Experimental study of the simultaneous effects of severe plastic deformation and secondary radial strain on copper

Author(s):  
Seyyed Ehsan Eftekhari Shahri ◽  
Mohammad Amin Ranaei ◽  
Hossein Jamshidi ◽  
Elyas Rezaei

Due to the widespread use of copper wires in electrical power transmission, the need for raw materials with a homogeneous structure and high strength while maintaining their conductive properties is of high importance. The present study investigates the production of copper wire with improved mechanical properties and homogeneous microstructure due to its nanometre-sized structure. Therefore, the commercial pure copper specimens were subjected to severe plastic deformation (SPD) by means of equal channel angular pressing (ECAP) during four steps at ambient temperature. Due to the creation of a structure with elongated grains in the ECAP process, the deformed specimens were subjected to the direct extrusion operations; thus, a more homogeneous structure was created in them due to the appearance of a secondary radial strain. The obtained results indicate that by applying the simultaneous effects of SPD and direct extrusion on the microstructure, the mechanical properties such as strength and hardness have improved significantly, while the electrical conductivity of pure copper decreased slightly. The outcome can be used as an alternative to current methods for producing high-strength copper wires with suitable electrical conductivity properties.

2015 ◽  
Vol 153 ◽  
pp. 5-9 ◽  
Author(s):  
S.V. Dobatkin ◽  
J. Gubicza ◽  
D.V. Shangina ◽  
N.R. Bochvar ◽  
N.Y. Tabachkova

2016 ◽  
Vol 879 ◽  
pp. 1317-1322 ◽  
Author(s):  
Anna Mogucheva ◽  
Diana Yuzbekova ◽  
Tatiana Lebedkina ◽  
Mikhail Lebyodkin ◽  
Rustam Kaibyshev

The paper reports on the effect of severe plastic deformation on mechanical properties of an Al-4.57Mg-0.35Mn-0.2Sc-0.09Zr (in wt. pct.) alloy processed by equal channel angular pressing followed by cold rolling (CR). The sheets of the 5024 alloy with coarse grained (CG) structure exhibited a yield stress (YS) near 410 MPa and an ultimate tensile strength (UTS) of 480 MPa, while the YS and UTS of this material with ultrafine-grained (UFG) structure increased to 530 and 560 MPa, respectively. On the other hand, the elongation to failure decreased by a factor of 2 and 4 after CR and CR following ECAP, respectively. It was shown that dislocation strengthening attributed to extensive CR plays a major role in achieving high strength of this alloy. Besides these macroscopic characteristics, jerky flow caused by the Portevin-Le Chatelier (PLC) instability of plastic deformation was examined. The formation of UFG structure results in a transition from mixed type A+B to pure type B PLC serrations. No such effect on the serrations type was observed after CR.


2010 ◽  
Vol 667-669 ◽  
pp. 909-913 ◽  
Author(s):  
Oleksandr Davydenko ◽  
Victor Spuskanyuk ◽  
Viktor Varyukhin

A new approach is proposed to control the processes of billets plastic deformation during metal treatment by the methods of severe plastic deformation (SPD). High strength and plasticity have been attained for the processed copper billets after multiple repetitions of equal channel angular hydroextrusion (ECAH) and direct hydroextrusion (HE) techniques and with ECAH and HE implementation in the fractional mode. The combined SPD treatment including ECAH, HE and drawing (D) provided for fire refined tough pitch copper (Cu-FRTP) the ultimate tensile strength =686 MPa, the elongation to failure =2% and the electrical conductivity (EC) at a level of 86.4% IACS and for oxidant free copper (Cu-OF) =576 MPa, =1.9%, EC=96.7% IACS in the 0.5 mm diameter wire. Such treatment is efficient due to the alternative schemes of deformation, the fractional mode and the optimum degrees of plastic deformation and periodic creation of favorable conditions for relaxation and dynamic recrystallization processes in the material.


2009 ◽  
Vol 67 ◽  
pp. 53-58
Author(s):  
V. Anil Kumar ◽  
M.K. Karthikeyan ◽  
Rohit Kumar Gupta ◽  
P. Ramkumar ◽  
P.P. Sinha

Severe plastic deformation processes (SPD) are gaining importance as advanced materials processing techniques and hold immense potential in obtaining ultra fine-grained high strength materials. Among the SPD techniques, Equal channel angular pressing (ECAP) has its own merits to produce materials with ultra fine grains in bulk with better mechanical properties. The material deforms with high level of plastic strain inside the channel resulting in grain refinement of the output material with improvement in mechanical properties. A very viable die configuration was conceptualized and die was made with 1200 channel angle. Processing of 25 mm dia. of Al alloy AA2219 at room temperature was successfully carried out and grain refinement was observed. The mechanism of grain refinement has been studied using optical and transmission electron microscopy (TEM). It was observed that low energy dislocation structure (LEDS) forms concurrently with sub-grain structure due to dislocation rearrangements, which provide stability to the evolving sub-grain structure. Dislocation mobility is hindered by the presence of precipitates and / or intermetallic dispersoids present in the matrix and results in presence of dislocations in grain interiors. The pile up of dislocations at intermetallic dispersoids was confirmed from the dark field TEM micrographs. Present paper describes the experimental procedure and followed to attain severe plastic deformation through ECAP. Increase in hardness as well as refinement in the grain size after 5-passes have been discussed in light of extensive optical and TEM. The mechanisms of grain refinement to achieve nano-grained structure and strengthening accrued from the grain refinement through ECAP has been discussed.


