture of the wire, and in the bio-corrosion rate due to drawing has been registered. This phenomenon coincided with a change in the crystallographic texture. It has been shown that the product tensile strength of about 250–300 MPa can be reduced by about 30% due to surgical knots tied on it.

The effect of drawing speed on temperature rise and microstructure distribution in twinning-induced plasticity (TWIP) steel during wire drawing has been investigated to improve drawability for wire rod applications. Although wire drawing process is performed at room temperature, heat is generated due to the plastic deformation and friction at the wire–die interface. The steel wires subjected to the low drawing speed (LD) of 0.5 m/min and the high drawing speed (HD) of 5.0 m/min were analyzed using the numerical simulation and electron backscatter diffraction techniques. Interestingly, the specimens subjected to the HD had a higher drawability by about 18% compared to the LD, which is totally different from the general behavior of plain carbon pearlitic steels. The LD wire had uniform temperature distribution along the radial direction during wire drawing. In contrast, the HD wire had a temperature gradient along the radial direction due to the higher frictional effect at surface: the minimum temperature of 58 °C at center area and the maximum temperature of 143 °C at surface area. The higher stacking fault energy of HD wire at the surface area due to the high temperature rise retarded twinning rate, resulting in the prevention of fast exhaustion in ductility in comparison with the LD wires since the earlier depletion of twins at surface area is known as the main reason for the fracture of TWIP steel during wire drawing. Consequently, HD process delayed the fracture strain of wire and increased the uniformity of microstructure and mechanical properties along the radial direction.

The effect of drawing direction on microstructure and mechanical properties in twinning-induced plasticity (TWIP) steel during wire drawing has been investigated to improve drawability for wire rod applications. The steel wires subjected to unidirectional (UD) and reverse-directional (RD) wire drawing were analyzed. The yield and tensile strength processed by the RD were slightly higher than those by the UD, whereas the ductility and drawability have inverse features, which is totally different from the results of plain carbon steel and Al wire. Although final shear strain of wires deformed by the RD is lower than that by the UD, the RD wires had a more complex stress history and a higher texture component at the surface area, which encouraged twinning rate, resulting in fast exhaustion of ductility, finally earlier fracture of wires. In contrast to the materials deformed by mainly slip mechanism, the RD process cannot improve the ductility and drawability in TWIP steel due to the stress state dependency of twinning mechanism. Also, based on the different strengthening behaviors between pearlitic and TWIP steels during UD and RD, it is induced that microstructure and applied stress state simultaneously control the mechanical properties.

The effects of reduction in area (RA) per pass during caliber rolling on microstructure and strain distribution of twinning-induced plasticity steel have been investigated to find solutions to make a more homogeneous material along the radial direction for wire rod applications. The steel wires subjected to an average RA per pass of 2.5% (skin pass caliber rolling) and 10.0% (conventional caliber rolling) were analyzed. The skin pass caliber-rolled wire was characterized as a duplex fiber texture of major and minor , and the textures were almost same at/between center and surface area, which is totally different from those of conventional caliber rolling and wire drawing. The skin pass caliber rolling led to more homogeneous microstructure and mechanical properties along the radial direction in comparison with the conventional caliber rolling and wire drawing due to the more homogeneous Hall–Petch hardening, dislocation hardening, and texture behavior with area, resulting in higher formability.

The effects of microstructure and deformation mode on the formability have been investigated to understand and improve formability in twinning-induced plasticity (TWIP) steel. The tensile and wire drawing behaviors were compared using the ferritic, pearlitic, and TWIP steels. The drawability of ferritic and pearlitic steels was quite good in spite of the low tensile elongation of hot-rolled state, whereas TWIP steel showed a low drawability despite the extraordinary tensile elongation. In TWIP steel, the gradual increase in twin volume fraction with increasing strain with the aid of grain rotation increased the ductility by delaying the growth of a local necking to fracture, which is the main reason why TWIP steel had a higher elongation during tensile test. The local saturation of deformation twins due to the inhomogeneous plastic deformation during forming process led to the earlier fracture in TWIP steel. For example, the earlier saturation of deformation twin at surface area led to earlier fracture of drawn wire, resulting in low drawability. This proposed fracture mechanism well explained the lower formability and higher strain hardening rate in TWIP steels under the complex stress states such as wire drawing, cup forming, caliber rolling, hole expansion, and dome stretch. To improve the formability in TWIP steels, twinning rate needs to be delicately controlled with area during plastic deformation, especially complex forming process. Four strategies were proposed to improve the formability of TWIP steels, which can help in producing high strength products using TWIP steels.

