Subsequent Wire Drawing Research Articles

High performance Nb/TiNi nanocomposites produced by packaged accumulative roll bonding

Taking full advantage of intrinsic high strength of nano-reinforcements has been proven difficult in a composite until the concept of strain matching was experimental verified in a nanowire Nb/TiNi in-situ composite, which was obtained via solidifying eutectic Nb/TiNi and subsequent severe wire drawing. However, the volume fraction of the nano-reinforcement was dictated by eutectic reaction, which severely limited the development of high-performance composites. In this paper, the martensitic transformation nanocomposites were successfully acquired with increased volume fraction and changeable morphology of the nano-reinforcement through hot packaged ARB (PARB) and subsequent wire drawing. The nano-reinforcement with lamellar configuration in the composite could exhibit a large lattice strain of ~3.8%, which demonstrated the applicability and effectiveness of the strain matching principle in nano-lamellar composite. The obtained composites show a yield strength over 2.0 GPa and a quasi-linear elastic strain as larger as ~6.5% with adjustable apparent elastic modulus from 30 to 50 GPa.

A Technical Version of Achieving a Brass Coated Surface on Steel Wires

The paper presents in detail the technological flow for achieving, nowadays, for a brass coating on steel wires, as well as a proposed technological procedure (and patented by the patent 0011467) to get the same type of surface on the steel wires. It is noted that steel wires which have been finally brass coated are the constituent elements of motor vehicle tires, so the: "grip force" achieved by this coating and the rubber mass are particularly important.The current technological procedure for the construction of a brass coated surface on the steel wires involves a first phase of copper deposition (in fact in two steps: the first step consists in an electrodeposition followed by the second step: chemical deposition of copper). In the second phase the electrodeposition of Zn is achieved. Finally, the two previous depositions have been diffused (through a process called thermo-diffusion). The thermo-diffusion is achieved by direct electrical heating, but provides a product "with problems" for the subsequent wiredrawing process.We propose replacing it with a simpler technological procedure involving the achieving of the brass coating layer on steel wires through a single electrodeposition technique followed, by a final wiredrawing process [1].

Effect of Carbon on the Microstructure and Mechanical Properties in Wire Rods Used for the Manufacture of Cold Heading Quality Steels

Wire rod is an intermediate product, used in the manufacture of cold head quality steel. The quality of the wire rod in the as-hot-rolled condition, was evaluated in a series of carbon steels with and without boron content and at two different wire rod thicknesses. While the effect of boron on hardenability in the hardened and tempered condition is well studied, the effect of boron on the quality in the ferrite–pearlite condition is not well analysed. Hence the present study established that the addition of boron improved strength and ductility in carbon steels compared to steels without boron. The increased strength was attributed to the increased pearlite content and fineness of interlamellar spacing, and the strength was compared with Gladman’s equation and a theoretical equation. The room-temperature flow curve evaluation showed a higher strain hardening exponent in boron-containing steel compared to the steel without it. The upset ratio, which measured the ability of the wire rod for the subsequent wire drawing operation, was found to decrease with carbon content for steels without boron, while it was found to marginally increase in boron-containing steels. The evaluations were substantiated with microstructures evaluated in different grades and thicknesses.

EXTRUSION OF 01417 ALLOY INGOTS OBTAINED IN THE ELECTROMAGNETIC CRYSTALLIZER AT THE CONFORM UNIT

It is known that casting long ingots of small sections (∅8–12 mm) of 01417 alloy into an electromagnetic crystallizer makes it possible to obtain a dispersed structure with insignificant intradendritic segregation. Diffusion annealing of ingots (550 °C, 4–5 h holding time) eliminates intracrystalline segregation and reduces the level of internal stresses in metal thus providing the conditions for subsequent wire drawing. The paper demonstrates that high plastic deformation of ingots without diffusion annealing can be achieved by Conform continuous extrusion, which ensures high quality and geometrical accuracy of products. The analysis of various Conform units revealed an inherent weakness – the absence of connection between the system securing the fixed part of the detachable container (shoe) and the drive wheel shaft, which leads to an increased load in the operating mode. The purpose of the work was to upgrade the Conform unit by creating a connection between the shoe and the impeller shaft to obtain a high-quality billet for subsequent wire drawing of the ∅12 mm ingot cast into the electromagnetic crystallizer. An optimal temperature of ingot extrusion (300 °С) was found to eliminate the intense adhesion of wrought metal on the tool surface. The experimental ∅5 mm rod made of 01417 alloy obtained from the ∅12 mm ingot at the Conform unit features high processing ductility. This is indicated by an increase in its yield point and relative elongation. Metallographic studies demonstrated a fine-grained structure achieved in the extruded rod, which provides the conditions for subsequent wire drawing without annealing. The results of the study provide a basis for refining the process conditions of calibrated billet production on the Conform unit followed by wire drawing with required properties.

