The engineering application of the electroplastic effect in the cold-drawing of stainless steel wire

doi:10.1016/S0924-0136(02)01091-9

Journal of Materials Processing Technology

Volume 137, Issues 1–3, 30 June 2003, Pages 96-99

https://doi.org/10.1016/S0924-0136(02)01091-9 Get rights and content

Abstract

The application of electroplastic processing technology to the cold-drawing of steel wires was investigated. It is shown that the drawing stress was decreased by about 20–50% with the application of electric current pulses. The plasticity of the material had been significantly improved concurrently. With the application of electric current pulses, not only can a better surface quality of the wire be gained but also the wire can be drawn from its original diameter of 1.6 mm to a diameter of 0.40 mm, with good surface quality of the wire, without any annealing treatment. The mechanism of the electroplastic effect (EPE) can be explained as being that with the introduction of the current pulses, the dislocations in the materials can been de-pinned and distributed homogeneously. Thus, the strain in the crystals is decreased and the formation of the strain-induced martensite is delayed.

Introduction

The electroplastic effect (EPE) is the phenomenon in which the flow stress in a straining test is affected significantly by the application of a high density current pulses (10³–10⁴ A/mm²). Conrad et al. [1], [2], [3], [4] found such EPE phenomenon in various materials. Furthermore, it has been claimed that such current pulses can lead to improvement in metal-working operations [5].

The authors have investigated the effect of current pulses on the plastic properties of materials in the wire-drawing process. A substantial decrease of drawing force and a good improvement of the elongating ratio has been found [6]. In this paper, a more detailed investigation was made of such EPE phenomenon on the mechanical and magnetic properties and the microstructure on the surface of the cold-drawn wire.

Section snippets

Experimental work

A schematic illustration of the drawing system is presented in Fig. 1. The material used in this experiment was austenitic stainless steel 1Cr18Ni9, with a original diameter of 1.6 mm and in the pristine softened state. The current pulses were applied at the front and the back of the wire-drawing die, the latter having a half-angle of the cone of α=11.5°. The wire was first drawn without current and then with the application of current pulses so as to compare the effect of the current pulses on

The drawing force and the mechanical properties

With the application of the current pulses to the wire during drawing process, the drawing force decreased compared to conventional wire drawing, Fig. 2 shows that the drawing stress has decreased by about 50%. Simultaneously, the mechanical properties of the wire have changed greatly (Table 1).

Magnetic properties of the wire

From the data on magnetic properties of the wire with and without the application of current pulses, It is found that with the introduction of the current pulses, the saturated magnetization Bs has been

Discussion

From the macro-morphologic images of the wire, it is found that the wire drawn without current pulses has a lot of the above-mentioned “knots”, which can be seen with the naked eye, at the surface of the wire. This means that the surface quality will not be acceptable in factory production, and an annealing treatment will be needed, but as mentioned the wire drawn with current pulses has no such kind of “knots” (Fig. 4). The reason of the formation of such “knots” is that during the

Conclusions

1.
With the application of electric current pulses to the cold-drawing process of 1Cr18Ni9, the drawing stress will be decreased to about 50% compared with the conventional wire-drawing process. Also, the plasticity of the wire is improved.
2.
The wire drawn with electric current pulses has a better surface quality than that drawn by the conventional process.
3.
Numerous ferromagnetic phases are formed in the conventional wire-drawing process. With the introduction of the current pulses, however, the

Acknowledgements

This project is supported by the National Nature Science Foundation of China.

References (8)

H. Conrad et al.
Effect of Electric current pulses in the recrystallization of copper
Scripta Metall.
(1983)
A.F. Sprecher et al.
On the temperature rise associated with the electroplastic effect in titanium
Scripta Metall.
(1983)
A.F. Sprecher et al.
On the mechanisms for the electroplastic effect in metals
Acta Metall.
(1986)
Y. Di et al.
Influence of an electric field in the plastic deformation of polycrystalline NaCl at elevated temperature
Acta Mater.
(1998)

There are more references available in the full text version of this article.