This study investigates the effect of strain rate (SR) on the strain rate sensitivity (SRS), strain rate work hardening (SRWH) in Co–35Ni–20Cr–10Mo alloy (MP35N) wires, subjected to drawing practices namely full die drawing (FDD) and half die drawing (HDD). The experimental results illustrate that the strength, and SRWH, of the drawn wires, increased with the rise of SR, whereas the SRS(m) and the ductility decreased with the increase of strain rate (10⁻⁶ s⁻¹ to 10⁻² s⁻¹). However, the relative strength, hardening, and the m values were observed to be higher in the FDD drawn wire when compared to the HDD drawn wire. The increase in strength and hardening rate of the FDD drawn wire with the rise in SR was ascribed to increased dislocation density and reduced twin thickness, and the increased SRS and ductility at low SR were attributed to the increased grain boundary (GB) activities. The HDD drawn wire had a relatively lower strength, SRWH and SRS rate at an SR of 10⁻⁶ s⁻¹ when compared to other SR, this was attributed to plastic flow localization, which led to the formation of shear bands in the material. An abnormal SRWH was observed in the HDD drawn wire tested to an SR of 10⁻² s⁻¹, where a Stage II hardening peak was observed at a very high strain, this was attributed to the solute segregation of the Mo atoms to the GB. Economic Development Board (EDB) This work was supported financially by EDB (Economic Development Board) Singapore (COY-15-IPP-140010/198501914Z) under the EDB-IPP scheme through a grant to Heraeus Materials Singapore Pte Ltd Singapore.

Wire rod is an intermediate product, used in the manufacture of cold head quality steel. The quality of the wire rod in the as-hot-rolled condition, was evaluated in a series of carbon steels with and without boron content and at two different wire rod thicknesses. While the effect of boron on hardenability in the hardened and tempered condition is well studied, the effect of boron on the quality in the ferrite–pearlite condition is not well analysed. Hence the present study established that the addition of boron improved strength and ductility in carbon steels compared to steels without boron. The increased strength was attributed to the increased pearlite content and fineness of interlamellar spacing, and the strength was compared with Gladman’s equation and a theoretical equation. The room-temperature flow curve evaluation showed a higher strain hardening exponent in boron-containing steel compared to the steel without it. The upset ratio, which measured the ability of the wire rod for the subsequent wire drawing operation, was found to decrease with carbon content for steels without boron, while it was found to marginally increase in boron-containing steels. The evaluations were substantiated with microstructures evaluated in different grades and thicknesses.

Wire drawing is a cold work metal forming process which is dependant of a functional lubrication process. If the lubrication fails, there is a risk that both the tools and the produced wire will be damaged. Process monitoring of wire drawing is rare in today’s industry since there are no commercialised methods that deliver consistent results. In this paper, a method for monitoring of the wire drawing process is proposed and evaluated. A thermal imaging camera was used for acquiring thermal images of the wire as it leaves the drawing tool. It was found that the proposed method could capture changes in the wire drawing process and had correlation to the drawing force. An equation for estimating the friction condition between the wire and the drawing die using the wire temperature was also proposed and evaluated against experiments. The results showed that the new equation produced results that correlated well to results obtained using a conventional equation that use drawing force.

This study investigates the influence of cold wire drawing practices namely full die drawing (FDD) and half die drawing (HDD) on the deformation homogeneity in Co-35Ni-20Cr-10Mo alloy (MP35N) wires which are used for manufacturing implantable medical products. The inhomogeneous factor was used to assess the level of inhomogeneity in the wires, and electrical conductivity was measured on the wires, after drawn to different cold work (CW) reductions and with different drawing practices. Electron beam scattered diffraction, field emission scanning electron microscope and transmission electron microscope characterization were performed on the wire samples to correlate the mechanical and electrical properties to their texture and grain size. The results of this study conclude that the wires drawn with the FDD practice exhibited homogenous deformation, uniform microstructural and hardness gradient across the wire when compared to HDD wires. The electrical conductivity of the HDD-drawn wires was higher than the FDD wires and the level of inhomogeneity and the variation of conductivity decreased with the increase in CW. EDB (Economic Devt. Board, S’pore)

