Mechanics of controlled fragmentation by cold drawing

2021 ◽  
pp. 104726
Author(s):  
Dong Li ◽  
Zhixun Wang ◽  
Ming Chen ◽  
Lei Wei ◽  
Huajian Gao
Keyword(s):  
Cold Drawing

Microstructure Development in a High Current Density NbTi Superconducting Composite

1985 ◽  
Vol 43 ◽  
pp. 186-189
Author(s):  
P. J. Lee ◽  
D. C. Larbalestier
Keyword(s):  
Current Density ◽  
High Current Density ◽  
Cold Drawing ◽  
Heat Treatments ◽  
Grain Structure ◽  
Fine Grain ◽  
Boundary Film ◽  
Quantitative Basis ◽  
Cold Worked ◽  
Very High

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.

Cold drawing of stainless steel tubes on a short mandrel

Metallurgist ◽  
1972 ◽  
Vol 16 (3) ◽  
pp. 202-204
Author(s):  
P. I. Chuiko ◽  
V. N. Kolesnikov ◽  
G. A. Savin
Keyword(s):  
Stainless Steel ◽  
Cold Drawing ◽  
Steel Tubes

Variation of Residual Stresses in Drawn Copper Tubes

2008 ◽  
Vol 571-572 ◽  
pp. 21-26 ◽  
Author(s):  
Adele Carradò ◽  
D. Duriez ◽  
Laurent Barrallier ◽  
Sebastian Brück ◽  
Agnès Fabre ◽  
...  
Keyword(s):  
Neutron Diffraction ◽  
Residual Stresses ◽  
Material Flow ◽  
Cold Drawing ◽  
Axisymmetric Deformation ◽  
Tube Length ◽  
Inhomogeneous Deformation ◽  
Drawing Process ◽  
Process Step ◽  
Residual Strains

Seamless tubes are used for many applications, e.g. in heating, transport gases and fluids, evaporators as well as medical use and as intermediate products for hydroforming and various mechanical applications, where the final dimensions normally are given by some cold drawing steps. The first process step – piercing of the billet, for example by extrusion or 3-roll-milling - typically results in ovality and eccentricity in the tube causing non-symmetric material flow during the cold drawing process, i.e. inhomogeneous deformation. Because of this non-axisymmetric deformation and of deviations over tube length caused by moving tools, this process step generates residual stresses. To understand the interconnections between the geometrical changes in the tubes and the residual stresses, the residual strains in a copper tube had been measured by neutron diffraction.

Rheology of neck formation in the cold drawing of polymeric fibers

1992 ◽  
Vol 45 (6) ◽  
pp. 997-1004 ◽  
Author(s):  
Bernard D. Coleman ◽  
Daniel C. Newman
Keyword(s):  
Cold Drawing ◽  
Neck Formation ◽  
Polymeric Fibers

scholarly journals Mechanical and Dielectric Properties of Aligned Electrospun Fibers

Fibers ◽  
2021 ◽  
Vol 9 (1) ◽  
pp. 4
Author(s):  
Blesson Isaac ◽  
Robert M. Taylor ◽  
Kenneth Reifsnider
Keyword(s):  
Dielectric Properties ◽  
Dielectric Property ◽  
Electrospun Nanofibers ◽  
Cold Drawing ◽  
General Interest ◽  
Electrospun Fibers ◽  
Energy Storage Devices ◽  
Electrospinning Technique ◽  
Specific Strength ◽  
Aligned Nanofibers

This review paper examines the current state-of-the-art in fabrication of aligned fibers via electrospinning techniques and the effects of these techniques on the mechanical and dielectric properties of electrospun fibers. Molecular orientation, system configuration to align fibers, and post-drawing treatment, like hot/cold drawing process, contribute to better specific strength and specific stiffness properties of nanofibers. The authors suggest that these improved, aligned nanofibers, when applied in composites, have better mechanical and dielectric properties for many structural and multifunctional applications, including advanced aerospace applications and energy storage devices. For these applications, most fiber alignment electrospinning research has focused on either mechanical property improvement or dielectric property improvement alone, but not both simultaneously. Relative to many other nanofiber formation techniques, the electrospinning technique exhibits superior nanofiber formation when considering cost and manufacturing complexity for many situations. Even though the dielectric property of pure nanofiber mat may not be of general interest, the analysis of the combined effect of mechanical and dielectric properties is relevant to the present analysis of improved and aligned nanofibers. A plethora of nanofibers, in particular, polyacrylonitrile (PAN) electrospun nanofibers, are discussed for their mechanical and dielectric properties. In addition, other types of electrospun nanofibers are explored for their mechanical and dielectric properties. An exploratory study by the author demonstrates the relationship between mechanical and dielectric properties for specimens obtained from a rotating mandrel horizontal setup.

