Cold Drawing Research Articles

Effect of History of Deformation and Heat Treatment on Cold Drawing Process Parameters and Final Properties of AISI 302 Stainless Steel Wire

Effect of History of Deformation and Heat Treatment on Cold Drawing Process Parameters and Final Properties of AISI 302 Stainless Steel Wire

Cover Picture: Materials and Corrosion. 6/2023

Cover: Corrosion of stainless steel ropes from a nominally austenitic alloy in seawater may result in hollow wires. This phenomenon was replicated by electrochemical tests and analysis of EBSD data indicates the susceptibility to such preferential axial corrosion being much more related to crystal orientation than to the amount of α'-martensite induced by cold drawing of the wires. Different production technologies may result in significantly diff erent corrosion behaviour. More detailed information can be found in: Paul Linhardt, Maria V. Biezma, Roland Haubner, Roman Schuster, Tomasz Wojcik, Hollow wire corrosion of stainless steel ropes in a marine mooring system and its relation to microstructure, Materials and Corrosion 2023, 74, 818.

Stress Corrosion Cracking of 316L Stainless Steel Additively Manufactured with Sinter-Based Material Extrusion.

This study investigates the stress corrosion cracking (SCC) behavior of type 316L stainless steel (SS316L) produced with sinter-based material extrusion additive manufacturing (AM). Sinter-based material extrusion AM produces SS316L with microstructures and mechanical properties comparable to its wrought counterpart in the annealed condition. However, despite extensive research on SCC of SS316L, little is known about the SCC of sinter-based AM SS316L. This study focuses on the influence of sintered microstructures on SCC initiation and crack-branching susceptibility. Custom-made C-rings were exposed to different stress levels in acidic chloride solutions at various temperatures. Solution-annealed (SA) and cold-drawn (CD) wrought SS316L were also tested to understand the SCC behavior of SS316L better. Results showed that sinter-based AM SS316L was more susceptible to SCC initiation than SA wrought SS316L but more resistant than CD wrought SS316L, as determined by the crack initiation time. Sinter-based AM SS316L showed a noticeably lower tendency for crack-branching than both wrought SS316L counterparts. The investigation was supported by comprehensive pre- and post-test microanalysis using light optical microscopy, scanning electron microscopy, electron backscatter diffraction, and micro-computed tomography.

Microstructure and second-phase strengthening mechanisms of CuTeCrY alloy

A CuTeCrY alloy prepared by homogenising annealing, hot extrusion, solution treatment, cold drawing, and a heat ageing treatment has tensile strength and electrical conductivity of 430 MPa and 78.9% IACS, respectively. Electron microscopy analyses show that a metastable CrCu2Te phase in the solid solution alloy is eliminated by the ageing treatment, and a 3–5 nm granular bcc-Cr phase becomes distributed in the matrix. This nanometre Cr second phase is the main contributor to the strengthening of the alloy whereas the second-phase strengthening effects of micrometre Cr and Te phases are weak.

On the strain stiffening and nanofiber orientation of physically crosslinked nanocellulose hydrogels

Nanocellulose hydrogels that consist of physically crosslinked nanofibrous networks with large amounts of interstitial water have many potential applications as structural materials in biomedical engineering. Quantifying the relationship between micro/nanostructures and their mechanical responses can provide some guidelines for the high-performance mechanical design of counterparts. To this end, we develop a modified physically based constitutive model for examining the effects of the micro/nanostructures of a nanofibrous network on the strain stiffening behaviors of nanocellulose hydrogels under stretching. In addition to the configurational entropy of cellulose nanofiber and mixing energy of water molecule, this theoretical model is particularly concerned with the contribution of the potential energy of hydrogen bond in a thermodynamics framework. Increasing the physical crosslinks between cellulose nanofibers or decreasing the content of water molecules in a certain range can enhance the strain stiffening behaviors of nanocellulose hydrogels. Relatively long and thin cellulose nanofibers have increased tensile strengths. The theoretical predictions are in good agreement with the relevant experimental results. We propose a fiber orientation model for quantifying the relationship between the nanofiber orientation degree and mechanical stretching. This model provides a theoretical foundation for fabricating anisotropic nanofibrous hydrogels via cold drawing.