This study addresses some aspects regarding a computer modelling based on three-dimensional Frontal Cellular Automata (FCA) for the simulation of ultrafine-grained (UFG) microstructure development in purpose-designed microalloyed austenite model alloy i.e. FCC structure. Proposed in the present study model is a step forward towards understanding the deformation and microstructure development mechanisms occurring during severe plastic deformation (SPD) processes with high accumulation of the plastic deformation effects in FCC structures. The analysed microalloyed austenite microstructures were developed due to SPD effects. Using the proposed computer model, based on three-dimensional FCA it has been shown that it is possible to predict some characteristics of the FCC microstructures such as the grain size and the distribution of the boundaries misorientation angle. These abilities were proved by the qualitative and quantitative comparisons of the modelling and SEM/EBSD results. The capabilities of the proposed model were tested using experimental results of the wire drawing processes. The paper presents the new original results of experimental studies of multi-staged MaxStrain technology with the microscopic investigation. Basing on data obtained from these studies, the dependencies of the evolution of grain structure and misorientation angle on the accumulative strain and cycle number were obtained in a form of approximation equations. The equations were implemented into the CA model, and MaxStrain technology was simulated. Comparison of the results obtained in experimental studies and simulations shows a satisfactory agreement. Industrial verification of the developed model as well shows a satisfactory agreement.

Ni-Mo low alloy steel exhibits an admirable amalgamation of high strength and toughness at subzero temperature and show resistance to brittle fracture with good weldability. This steel has been established to fulfill the needs of specific applications, such as the construction of ships and submarines. To develop a companionable wire for welding of Ni-Mo low alloy steel, the amount of the alloying elements in a wire is increased to toughen of weld metal, the wire itself has high strength so that the wire is hardened at the wire drawing, making the wire production difficult. In order to avoid the problems related to the solid wires, various flux cored wires have been developed. In this work, the effect of flux basicity index and heat input on chemical composition, oxygen-nitrogen analysis, mechanical properties and microstructure of Ni-Mo low alloy steel welded by SAW welding using flux cored wires are presented along with the effect of flux cored wire and basicity index on deposition rate.

The effects of alloying elements, Cr and Si, and the conditions of hot-dip galvanizing on the aging behaviors and their related tensile and torsional properties in cold drawn hyper-eutectoid steel wires were investigated. The Cr and Si additions were found to increase tensile strength, but decrease the limit of drawing strain without delamination in cold drawn steel wires. The Cr and Si additions encouraged the suppression of age hardening and age softening during annealing. The increased amount of deformation in cold drawn steel wires made age hardening occur at the lower annealing temperature and shorter annealing time, and expanded the delamination region to high temperature during annealing. The additions of Cr and Si did not show the noticeable improvement of tensile strength without delamination in cold drawn steel wires, but increased the upper limit of tensile strength without delamination in cold drawn and annealed steel wires.

In the electroplastic wire drawing process, the drawing force is reduced with the application of an electric current. The drawing force drop is the result of a combination of various factors. The objective of this article is to build a theoretical formula between the electroplastic effect and the drawing force. Based on existing electroplastic effect theory and experimental results, the mechanical characteristics of the electroplastic wire drawing process are analyzed, and a mathematical model of the electroplastic drawing force is established. This calculation method takes into account both the influence of electroplastic effect on metal’s flow stress and the change of the wire temperature with an electric current applied. Finally, the results of experiment and theoretical calculations are compared and analyzed. The results of this paper will provide a reference for the theoretical calculation and simulation study of the electroplastic effect in engineering applications.

This paper presents the PullWorks software, an expert system that has been developed for the fast and simple design with the aim of optimizing the multi-stage copper wire drawing process. This software has been implemented applying the analytical method and complemented with the results of a series of experimental tests for the correct characterization of the processed material. The expert software system created has been used to model a real drawing line (Cunext Copper Industries S.L., Cordoba, Spain), with a production capacity of more than 30,000 t/year and an installed capacity of 1700 kW. PullWorks has made it possible to propose two modifications in the industrial process reducing its energy consumption by at least 1260 MWh/year: thanks to a reduction in the number of stages in the process lines (from 8 to 5, in the roughing line; from 19 to 13 in finishing) and by the elimination of the annealing treatment between them. The validity of these results has been verified through of the corresponding simulations made by the software Deform2D by means of which the numerical method of the finite elements analysis has been applied, and the solution was partially checked in the industrial process in operation.