Surface Spectroscopic Signatures of Mechanical Deformation in High-Density Polyethylene (HDPE)

2018 ◽  
Vol 72 (7) ◽  
pp. 1057-1068 ◽  
Author(s):  
Shawn C. Averett ◽  
Steven K. Stanley ◽  
Joshua J. Hanson ◽  
Stacey J. Smith ◽  
James E. Patterson
Keyword(s):  
High Density Polyethylene ◽  
Cold Drawing ◽  
Mechanical Deformation ◽  
Sum Frequency Generation ◽  
High Density ◽  
X Ray ◽  
Sum Frequency ◽  
Surface Normal ◽  
Methylene Groups ◽  
Spectroscopic Signatures

High-density polyethylene (HDPE) has been extensively studied, both as a model for semi-crystalline polymers and because of its own industrial utility. During cold drawing, crystalline regions of HDPE are known to break up and align with the direction of tensile load. Structural changes due to deformation should also manifest at the surface of the polymer, but until now, a detailed molecular understanding of how the surface responds to mechanical deformation has been lacking. This work establishes a precedent for using vibrational sum-frequency generation (VSFG) spectroscopy to investigate changes in the molecular-level structure of the surface of HDPE after cold drawing. X-ray diffraction (XRD) was used to confirm that the observed surface behavior corresponds to the expected bulk response. Before tensile loading, the VSFG spectra indicate that there is significant variability in the surface structure and tilt of the methylene groups away from the surface normal. After deformation, the VSFG spectroscopic signatures are notably different. These changes suggest that hydrocarbon chains at the surface of visibly necked HDPE are aligned with the direction of loading, while the associated methylene groups are oriented with the local C2 v symmetry axis roughly parallel to the surface normal. Small amounts of unaltered material are also found at the surface of necked HDPE, with the relative amount of unaltered material decreasing as the amount of deformation increases. Aspects of the nonresonant SFG response in the transition zone between necked and undeformed polymer provide additional insight into the deformation process and may provide the first indication of mechanical deformation. Nonlinear surface spectroscopy can thus be used as a noninvasive and nondestructive tool to probe the stress history of a HPDE sample in situations where X-ray techniques are not available or not applicable. Vibrational sum-frequency generation thus has great potential as a platform for material state awareness (MSA) and should be considered as part of a broader suite of tools for such applications.

Technology of the Contact Wire Manufacture for High-Speed Railways

2021 ◽  
Vol 410 ◽  
pp. 173-178
Author(s):  
Andrey V. Sulitsin ◽  
Raisa K. Mysik ◽  
Vadim V. Morgunov
Keyword(s):  
High Speed ◽  
Profile Analysis ◽  
Cold Drawing ◽  
Casting Process ◽  
Sediment Layer ◽  
Contact Wire ◽  
X Ray ◽  
Inner Surface ◽  
Full Profile ◽  
Continuously Cast

The article presents an overview of possible technological schemes to produce an overhead contact wire for railways. Pilot experiments were carried out on the manufacture of a contact wire made of CuMg0.3, CuMg0.4 and CuMg0.5 alloys and having a nominal cross section of 100 mm2. The contact wire was obtained from a continuously cast rod with small section, which was subjected to plastic deformation using the Conform technology and cold drawing of the extruded rod. In the casting process, we encountered the formation of cracks on the cast rod surface and the rods breakage. The inner surface of the graphite bushings of the mold after casting the rod was studied and a thin gray layer was found on the inner surface of the graphite bushings. Areas of the graphite bushing with gray layer were studied by scanning electron microscopy and element-by-element mapping was performed with the selection of a spectrum in the sediment layer area. In order to determine the phase composition of the sediment layer it was analyzed by the method of full-profile analysis of the X-ray diffraction pattern according to Rietveld. X-ray phase analysis showed the CuMg2 and Cu2Mg phases presence. This allowed us to assume a possible mechanism for the formation of the sediment layer. Ultimate tensile strength, elongation and electrical resistivity was determined. Analysis showed that the overhead wires made of CuMg0.3, CuMg0.4, CuMg0.5 alloys meets the requirements of GOST R 55647-2018 for wires made of the second conditional group bronze.

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