2010 ◽  
Vol 667-669 ◽  
pp. 943-948 ◽  
Author(s):  
Veronika Polyakova ◽  
Irina P. Semenova ◽  
Ruslan Valiev

This work is devoted to enhancement of strength and ductility of the Ti-6Al-7Nb ELI alloy, which is less harmful from medical point of view for human body in comparison to Ti-6Al-4V. It has been demonstrated that formation of an ultrafine-grained structure in the alloy with the help of equal-channel angular pressing in combination with heat and deformation treatments allows reaching high strength (UTS = 1400 MPa) and sufficient ductility (elongation 10 %).


Author(s):  
D. Azimi-Yancheshmeh ◽  
M. Aghaie-Khafri

ECAP is one of the Severe Plastic Deformation methods for reducing the grain size. With this process we can achieve ultrafine grains and consequently high strength. In this study, ECAP process was done on Al-Fe-Si alloy. This alloy was considered because of Fe effect on refining grain size. All samples were ECAPed into 1 pass in ECAP mold with 2 equal channels (1 cm × 1 cm) with 90 degree between them. By this method, around 1.05 as strain was applied on each samples. ECAPed specimens were heat treated (Semisolided) in different times and temperatures for achieving good toughness. Compression and hardness tests were done for finding the mechanical properties. As a result of these test, specimens that tolerate both ECAP and Semisolid have better toughness and strength than received and only ECAPed samples. Based on the microstructural evaluations spheroid solid phase was observed in the Semisolid specimen.


2015 ◽  
Vol 813-814 ◽  
pp. 161-165
Author(s):  
M. Sadhasivam ◽  
T. Pravin ◽  
S. Raghuraman

The need for super-plasticity and high strength leads to the development of Severe Plastic Deformation technique. The strength of the material is directly dependent upon the grain size of the material. So, there is a need for producing Ultra-Fine Grain microstructure (UFG). UFG material is the material with very small grain size in the range of sub-micrometre. Application of severe plastic deformation, imparts extremely high strain. Equal channel angular pressing (ECAP) is a severe plastic deformation process in which the metal specimen is pressed through an angular channel of equal cross section. The material is subjected to shear deformation and strain is imparted in the specimen. Geometric parameters such as channel angle and corner angle play a major role in grain refinement. Aluminium (Al) specimens are subjected to undergo severe plastic deformation. Since, the strength of Al is not high, other materials are added in order to enhance its mechanical properties by matrix work hardening. Copper (Cu) along with Al shows increase in its strength and also in hardness. An attempt is made with Aluminium and copper, blended in the ratio 95:5 by weight with the main objective to study the Tensile strength, Hardness and Percentage Elongation properties of the specimen.


Materials ◽  
2020 ◽  
Vol 13 (5) ◽  
pp. 1116
Author(s):  
Alena Michalcová ◽  
Dalibor Vojtěch ◽  
Jaroslav Vavřík ◽  
Kristína Bartha ◽  
Přemysl Beran ◽  
...  

Severe plastic deformation represented by three passes in Conform SPD and subsequent rotary swaging was applied on Ti grade 4. This process caused extreme strengthening of material, accompanied by reduction of ductility. Mechanical properties of such material were then tuned by a suitable heat treatment. Measurements of in situ electrical resistance, in situ XRD and hardness indicated the appropriate temperature to be 450 °C for the heat treatment required to obtain desired mechanical properties. The optimal duration of annealing was stated to be 3 h. As was verified by neutron diffraction, SEM and TEM microstructure observation, the material underwent recrystallization during this heat treatment. That was documented by changes of the grain shape and evaluation of crystallite size, as well as of the reduction of internal stresses. In annealed state, the yield stress and ultimate tensile stress decreased form 1205 to 871 MPa and 1224 to 950 MPa, respectively, while the ductility increased from 7.8% to 25.1%. This study also shows that mechanical properties of Ti grade 4 processed by continual industrially applicable process (Conform SPD) are comparable with those obtained by ECAP.


Metals ◽  
2020 ◽  
Vol 10 (6) ◽  
pp. 831
Author(s):  
Yang Li ◽  
Zhengtong Lu ◽  
Tingchao Li ◽  
Dalei Li ◽  
Jinsheng Lu ◽  
...  

In this study, two innovative surface severe plastic deformation (SSPD) methods, namely abrasive waterjet peening (AWJP) and ultrasonic nanocrystal surface modification (UNSM), were applied to a 304 stainless steel to improve the mechanical behavior. The surface roughness, microstructure, residual stress, hardness, and tensile mechanical properties of the alloy after the two SSPD treatments were studied systematically. The results show that both the AWJP and UNSM treatments have greatly positive effects on the mechanical-properties improvements by successfully introducing a hardening layer. Especially the UNSM-processed specimen possesses the most outstanding comprehensive mechanical properties (high strength with the comparable ductility). The yield strength with the UNSM treatment is 443 MPa, corresponding to the 109% and 19% improvements, as compared to that of the base (212 MPa) and AWJP-treated specimens (372 MPa). The results can be attributed to a much thicker hardening layer (about 500 μm) and a better surface integrity with lower roughness (Ra: 0.10 μm) formed by the UNSM technique.


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