Near eutectoid fully pearlitic wire rod (5.5 mm diameter) was taken through six stages of wire drawing (drawing strains of 0 to 2.47). The as-drawn (AD) wires were further laboratory annealed (LA) to re-austenitize and reform the pearlite. AD and LA grades, for respective wire diameters, had similar pearlite microstructure: interlamellar spacing (lambda) and pearlite alignment with the wire axis. However, LA grade had lower hardness (for both phases) and slightly lower fiber texture and residual stresses in ferrite. Surprisingly, essentially identical tensile yield strengths in AD and LA wires, measured at equivalent spacing, were found. The work hardened AD had, as expected, higher torsional yield strengths and lower tensile and torsional ductilities than LA. In both wires, stronger pearlite alignment gave significantly increased torsional ductility.

In this work, a two-stage surrogate assisted optimization technique is proposed for optimizing a non-circular drawing (NCD) sequence. The objective function was introduced to minimize inhomogeneity of the effective strain distribution at the cross-sections of the drawn wire which could deteriorate its delamination characteristics. The design variables introduced were die geometry and reduction of areas of the NCD sequence. Combination of Kriging (KG) models and support vector regression (SVR) which found to be an efficient technique in the literature is used as a surrogate model while a new circular sampling generation technique is proposed and applied leading to a two-stage surrogate assisted optimization strategy. The results revealed that using the proposed two-stage surrogate assisted optimization strategy can reduce surrogate model uncertainty within the same total number of training points compared to a traditional approach. The optimum results showed better effective strain homogeneity at the cross-section of the drawn wire than the original wire drawing (WD) process and NCD sequence with the same total reduction of area and less number of passes.

During cold drawing of pearlitic steel wire, the lamellar structure becomes gradually aligned with the drawing axis, which contributes to the ultra-high strength. A direct simulation about the mechanical behaviors and microstructural evolution of pearlitic lamellae was presented. A representative volume element (RVE) containing one pearlitic colony was established based on the real transmission electron microscope (TEM) observation. The deformation of pearlitic colony during tension, shear and wire drawing were successfully simulated. The numerical results show that this metallographic texture leads to a strong anisotropy. The colony has higher yielding stress when the lamellar direction is parallel and perpendicular to the tensile direction. The lamellar evolution is strongly dependent on the initial direction and deformation mode. The formation of typical period shear bands is analyzed. In the wire drawing, the pearlitic colony at the sub-surface experiences a complex strain path: rotation, stretching along the die surface, and rotation back.

Fixed abrasive wires, electroplated wire saws, and resinoid wire saws are widely used to slice brittle materials. However, poor wear resistance becomes a crucial issue when these tools are used in hard brittle materials, such as single-crystal silicon carbide (SiC). This problem was addressed in this study through the development of brazed diamond wires. The production method and the slicing performance of brazed diamond wire were systematically investigated. A complete wire manufacturing line was developed to fabricate brazed diamond wire. Effect of brazing temperature on diamond grain graphitization damage was experimentally researched. The results indicated that the diamond grain graphitization damage was weakened or avoided with the optimized brazing temperature and holding time. Effect of brazing temperature on core wire mechanical property was evaluated by tensile strength, breaking twist strength, and repeated bending strength. Long brazed diamond wires were produced with optimized produce parameters for various brazing alloys. Sawing experiments on single-crystal SiC reveal that the slicing ability and slicing efficiency of the self-made brazed wire saws were better than those of commercial electroplated wire saws.

Results are given for research to develop scientifically based process solutions to improve quality characteristics of rolled coils cooled in a two-stage Stelmor line ensuring effective metal microstructure and processing properties for wire and wire products. An increase in welding rod ductility is achieved by limiting the steel’s strengthening element content, effective application of the boron to nitrogen ratio, and optimization of two-stage cooling, ensuring the formation of large ferrite grain size with rolling heat during isothermal soaking, thereby minimizing the formation of non-ductile structural components (bainite and martensite). For high-carbon wire rod used in the manufacture of concrete sleepers, it is necessary to achieve the fine pearlite structure of point 1 (GOST 8233–56) that is provided by alloying steel with boron, vanadium, and/or chromium, and also use of fan cooling. This structure is the optimum from the point of view of metal ductility and strength.