Conductive nanolamellar Cu/martensite wire with high strength

Cu wires can be significantly strengthened without losing much conductivity if a continuous nanolamellar structure with Cu and a strong second constituent is achieved. We report on a nanolamellar Cu/steel wire fabricated by repetitive hot-pressing, forging, rolling and subsequent wire drawing. Austenization and quenching in liquid nitrogen resulted in a Cu/martensite structure, exhibiting tensile strength of 1220 MPa. The electrical conductivity of the wire was measured to be about 60% International Annealed Copper Standard (IACS), which was comparable with Cu/Fe fabricated by alloying and casting. In situ tensile tests under high energy X-ray diffraction were utilized to explore the deformation behavior of the wire. It was found that the martensite carried about 60% of the load, accounting for the high strength.

INVESTIGATION OF INFLUENCE OF MORPHOLOGY OF PARTICLES OF GRADED WASTE CHIPS FROM BRASSES L63 ON PROPERTIES OF BARS AND WIRES, OBTAINING BY METAL FORMING

There was investigated influence of morphology of graded waste chips from brasses L63 on properties of bars and wires obtained by means of chipless shaping. For research particles of chips were divided on 3 types: spiral, flaked and sawing. Any one of them was heated to temperature 450±5 °С and briquetted on the forgemaster. Afterwards briquettes were heated to temperature of 850 °C and extruded by means of direct method with resulting of bars diameters 8 and 6 mm. Herewith elongating ratios were equal to 32 and 56, correspondingly. Pressed bars were subject to drawing, as consequence diameter of wire was equal to 2 and 3 mm. Examination of bars and wire properties showed that waste chips from brasses L 63 could be raw materials during manufacturing of half-prepared products for hot extrusion and subsequent wire drawing. There was established that morphology of chips particles has a little effect on fabrication characteristics of briquettes, as well as on mechanical characteristics of pressed bars and obtained by means of drawing wire, mechanical properties of which meet demands of GOST 1066-90.

INVESTIGATION OF GROW-BACK DURING ROLLING ON LONGITUDINAL V-SHAPE MILL

There was investigated influence of morphology of graded waste chips from brasses L63 on properties of bars and wires obtained by means of chipless shaping. For research particles of chips were divided on 3 types: spiral, flaked and sawing. Any one of them was heated to temperature 450±5 °С and briquetted on the forgemaster. Afterwards briquettes were heated to temperature of 850 °C and extruded by means of direct method with resulting of bars diameters 8 and 6 mm. Herewith elongating ratios were equal to 32 and 56, correspondingly. Pressed bars were subject to drawing, as consequence diameter of wire was equal to 2 and 3 mm. Examination of bars and wire properties showed that waste chips from brasses L 63 could be raw materials during manufacturing of half-prepared products for hot extrusion and subsequent wire drawing. There was established that morphology of chips particles has a little effect on fabrication characteristics of briquettes, as well as on mechanical characteristics of pressed bars and obtained by means of drawing wire, mechanical properties of which meet demands of GOST 1066-90.

Microstructure and mechanical properties of a cast and wire-drawn ternary Cu–Ag–Nb in situ composite

A ternary in situ metal matrix composite consisting of Cu, 8.2wt% Ag and 4wt% Nb was produced by inductive melting, casting, and subsequent wire drawing. The material was very ductile so that a maximum wire strain of η=10.5 was attained without intermediate annealing (η=ln(A0/A), where A is the wire cross-section). The wire has a very high strength (1840MPa at η=10.5) and at the same time good electrical conductivity (46% of the conductivity of pure Cu). The wire strength is much larger than predicted by the linear rule of mixtures. Up to wire strains of η≈8 the strength even exceeds that of Cu–20wt%Nb. The paper concentrates on the investigation of the evolution of the filament microstructure during wire drawing and its relation to the observed mechanical properties. The strength is discussed in terms of a Hall–Petch- or phase-barrier-type effect that arises from lattice dislocation pile-ups at the interfaces.