Cited by (100)

Energy field assisted metal forming: Current status, challenges and prospects
2023, International Journal of Machine Tools and Manufacture
To meet the various and critical manufacturing requirements including high precision, low cost, good manufacturability, and more demanding from product service and performance aspects such as high performance, light-weight, less energy consumption and low carbon emissions in today's era of rapid product development with short product life circle, it is crucial to re-innovate and re-invigorate metal forming technologies and enable it to play an even more important role in manufacturing arena. Historically, introducing new kinds of energy fields into the forming process drives the innovative advance and rejuvenating of forming technologies due to the physically interactive mechanisms of energy field and certain material deformation behaviors such as thermal-mechanical coupling effects. In this paper, a classification of energy-aided metal forming processes is orchestrated and presented, and three kinds of energy-assisted metal forming technologies, viz., electrically-assisted forming, ultrasonic vibration assisted forming, and electromagnetic field supported forming, are reviewed and delineated as they are currently receiving a widespread attention with promising application potentials. In this paper, the physical essence and the effects of these introduced energy fields on deformation behavior, process performance, microstructure evolution are elucidated and analyzed. The constitutive modeling of these forming processes is recapitulated, and the newly established energy field assisted metal forming technologies are exemplified and discussed. Based on the advantages and limitations of these unique metal forming processes assisted by additional energy fields, the process capacity and application potentials are unraveled and examined. Finally, from the aspects of exploring physical mechanisms, establishing high-fidelity models, coupling the multiple energy fields, and developing intelligent equipment and realizing these forming processes, the current challenges and future prospects were discussed, summarized and articulated in such a way to present a panorama of the research, development and application of the energy-assisted forming technologies.
Understanding the microstructure evolution and mechanical behavior of titanium alloy during electrically assisted plastic deformation process
2023, Materials Science and Engineering: A
Titanium alloys are widely used in aerospace, petrochemical, and automobile industry due to their outstanding mechanical properties. However, the formability/plasticity of most titanium alloys at room temperature is relatively poor, and a large amount of energy is needed to manufacture them. In this study, the electrically assisted plastic deformation (EAPD) process is explored in a titanium alloy – TC11, to investigate how it can be used to enhance its formability/plasticity. A systematic study was conducted on the mechanical behavior and microstructure evolution of the TC11 during the EAPD process under different current densities (5–15 A/mm²) and strain rates (10⁻³-10⁻¹s⁻¹). The effects of the pulse current on the yield strength and microstructure of the titanium alloy TC11 are investigated. We found that the yield strength of the TC11 titanium alloy decreases with the increment of current density and the decrease of strain rate, suggesting that pulse current can improve the formability/plasticity of TC11 titanium alloy while reducing energy consumption during manufacturing. With the help of EBSD, TEM, and HAADF-STEM, we were able to characterize the phases refinement, dislocation annihilation, and element diffusion in the alloy. This phenomenon was explained by the recrystallization of the β phase during the EAPD process. Furthermore, the constitutive equations for the TC11 titanium alloy during the EAPD process have been formulated. The deformation stress predicted by the constitutive model agrees well with the experimental data. This study provides valuable insight into the mechanical behavior and microstructure evolution of the TC11 titanium alloys during EAPD.
Plastic deformation mechanism transition with solute segregation and precipitation of 304 stainless steel foil induced by pulse current
2022, Materials Science and Engineering: A