In this paper, characteristics of residual stress in pearlitic steel wire drawn by a non-circular drawing (NCD) sequence with two processing routes, NCDA and NCDB, were experimentally and numerically investigated up to the 12th pass in comparison with conventional wire drawing (WD). For experimental investigation of the axial residual stress at the surface of the drawn wire, destructive (deflection) and non-destructive methods were employed. According to the experimental results, axial surface residual stress of the drawn wire by the NCD sequence was lower and more homogeneous compared to the conventional WD. Based on the elasto-plastic numerical simulation results from the surface to the center of the drawn wire using a commercial DEFORM-3D, an empirical relationship between residual stress and reduction of area was determined to predict the residual stress evolution in the multi-pass WD, NCDA, and NCDB, in that order. From the results of this investigation, it can be construed that the NCD sequence, especially the NCDB, might be helpful in improving the residual stress characteristics of pearlitic steel wire to improve its mechanical behavior and service life.

A combined multipass hot and cold drawing process was implemented to manufacture ultra-thin wires of the magnesium alloy MgCa0.8 with a final diameter of 0.05 mm. Numerical simulations were applied to design the drawing process of 40 passes regarding the microstructure evolution. To parametrize the model, in situ tensile tests were performed. Analysis of the MgCa0.8 wires featuring diameters below 0.1 mm revealed no intergranular crack initiation. The grain size of the ultra-thin wires is within the range of 30–500 nm with grains elongated in the drawing direction. The fine-grained microstructure provides high mechanical strength properties.

Recently developed accumulative angular drawing (AAD) combined with wire drawing (WD) and wire flattening (WF) processes were employed to effectively induce severe plastic deformation (SPD) effects into drawn wires. The influence of combined effects of area reduction, bending, shearing, and burnishing on the accumulated deformation energy and microstructural inhomogeneities in the microalloyed steel (b.c.c.) wires has been discussed with respect to possibilities of formation of ultrafine-grained and multilayered structures in subsequently drawn and flattened wires. However, the main challenge in the present study was to support and extend experimental research on hardening mechanisms and inhomogeneous deformation energy accumulation during investigated combined forming process by numerical simulation. One of the efficient solutions to that task is development of multiscale numerical model based on digital material representation (DMR) concept, capable of explicit recreation of microstructure morphology of investigated materials as well as its further evolution with respect to complex macroscopic processing conditions. As an outcome, it was demonstrated that the presence of precipitates in the severally deformed and inhomogeneous ferrite can be not only the key factor in strengthening process but can also directly influence the grain refining process. The presented study provides a set of evidence and inspiration for introducing the controlled inhomogeneity of deformation as a tool to produce advanced structural materials.

According to the demand of stream function, a twin parabolic die as a streamline for wire drawing was designed and its kinematically admissible velocity field was then developed. Using the specific energy rate of MY (mean yield) criterion, the mathematical expression of internal deformation energy rate is obtained. Through surface integral of the proposed velocity field, the friction energy rate is also determined. Based on upper bound method, an analytical solution of drawing force is ultimately obtained. The effect of percentage reduction and die semi-angle on the drawing force are discussed. Comparison shows that the calculated drawing forces of the proposed die closely match its numerical drawing forces, and are the lowest compared with those based on conical die, hyperbolic die and elliptic die.

The effect of reduction of area (RA), 10%, 20%, and 30%, during wire drawing on the inhomogeneities in microstructure and mechanical properties along the radial direction of Fe-Mn-Al-C twinning-induced plasticity steel has been investigated. After wire drawing, the deformation texture developed into the major and minor duplex fiber texture. However, the texture became more pronounced in both center and surface areas as the RA per pass increased. It also shows that a larger RA per pass resulted in a higher yield strength and smaller elongation than a smaller RA per pass at all strain levels. Although inhomogeneities in microstructure and mechanical properties along the radial direction decreased with increasing RA per pass, there existed an optimum RA per pass for maximum drawing limit. Insufficient penetration of strain from surface to center at small RA per pass (e.g., 10%) and high friction and unsound metal flow at large RA per pass (e.g., 30%) all resulted in heterogeneous microstructure and mechanical properties along the radial direction of drawn wire. On the other hand, 20% RA per pass improved the drawing limit by about 30% as compared to the 10% and 30% RAs per pass.