Novel drawing technology for high area reduction manufacturing of ultra-thin brass wires

A significant increase in roughness of dieless-drawn wires due to the strain-induced roughness phenomenon has been documented. For small-diameter wires, even a slight surface relief creates stress concentrations that may contribute to the wire breakage during cold drawing. This, in turn, significantly limits the achievable diameter of the product and the efficiency of drawing process. The present study, however, demonstrates that reducing the wire roughness is possible by combining the dieless and conventional drawing methods. Thus, it is possible to improve the process workability threefold when compared to dieless drawing alone, and the product quality is simultaneously improved. In addition, the surface defects typical to the dieless-drawn wires have been significantly reduced, resulting in an increase in the wire strength. This new combined technology enables a significant reduction in the wire diameter and facilitates an economical large-scale production of ultra-thin wires. In addition, based on the classic drawing and dieless drawing process, a brass wire with a diameter of 0.017 mm has been manufactured. Six times thinner than a human hair, it is believed to be the thinnest long brass wire currently manufactured in the world.

Effect of deformation methods on microstructure, texture, and properties of a Cu–Mg alloy

The effect of cold working by drawing, rolling, or equal channel angular pressing (ECAP) on the microstructure, the texture, the mechanical properties, and the electrical conductivity of a Cu-0.25%Mg alloy was investigated. The plastic deformation led to the development of continuous dynamic recrystallization that was accompanied by strain-induced low-angle boundary formation and their transformation into high-angle boundaries with straining. The elongated grains evolved after drawing. Sheet rolling provided pancaked ultrafine grain formation assisted by the development of microshear bands. After ECAP almost equiaxed ultrafine grains formed readily inside the deformation microbands. The rapid kinetic of grain refinement assisted by geometric dynamic recrystallization during cold rolling and drawing led to the formation of ultrafine grains with transverse sizes of about 0.20 μm and 0.43 μm, respectively, while the grain size in the ECAP samples was 0.88 μm after total strain of 4. The deformation microstructures led to the significant strengthening resulting in the ultimate tensile strength of about 670 MPa after drawing or rolling to total strain of 4 and 625 MPa after ECAP to total strain of 9.2. Elongation slightly decreased from 21% to 19% after ECAP and dramatically degraded to 6–8% after drawing or rolling. A decrease in elongation was accompanied by a linear increase in the fraction of specific texture components. Electrical conductivity gradually decreased by about 6–10% IACS with straining regardless of deformation method. The strengthening mechanisms and the conductivity variation during deformation are discussed.

Shortening the manufacturing process of degradable magnesium alloy minitube for vascular stents by introducing cyclic extrusion compression

Due to its excellent biocompatibility and biodegradability, Mg and its alloys are considered to be promising materials for manufacturing of vascular sent. However, the manufacture of high-precision and high-performance Mg alloys minitubes is still a worldwide problem with a long manufacturing processing caused by the poor workability of Mg alloys. To solve this problem, the cyclic extrusion compression (CEC) was used to pretreat the billet by improving the workability of Mg alloys, finally shortening the manufacturing process. After CEC treatment, the size of grains and second phase particles of Mg alloys were dramatically refined to 3.2 µm and 0.3 µm, respectively. Only after three passes of cold drawing, the wall thickness of minitube was reduced from 0.200 mm to 0.135 mm and a length was more than 1000 mm. The error of wall thickness was measured to be less than 0.01 mm, implying a high dimensional accuracy. The yield strength (YS), ultimate tensile strength (UTS) and elongation of finished minitube were 220±10 MPa, 290±10 MPa and 22.0 ± 0.5%, respectively. In addition, annealing can improve mechanical property and corrosion resistance of minitubes by improving the homogeneity of the microstructure and enhancing the density of basal texture.

Superelastic stability of nanocrystalline Ni47Ti50Fe3 shape memory alloy

NiTi shape memory alloys have been widely explored because of their superelasticity. However, the application of conventional coarsed NiTi SMAs is limited by low superelastic stress and poor superelastic stability due to their low yield strength. In this study, nanocrystalline (NC) Ni47Ti50Fe3 alloy with average size is ∼15 nm was obtained by large deformation cold drawing and low temperature annealing. After ten cycles of loading (up to 6%)-unloading, the NC Ni47Ti50Fe3 alloy exhibited a high superelastic stress (1170 MPa)，low areduction rate of superelastic stress (12%) and small residual strain (0.66%). This overall performance is better than that of previous NiTi-based SMAs. We have suggested that this mainly stems from the synergistic reinforcement combines Fe element doping and high-density grain boundary.