Stainless steel ultra-thin strip has become a hotspot because of its high added economic value. Reducing the deformation resistance during rolling is an effective and economical way to break through the minimum thickness limit of foil strips. And the dynamic softening effect of electroplastic effect provides a possible solution. However, the influence mechanism of electric pulse on stainless steel foil needs to be fully explored. In this work, the effects of pulse current with various peak current densities on the mechanical properties and deformation mechanism of 304 stainless steel foil were investigated. Compared with the conventional tension, the flow stress and elongation of steel foil are reduced during electro-pulsing assisted (EA) tension. The current causes the stress-strain curve to fluctuate in a serrated manner. The above changes can be attributed to the promotion of dislocation slip and the solute precipitation induced by coupling effect of deformation and pulse current. Besides, the pulse current suppresses the transformation from austenite to martensite and promotes the dynamic recrystallization (DRX), leading to reduction of deformation resistance. However, the severe solute segregation forms hard and brittle CrC intermetallic compound, which enhances the grain boundary strengthening, worsens the grain boundary properties and induces the generation of crack sources, resulting in the drastic diminishment in the ductility and toughness of steel foil. But this phenomenon can be avoided by controlling the current density and the treatment time during the deformation process.
Large tensile plasticity in Zr-based metallic glass/stainless steel interpenetrating-phase composites prepared by high pressure die casting
2021, Composites Part B: Engineering
The ambient-temperature brittleness of bulk metallic glasses (BMGs) is a long-standing problem in materials engineering. Herein, we report a route to overcome this Achilles’ heel of BMGs via high-pressure die casting (HPDC) at a high filling rate and pressure to create bi-continuous interpenetrating-phase composites. Our results show that large tensile plasticity of 5.1% can be achieved in the Zr-based BMG/stainless steel interpenetrating-phase composite prepared by HPDC, which is superior to most of as-reported ex-situ secondary phase reinforced BMG composites. The excellent mechanical properties of the BMG composite mainly originate from excellent metallurgical bonding between matrix and reinforcement as well as high efficiency suppression of shear band propagation by three-dimensional metal skeleton. Our findings provide a promising approach for developing cost-effective BMG composites suitable for industrial applications.
Force reduction by electrical assistance in incremental sheet-bulk metal forming of gears
2021, Journal of Materials Processing Technology
Producing load-adapted and functionally integrated components by flexible and resource efficient processes has gained importance within industries like the automotive sector in recent years. A promising new class of processes that enables a local adaption of the sheet thickness is Sheet-Bulk Metal Forming (SBMF). While the incremental procedure (iSBMF) only requires a moderate forming force, forming of high strength steels leads to a tool load resulting in a significantly reduced tool life. One approach to reduce tool loads is the utilization of the so called electroplastic effect (EPE). This study for the first time identifies the potential of the EPE on a temporary reduction of the forming force during the iSBMF of gears targeting an improvement of the tool life. The steel grades DC04 and HSM700 HD are characterized considering the EPE under uniaxial tension. Based on the characterization, the current density and temperature increase are modelled numerically and analytically for the incremental gear forming process. Moreover, the impact of EPE on strain hardening, grain texture and forming force is determined. By a local insulation of the forming tool based on a PVD coating and the application of an electrical current, a temporary force reduction of up to 55 % is observed whereas the strain hardening effect remains almost unaffected.
Optimizing phase interface of titanium carbide-reinforced copper matrix composites fabricated by electropulsing-assisted flash sintering
2021, Materials Science and Engineering: A
Full density TiC reinforced Cu matrix composites are fabricated by electropulsing-assisted flash sintering within 40 s. The addition of TiC significantly increases the hardness of the sintered sample. However, liquid Cu does not wet stoichiometric TiC, leading to a poor interface bonding strength between TiC and Cu, thus the tensile strength of the sintered sample is destroyed. By adding a small amount of Ti, the bonding strength of the interface between TiC and Cu can be effectively optimized, thereby the mechanical strength of the samples is improved, showing an increased hardness and tensile strength. Skillfully use the relationship between hardness and tensile strength curve to intuitively show the bonding strength of the micro interface from the macro characteristics. The reaction between dissolved Ti and stoichiometric TiC and the decomposition of stoichiometric TiC cause the formation of near-surface non-stoichiometric TiC_x (x < 1) with a marked metal-like electronic structure, which is the fundamental reason for the optimization of the interface bonding between TiC particles and Cu matrix. In the process of powder metallurgy, it is a promising strategy to enhance the composite materials by adjusting the stoichiometry of ceramic to form metal-like electronic structure and alter the bonding strength of ceramic/metal interface.

View all citing articles on Scopus

View full text