This paper investigated the wire tension change in high-speed wire electrical discharge machining (HSWEDM). The symmetry of the wire-winding mechanism and the resistance to the wire electrode on the upper and lower guide frames were considered the main causes of a non-even wire tension. Combined with the simulation model and the redesigned wire-winding mechanism, the adjusting wheel and the protection block were used to control the symmetry of the wire-winding mechanism and the resistance to the wire electrode on the upper guide frame. The wire tension was found to be capable of remaining stable in the machining process. The redesigned wire-winding mechanism can improve cutting stability and efficiency in large thickness cutting processes as well as the consistency of workpiece dimension in multi-cutting processes.

Wire electrical discharge machining (WEDM) is an important technology, which demands high-speed cutting and high-precision machining to realize productivity and improved accuracy for manufacturing hard materials. WEDM has experienced explosive growth and complexity of equipment as well as rising demand for the basic process tool (the wire electrode). Greater taper angles, thicker workpieces, automatic wire threading, and long periods of unattended operation make the selection of the ideal wire a much more critical basis for achieving successful operation. This paper focuses on the evolution of EDM wire electrode technologies from using copper to the widely employed brass wire electrodes and from brass wire electrodes to the latest coated wire electrodes. Wire electrodes have been developed to help user demand and needs through maximum productivity and quantity by choosing the best wire. In the final part of the paper, the possible trends for future WEDM electrode research are discussed.

Wire has traditionally been made from wire rod. Scale is removed from the surface of the wire rod before it is drawn through die plates (draw plates). Performing the drawing operation without the use of a die plate makes it possible to deform the wire rod without removing the scale, i.e., it creates a new process that combines descaling and drawing. The authors created an experimental unit with a kinematically determined amount of elongation in order to study the process of drawing without a die plate. They studied different parameters of the process of drawing wire rod without a die plate and compared it to traditional drawing.

Iron (Fe) is commonly found in aluminum (Al), but its contents are usually kept as low as possible, because the formation of intermetallic phases may induce fracture. In this study, high-pressure torsion (HPT) was used to control the microstructure in an Al-2 %Fe alloy in conjunction with wire drawing and an aging treatment, in order to improve not only their mechanical properties but also the electrical conductivity. It is shown that HPT processing of ring-shaped samples produced ultrafine grains with a size of ~150 nm in the matrix, while intermetallic phases were fragmented to nanosizes with some Fe fraction dissolved in the matrix. Semi-rings were extracted from the HPT-processed samples and swaged to a round section with 0.4-mm diameter. The HPT-processed sample was successfully drawn to a final diameter of 0.08 mm (25:1 ratio, 96 % reduction in area), whereas the sample without HPT processing failed after drawing to 0.117-mm diameter (12:1 ratio, 91 % reduction in area). The electrical conductivity increased to ~65 IACS % in the HPT-processed rings and to ~54 IACS % in the wires by aging for 1 h after the drawing.

The deformation of fully pearlitic steels during wire drawing has been investigated for both longitudinal section and transverse section by back-scattered electron imaging (BSEI), electron back-scattered diffraction (EBSD), and transmission electron microscope (TEM). The results show that a large number of deformation bands (DBs) composed of a mixture of kink-like bands and shear-like bands were observed both in the longitudinal section and the traverse section of the drawn wires. The formation of such bands involves two aspects: heterogeneous deformation in the scale of pearlite colonies and instability of ferrite-cementite interfaces due to stress concentration during wire drawing. The development of such bands in fully pearlitic steels dominates the formation of metallographic texture, reduces the pearlite interlamellar spacing and promotes the development of fiber crystalline texture of ferrite matrix during wire drawing.

The powder-cored wire drawing process is simulated using the finite-element method. To describe the behavior of the powder core, a plasticity model of porous and granular media with planar defects is proposed. The model takes into account bimodulus behavior and susceptibility to dilatancy. The densification of the powder core after one and six wire-drawing passes is studied. Substantial transverse nonuniformity in the density distribution of the powder core is found. The dependence of the densification behavior of the powder core on the initial porosity and fraction of planar effects is established.