Enhancing Mechanical Properties of Poly(p-phenylene sulfide) by Biaxial Deformation Using Cross-Rolling and Subsequent Annealing

The effect of thermal treatment on the mechanical performance of biaxially oriented poly(p-phenylene sulfide) by cold roll milling was studied. It was found that the ductility of the cross-rolled material could be further enhanced by annealing at temperatures above Tg and the yield strength could be enhanced by annealing at temperatures below Tg with a partial loss in ductility. Two-dimensional wide-angle X-ray diffraction patterns suggested a reduced crystallinity in the rolled material and showed that the crystal structure of the unrolled material could be partially recovered by annealing above Tg; however, scattering patterns adjacent to the crystalline reflections persisted with heat treatment. Modulated differential scanning calorimetry (MDSC) and broadband dielectric spectroscopy indicated that cross-rolling altered the kinetics of the cold-crystallization process. MDSC and dynamic mechanical analysis measured a reduction in Tg suggesting enhanced molecular mobility as an outcome of cross-rolling. After annealing at temperatures well beyond Tg, a large reduction in elongation to failure was observed, and the material could not cold draw. These results suggest that a two-stage process involving plastic deformation by roll milling followed by annealing treatment may be used to commercially produce high toughness and yield strength sheet products from commercially available resins.

Corrosion and tensile behavior of intercritically heat-treated and cathodically polarized prestressing steel wires

The effect of the intercritical heat treatments producing various martensite volume fractions on the corrosion and tensile behavior of the cathodically polarized prestressing steel wires has been investigated. Potentiodynamic polarization and constant extension rate technique (CERT) tests are conducted to clarify these effects and to determine the mode of failure of the prestressing steel wires since the presence of the martensite in the prestressing steel wire microstructure results in the failure and breakage during the corrosion and cold drawing. The electrochemical data measurements reveal that the intercritically heat-treated and cathodically polarized prestressing steel wires containing higher volume fractions of martensite exhibit the lowest corrosion potentials and current densities which indicate higher corrosion rates. A significant decrease in the tensile strength and ductility by the accelerated corrosion tests is observed in the intercritically heat-treated and cathodically polarized prestressing steel wire specimens containing higher martensite volume fractions. The fracture surfaces of the intercritically and cathodically prestressed steel wire specimens containing higher fractions of martensite of 68% exhibit a mixed mode of failure, i.e., quasi-cleavage and microvoid coalescence after potentiodynamic polarization. Moreover, the brittleness due to the residual stresses induced by the formation of martensite and the generation of the galvanic corrosion cell between the martensite and pearlite is noted to be increased with increasing the amount of martensite in the prestressed steel wire specimens.

Reduction of Residual Stresses in Cold Drawn Pearlitic Steel by a Soft Secondary Wire Diameter Reduction

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.

Microstructural, textural, and residual stress evolution alongside the magnetic properties through isothermal static recrystallization of cold-drawn Fe–Cr–Si–S–C ferritic high-alloy stainless steel and by JMAK modelling

The evolution of microstructures, textures, and residual stresses scale of cold-drawn (CD) 18%Cr ferritic stainless steels (FSS) round bars under isothermal static recrystallization annealing are investigated. As for determination of the new grains' formation, the size, growth, and orientation, as well as the nucleation of grains, alongside revealing the recrystallization fractions are studied by a mixed experimental and theoretical work. The recrystallization kinetics are calculated according to the Johnson-Mehl-Avrami-Kolmogorov theory. Electron backscatter diffraction (EBSD) analyses are applied for the actual specimens of an industrial wire drawing process with 20 and 35% reduction rates. The heat treatment has been implemented at three different set ratio temperatures of 0.65, 0.68, and 0.71, defining as a ratio between the temperatures of annealing and melting point (TRAM). According to the results, the nucleation is occurred at faster incubation time with higher temperature and reduction rate. The grain average size (AGS) increases gradually whereas the temperature increases. This is while the 0.71TRAM-scale annealed samples illustrate finer and more equiaxed recrystallized grains. Following recovery, recrystallized grains, and the grain growth, the overall varied AGS of 27–86 μm in the core region are achieved. Moreover, the JMAK model agrees well with the obtained experimental data. All in all, this 18Cr-FSS material is taken into account for the optimal industrial annealing production as well as the targeted material selection of the market applications. It is observed that the higher recrystallization leads the higher magnetic permeability, lower coercivity, and lower residual stresses compared to the unheated specimens.