Factors affecting the upper critical field of Nb [sbnd]Ti wires

The intercomparison on the upper critical field measurement in the Nb wire(NST SRM 1457) has been performed through the VAMAS activity. The homogeneity in the Hc 2 of the wire was good enough, and the coefficient of scatter in the Hc 2 intercomparison was about 0.60 %. Effects of several factors on the HC of the Nb Ti wire are reported in the present paper. The coiled specimen shows slightly lower Hc 2 than the straight sample. The Hc 2 of the wire decreases by annealing, and recovers by wire drawing, The HC 2 of the wire shows an appreciable anisotropy with respect to the direction of applied field. The anisotropy in HC 2 is eliminated by annealing, and reintroduced by the subsequent wire drawing.

Scaleup of powder metallurgy processed Nb-Al multifilamentary wire

Powder metallurgy processed Nb-Al superconductIng wires were fabricated from billets up to 45 mm o.d. with nominal areal reduction ratios, R, up to 2 × 105, Nb powder sizes from 40 to 300 μm from various sources, Al powder sizes from 9 to 75 μm, Al concentrations from 3 to 25 wt % Al and with a wide range of heat treatments. All the compacts used tap density powder in a Cu tube and swaging and/or rod rolling and subsequent wire drawing. Both single strand and bundled wires were made. Overall critical current densities, J c , of 2 × 104A/cm2at 14 T and 104A/cm2at 16 T were achieved for 6 to 8 wt % Al in Nb.

High-remanence square-loop Fe-Ni and Fe-Mn magnetic alloys

This paper describes the magnetic properties of Fe-rich, Fe-Ni and Fe-Mn binary alloys processed to exhibit high remanence and square hysteresis loops. Recrystallization and decomposition of the cold worked alloys within the low temperature (α+γ) two-phase region lead to an extremely fine but essentially isotropic microstructure with an average particle dia. of 2000-4000 Å. A subsequent wire drawing results in an elongated and aligned fine-scale two-phase (α+α') structure with an average calculated particle diameter of several hundred angstroms and a length-to-dia, aspect ratio of 100-300. The Fe-Ni alloys exhibit much lower coercive forces compared with the Fe-Mn alloys, which is attributed to the smaller difference in magnetic saturation moment between the two decomposed phases in the Fe-Ni alloys. An Fe-8 wt% Mn alloy gives magnetic properties ( <tex xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">Br \sim 18000</tex> G, <tex xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">Br/Bs \sim 0.96</tex> , and <tex xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">Hc \sim 28</tex> Oe) comparable to or better than those of the high-cobalt Remendur or Nibcolloy alloys currently used in the remanent reed switches but contains no strategic element such as cobalt, and is very ductile for easy metallurgical processing. The Fe-Mn alloys with higher Mn contents exhibit a potential as permanent magnet alloys.

Superconducting properties and annealing behavior of filamentary Cu-based composites produced by powder metallurgy

Composite wires with discontinuous Nb filaments embedded in a Cu matrix are produced by hot extrusion of a powder mixture and subsequent wire drawing. Nb 3 Sn layers on the surface of the Nb filaments are formed by a diffusion treatment after plating with Sn. The peculiarities of the powdermetallurgical preparation technique and the origin of resistanceless currents in these materials are discussed. For Cu-Nb composites, it is shown that the critical currents are drastically enhanced by a final heat treatment, by which additional Nb precipitates in the Cu matrix.

Superconductivity in filamentary CuNb composites produced by powder metallurgy

Composite wires with discontinuous Nb filaments embedded in a Cu matrix are produced by hot extrusion of a powder mixture and subsequent wire drawing. The specimens exhibit superconductivity with critical current densities in zero field up to 4×104 A/cm2 at 4.2 K (after a reduction of the cross-section area of 5×104 by wire drawing). The origin of resistanceless currents in these materials with only 10 wt% Nb is due to superconducting bridges between the filaments which are formed by the proximity effect. The critical currents are drastically enhanced by a final heat treatment, by which additional Nb precipitates are produced in the Cu marix.

Structure and Magnetic Properties of Au–Co Aligned Eutectic

Directional solidification of Au–Co eutectic produces an aligned array of fcc cobalt rods in a gold matrix. The cobalt becomes finer, but more lamellar, as growth rate increases. Intrinsic coercive force increases with increasing growth rate, reaching 330 Oe at 2.1×10−1 cm/sec. Coercive forces up to 925 Oe are produced by subsequent wire drawing. Analysis of the magnetization curves indicates that deformation transforms the cobalt from fcc to hcp.