Cold formed semi-finished products face an increasing demand from industry as they can be manufactured to dimensional precision and high surface quality. Products from cold formed bar, on the other hand, may contain inhomogeneous distributions of mechanical properties and residual stresses which arise from the elastic response of the material to an inhomogeneous distribution of elastic–plastic strains. These material properties may cause distortion in further manufacturing operations, and consequently, precision of components then could be reestablished at higher costs only. X-ray diffraction residual stress analysis, for example, is misleading if only slices or cross sections of a bar or a component are considered and residual stress fields and their variations are neglected. Automotive products generally are cut from drawn bars, and local differences in microstructure, mechanical properties and residual stress states are increasing the danger of dimensional changes out of a specified range. Cold-drawn bars were manufactured with different drawing angles and uncoated and TiCN-coated dies. Surface and subsurface properties were investigated along the length and around the periphery of drawn bars. Differences in material states, those affected by the contact zone and those related to the elastic–plastic deformation of the drawing process, were observed. The variation of surface residual stresses of up to a factor of 2 can be correlated with locally different friction coefficients and slip stick effects. As subsurface material states (residual stresses and strain hardening) do not show a significant variation around the periphery and along the length of bars, the effects of geometry variations of hot rolled bar, the effect of a not perfectly concentric bar at the die entrance and/or the level of pre-straightening ahead of drawing are assumed to be of minor importance, compared to the high level of plastic strain involved in cold drawing. The local properties identified here will lead to a higher degree of dimensional scatter of individual automotive components cut from these long cold-drawn bars.

Diamond wire is widely used for stone cutting; it is typically employed to extract a block in quarry and to square the block in a machining company. In particular, the frames to square or to cut the blocks present many technological limits, such as the high costs of the diamond wire, the frequent break of the diamond wire during cutting, the poor quality of cut surfaces, and the dangerous process and productivity lower than that of the same tool used in a quarry. The present work shows an innovative prototype machine to cut by a diamond wire which overcomes the aforementioned technological limits. The developed machine has a bridge frame among which two pulleys move the diamond wire as regards the stone block according with the feed speed. The diamond wire moves on the two pulleys with a cutting speed. A tensile force is applied to the wire that twists it during the contact with the stone, instead of keeping it along a straight direction parallel to the foundation of the machine. The twisting of the diamond wire makes the use of the wire itself more productive and safer, since the wear of each single bead during cutting is more uniform. Moreover, the resulting specific pressure acts on each bead along the arc of contact with the cut block and increases along the cutting direction from the entrance to the exit of the contact with the stone. The increasing of the specific pressure causes a bending of the diamond wire during the contact with the stone. The developed prototype was provided with a sensory system to measure both the cutting power and the tensile force of the diamond wire during experimental tests. In this way it was possible to verify the functionality of the prototype plant and, in the same time, to evaluate the productivity of the implemented cutting process.

The evolution of morphology of pearlite and crystallographic texture of ferrite matrix in fully pearlitic steels during wire drawing were quantitatively investigated. The study revealed that a fiber structure of the pearlite morphology and a fiber texture of the ferrite matrix begin to take shape and develop gradually with increasing strain. The growth rates of the fiber structure and the texture are different in different regions within the wires with increasing drawing strain. There is a close relationship between the pearlite morphology and the crystalline texture during wire drawing. The pearlite interlamellar spacing (ILS) and thickness of cementite lamellae (Tθ) decrease gradually both in longitudinal and transverse sections. The definition of pearlite colony should be reconsidered for describing microstructure of the wire drawing deformed pearlitic steels.

This study develops a dieless drawing prototype machine for tube or wire drawing processes. The proposed dieless drawing machine is composed of three main parts: a supporting frame, a heating device, and a transmission system. A high-frequency heating apparatus serves as the heating source, and an infrared thermocouple is used to monitor the heating temperature. A servomotor moves the heating coils in the opposite direction to the drawing clamp table to control the relative speed and area reduction of the stainless steel tube workpiece. A series of experiments were conducted to test the effects of different relative speeds between the heating source and drawing clamp table. The maximal area reduction achieved was approximately 40 % of the initial cross-sectional area at a drawing speed of 0.8 mm/s. Finite element simulations were also conducted to analyze the formable regions at different relative speed ratios, drawing speeds, and heating temperatures. The study verifies the validity of the numerical model by comparing the area reductions and shape similarity of the drawn tubes to numerically predicted and experimentally measured values.