Processability and structural evolution of round ingots of Al – 2 % Cu – 2 % Mn alloy during forming

This paper looks at the processability of round ingots of Al – 2% Cu – 2% Mn alloy during pressing, radial-displacement rolling and drawing. As a result of pressing combined with cross rolling, 9 mm round bars were obtained, which were then rolled and drawn into 0.5 mm wire. The wire was examined in its initial state and after different regimes of annealing. The paper shows that the cast structure contains a small amount (<2 vol. %) of eutectic particles Al2Cu and Al15(Fe,Mn)3Si2, which ensures a good deformation plasticity at the relatively low temperature of 300 oC and enables to produce 15 mm pressed round bars with a 94% reduction. In spite of considerable strain hardening, the bars displayed high processability when subjected to cold radial-displacement rolling and drawing. Thus, a 0.5 mm wire could be obtained with a total reduction of 99%. Mn-bearing dispersoids partially formed during pressing, which prevent softening during annealing. It is shown that the best combination of strength and plasticity is achieved after annealing at 350 oC, which indicates a rather high heat resistance. This experimental alloy can potentially be used as a basis for developing wrought alloys designed to produce round ingots on a commercial scale. Such ingots require no homogenization and can be used to produce a variety of deformed semi-finished products offering an optimum combination of mechanical performance and heat resistance.This research was funded under Grant No. 20-19-00249 by the Russian Science Foundation.

Bioabsorbable WE43 Mg alloy wires modified by continuous plasma-electrolytic oxidation for implant applications. Part I: Processing, microstructure and mechanical properties

In our work, a novel processing strategy for the continuous fabrication and surface modification of wires from Magnesium alloy WE43 by means of plasma-electrolytic oxidation (PEO) is presented. In the first step, wires with a strong basal texture and small grain size (≈ 1 μm) were manufactured by combined cold drawing and in-line stress-relief heat treatment steps that optimized the mechanical properties (in terms of strength and ductility) by means of annealing. In a second step, and to the best of our knowledge for the first time ever, the wires were continuously surface-modified with a novel plasma electrolytic oxidation process, which was able to create a homogeneous porous oxide layer made of MgO and Mg3(PO4)2 on the wire surface. While the oxide layer slightly diminished the tensile properties, the strength of the surface-modified wires could be maintained close to 300 MPa with a strain-to-failure ≈ 8 %. Furthermore, the thickness of the oxide layer could be controlled by immersion time within the electrolytic bath and was adjusted to realize a thicknesses of ≈ 8 μm, which could be obtained in <20 s. Our experiments showed that the chemical composition, morphology and porosity of the oxide layer could be tailored by changing electrical parameters. The combined cold drawing and heat treatment process with additional continuous plasma electrolytic oxidation processing can be upscaled to produce a novel generation of bioabsorbable Mg wires with optimized mechanical, degradation and biological performance for use in biomedical applications.

Double-diffusive Hamel–Jeffrey flow of nanofluid in a convergent/divergent permeable medium under zero mass flux

In the recent era, the nanofluid's transportation due to the Jeffrey–Hemal flow phenomenon (i.e., carrying fluid through a converging/diverging channel) has significant applications in numerous engineering and science technologies. Therefore, multi-disciplinary evolution and research motivated us to present current attempt. The aim of this attempt is to present Jeffrey–Hamel mechanism of the nanofluid through non-parallel channel under thermally balance non-Darcy permeable medium impacts. The nanomaterial is represented using the Buongiorno nanofluid model. The investigation also includes zero mass flux impacts as well as variable rheological fluid properties. The influences of temperature jump are also encountered in the current analysis. The governing flow expressions under the Jeffrey–Hemal analysis are made dimensionless utilizing the similarity variables. The dimensionless equations are then solved using the analytical scheme (homotopy method) and the obtained series solutions are convergent. The influences of the involved parameters on concerned profiles are investigated through graphs. Force of drag, Nusselt and Sherwood numbers are elaborated graphically. In this analysis, intensification in Prandtl number enhances the heat transfer rate whereas decrement is seen in heat transfer rate for larger thermal slip parameter. Further, mass diffusivity parameter adversely affects the mass transfer rate. The current analysis incorporates numerous industrial and technological processes including transportation, material synthesis, microfluidics, high-power Xrays, biomedical, solid-state lighting, microelectronics, scientific measurement, medicine, molten polymers extrusion via converging dies, cold drawing operation related to polymer industry etc.

Capping layer enabled controlled fragmentation of two-dimensional materials by cold drawing.

