The Work Softening Behavior of Pure Mg Wire during Cold Drawing

Several features of the metallurgy of superconducting composites of Nb-Ti in a Cu matrix are of interest. The cold drawing strains are generally of order 8-10, producing a very fine grain structure of diameter 30-50 nm. Heat treatments of as little as 3 hours at 300 C (∼ 0.27 TM) produce a thin (1-3 nm) Ti-rich grain boundary film, the precipitate later growing out at triple points to 50-100 nm dia. Further plastic deformation of these larger a-Ti precipitates by strains of 3-4 produces an elongated ribbon morphology (of order 3 x 50 nm in transverse section) and it is the thickness and separation of these precipitates which are believed to control the superconducting properties. The present paper describes initial attempts to put our understanding of the metallurgy of these heavily cold-worked composites on a quantitative basis. The composite studied was fabricated in our own laboratory, using six intermediate heat treatments. This process enabled very high critical current density (Jc) values to be obtained. Samples were cut from the composite at many processing stages and a report of the structure of a number of these samples is made here.

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Quantitative mechanisms behind the synchronous increase of strength and electrical conductivity of cold-drawing oxygen-free Cu wires

Journal of Alloys and Compounds ◽

10.1016/j.jallcom.2021.158759 ◽

2021 ◽

Vol 863 ◽

pp. 158759

Author(s):

P.F. Sun ◽

P.L. Zhang ◽

J.P. Hou ◽

Q. Wang ◽

Z.F. Zhang

Keyword(s):

Electrical Conductivity ◽

Cold Drawing

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Compaction of Cohesive Granular Material: Application to Carbon Paste

Materials ◽

10.3390/ma14040704 ◽

2021 ◽

Vol 14 (4) ◽

pp. 704

Author(s):

Zahraa Kansoun ◽

Hicham Chaouki ◽

Donald Picard ◽

Julien Lauzon-Gauthier ◽

Houshang Alamdari ◽

...

Keyword(s):

Numerical Simulation ◽

Mechanical Behavior ◽

Aluminum Industry ◽

Frequency Effect ◽

Strain Rates ◽

Cyclic Tests ◽

Carbon Paste ◽

Rheological Models ◽

Softening Behavior ◽

The Aluminum Industry

Carbon-like materials such as the anode and the ramming paste play a crucial role in the efficiency of the Hall–Héroult process. The mechanical behavior of these materials during forming processes is complex and still ill-understood. This work aimed to investigate experimentally the mechanical behavior of a carbon paste used in the aluminum industry under different loading conditions. For this purpose, experiments consisting of (1) relaxation tests at different compaction levels, (2) quasi-static cyclic tests at several amplitudes, (3) monotonic compaction tests at varied strain rates, and (4) vibrocompaction tests at different frequencies were carried out. The obtained results highlight some fundamental aspects of the carbon paste behavior such as the strain rate’s effect on the paste compressibility, the hardening-softening behavior under cyclic loadings, the effect of cycling amplitude on the stress state and the paste densification, and the frequency effect on the vibrocompaction process. These results pave the way for the development of reliable rheological models for the modeling and the numerical simulation of carbon pastes forming processes.

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Understanding the Strain Path Effect on the Deformed Microstructure of Single Crystal Pure Aluminum

Metals ◽

10.3390/met11081189 ◽

2021 ◽

Vol 11 (8) ◽

pp. 1189

Author(s):

Yingjue Xiong ◽

Qinmeng Luan ◽

Kailun Zheng ◽

Wei Wang ◽

Jun Jiang

Keyword(s):

Strain Rate ◽

Single Crystal ◽

Strain Path ◽

Mechanical Response ◽

Pure Aluminum ◽

Lattice Rotation ◽

Softening Behavior ◽

Theoretical Support ◽

Commercial Applications ◽

Electron Back Scattered Diffraction

During plastic deformation, the change of structural states is known to be complicated and indeterminate, even in single crystals. This contributes to some enduring problems like the prediction of deformed texture and the commercial applications of such material. In this work, plane strain compression (PSC) tests were designed and implemented on single crystal pure aluminum to reveal the deformation mechanism. PSC tests were performed at different strain rates under strain control in either one-directional or two-directional compression. The deformed microstructures were analyzed according to the flow curve and the electron back-scattered diffraction (EBSD) mappings. The effects of grain orientation, strain rate, and strain path on the deformation and mechanical response were analyzed. Experimental results revealed that the degree of lattice rotation of one-dimensional compression mildly dependents on cube orientation, but it is profoundly sensitive to the strain rate. For two-dimensional compression, the softening behavior is found to be more pronounced in the case that provides greater dislocations gliding freeness in the first loading. Results presented in this work give new insights into aluminum deformation, which provides theoretical support for forming and manufacturing of aluminum.

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