Cold drawing, a well-established processing technique in the polymer industry, was recently revisited and discovered as an efficient material structuring method to create ordered patterns in composites consisting of both cold-drawable polymers and brittle target materials. Such a high-yield and low-cost manufacturing technique enables the large-scale fabrication of micro-ribbon structures for a wide range of functional materials, including two-dimensional (2D) layered materials. Compared to the abundant phenomenological results from experiments, however, the underlying mechanisms of this technique are not fully explored. Here, supported by experimental investigation, finite element calculations, and theoretical modeling, we systematically study the effect of a capping layer on the controlled fragmentation of 2D materials deposited on polymer substrates during the cold drawing. The capping layer is found to prevent the premature fracture of the 2D thin films during elastic deformation of the substrate, when a specific requirement proposed by the theoretical model is satisfied. Controlled fragmentation is enabled in the necking stage due to the protective effect of the capping layer, which also influences the size of the resulting fragments. Flexible and stretchable electrodes based on 2D material ribbons are fabricated to demonstrate the effectiveness of the proposed roadmap. This study gives an accurate understanding of interactions between 2D materials, polymer substrates, and capping layers during cold drawing, and offers guidance for potential applications such as flexible electronics.

Relative Position of Plug and Die on Forming Accuracy of Shaped Tube by Cold Drawing

In the actual industrial production and manufacturing, tube drawing plays an extremely important role. In this study, a device with adjustable relative plug position is designed, the influence of relative plug position on the dimensional accuracy and the drawing force of drawn tube was investigated. The results show that different relative plug positions affect the inner and outer surface dimensions of the tube respectively. Therefore, the relative plug position can be distinguished according to the following rules in industrial production. When the position of the plug relative to the die is backward, the outer surface dimension of the drawn tube is qualified but the inner surface dimension is unqualified. When the position of the plug relative to the die is forward, the inner surface dimension of the drawn tube is qualified but the outer surface dimension is unqualified. The relative position of the plug is mainly due to the different radial force given to the tube by the plug and the die, resulting in the unqualified size of the drawn tube. When the plug is positioned backward relative to the die, the tube is subjected to the radial force of the plug first and then the radial force of the die. When the plug is positioned forward relative to the die, the tube is subjected to the radial force of the die first and then the radial force of the plug.

On the Use of Multi-Step Dies for Improving the Performance against Hydrogen Embrittlement of Cold Drawn Prestressing Steel Wires.

The main cause of in-service failure of cold drawn wires in aggressive environments is hydrogen embrittlement (HE). The non-uniform plastic strains and residual stresses generated after cold drawing play a significant role in the matter of HE susceptibility of prestressing steels. In this paper, a new and innovative design of the drawing scheme is developed, geared towards the reduction in both manufacturing-induced residual stresses and plastic strains. To achieve this goal, three innovative cold drawing chains (consisting in diverse multi-step dies where multiple diameter reductions are progressively carried out in a single die) are numerically simulated by the finite element (FE) method. From the residual stress and plastic strain fields revealed from FE numerical simulations, hydrogen accumulation for diverse times of exposure is obtained by means of FE simulations of the hydrogen diffusion assisted by stress and strains. Thus, an estimation of the HE susceptibility of the cold drawn wires after each process was obtained. Results reveal that cold drawn wire using multi-step dies exhibits lower stress and strain states nearby the wire surface. This reduction causes a decrease in the hydrogen concentration at the prospective damage zones, thereby improving the performance of the prestressing steel wires in hydrogenating environments promoting HE. Thus, the optimal wire drawing process design is carried out using special dies with several reductions per die.

Strengthening and toughening mechanisms of P-rich phase in Cu-4Sn-P alloy wire

The Cu-4Sn and Cu-4Sn-0.15P alloys with rod diameter of 12.5 mm were prepared and then cold drawn to 2.6 mm via multi-pass drawing. The microstructure evolutions, mechanical properties, and electrical conductivity of Cu-4Sn and Cu-4Sn-0.15P alloys were comprehensively analyzed using optical microscope, scanning electron microscope, tension test and electrical conductivity tester. As compared with the P-free alloy, the addition of P can form a new kind of P-rich phase in the Cu-4Sn alloy, and thus refine the casting microstructure via pinning the grain boundary. The toughening mechanisms of P-rich phases in Cu-4Sn-P alloy wires during cold drawing were investigated. With accumulative drawing strain, the spherical P-rich phase gradually changes into fibrous phases, which thus introduce obvious fiber reinforced strengthening. In addition, the distribution of P-rich phase also enhances the< 111 > texture, and promotes the growth of fragmentation zone. It contributes to an improved ultimate tensile strength and final elongation from 664.5 MPa and ∼ 0 % in Cu-4Sn alloy to 970.5 MPa and 1.53 % in Cu-4Sn-0.15P alloy. Finally, the conductivity for Cu-4Sn-0.15P decreases slightly owing to the intensified electron scattering with high amount of primary phase after the addition of P element.