Mechanical behaviors of quasi-ordered entangled aluminum alloy wire material

Quasi-ordered entangled aluminum alloy wire materials with nominal porosity of 57–77% have been fabricated by assembling a set of aluminum alloy wires with diameter of 0.28 mm. The as-prepared materials display three-stage stress–strain behavior under uniaxial compressive loading, i.e., initial nonlinear ‘quasi-elastic’ deformation, strain-hardening ‘pseudo-platform’ stage, and the final densifying stage. The experiment indicates that the structural deformation mechanism dominates the initial stress–strain behavior. At the elastic stage, the materials reveal a significant ‘strain-hysteresis effect’. The compressive yield strength and the elastic modulus exhibit a significant dependence of porosity, i.e., both decrease as the porosity increases. The data obey the typical power law relationship suggested by Gibson–Ashby.     

Mechanical behavior of entangled fibers and entangled cross-linked fibers during compression

Entangled fibrous materials have been manufactured from different fibers: metallic fibers, glass fibers, and carbon fibers. Specimens have been produced with and without cross-links between fibers. Cross-links have been achieved using epoxy spraying. The scope of this article is to analyze the mechanical behavior of these materials and to compare it with available models. The first part of this article deals with entangled fibrous materials without cross-link between fibers. Compression tests are detailed and test reproducibility is checked. In the second part, compression tests were performed on materials manufactured with cross-linked fibers. The specific mechanical behavior obtained is discussed.     

Impact behavior of different stainless steel weldments at low temperatures

A comparative study was made of the fracture behavior of austenitic and duplex stainless steel weldments at cryogenic temperatures by impact testing. The investigated materials were two austenitic (304L and 316L) and one duplex (2505) stainless steel weldments. Shielded metal arc welding (SMAW) and tungsten inert gas welding (TIG) were employed as joining techniques. Instrumented impact testing was performed between room and liquid nitrogen (?196 °C) test temperatures. The results showed a slight decrease in the impact energy of the 304L and 316L base metals with decreasing test temperature. However, their corresponding SMAW and TIG weld metals displayed much greater drop in their impact energy values. A remarkable decrease (higher than 95%) was observed for the duplex stainless steel base and weld metals impact energy with apparent ductile to brittle transition behavior. Examination of fracture surface of tested specimens revealed complete ductile fracture morphology for the austenitic base and weld metals characterized by wide and narrow deep and shallow dimples. On the contrary, the duplex stainless steel base and weld metals fracture surface displayed complete brittle fracture morphology with extended large and small stepped cleavage facets. The ductile and brittle fracture behavior of both austenitic and duplex stainless steels was supplemented by the instrumented load–time traces. The distinct variation in the behavior of the two stainless steel categories was discussed in light of the main parameters that control the deformation mechanisms of stainless steels at low temperatures; stacking fault energy, strain induced martensite transformation and delta ferrite phase deformation.     

Evolution of cementite morphology in pearlitic steel wire during wet wire drawing

The evolution of the cementite phase during wet wire drawing of a pearlitic steel wire has been followed as a function of strain. Particular attention has been given to a quantitative characterization of changes in the alignment and in the dimensions of the cementite phase. Scanning electron microscope observations show that cementite plates become increasingly aligned with the wire axis as the drawing strain is increased. Measurements in the transmission electron microscope show that the cementite deforms plastically during wire drawing , with the average thickness of the cementite plates decreasing from 19 nm (ε = 0) to 2 nm (ε = 3.7) in correspondence with the reduction in wire diameter. The deformation of the cementite is strongly related to plastic deformation in the ferrite, with coarse slip steps, shear bands and cracks in the cementite plates/particles observed parallel to either {110}_α or {112}_α slip plane traces in the ferrite.     

Investigation of service failures of steel music wire

An investigation of a number of service failures of the hard steel strings of plucked musical instruments is reported. All the failed strings were found to contain transverse fatigue cracks, mostly located near the end of the vibrating length (e.g. at the “bridge” of the instrument) and extending to about one third of the section thickness. One wire had corroded severely before failing in fatigue. Final failure occurred by ductile fracture.An analysis of the service stresses showed that the strings are subjected to high mean tensile stresses resulting principally from elastoplastic bending opposite the failure location. It is shown that a small cyclic axial tension arises from repeated plucking during playing and this can lead to fatigue initiation and propagation over a large proportion of the wire cross section.Neither surface nor bulk defects, wear nor contact stresses were found to be factors of importance in the cases examined, contrary to some speculation.     

Deformation textures in wire drawn perlitic steel

In this study, we followed the deformation microstructure and texture evolution during the cold wire drawing of a perlitic steel wire intended for civil engineering applications. The deformation level effect on the microstructure evolution and on the texture evolution is characterized. Wire drawing induces the lengthening of the perlitic grains along the drawing axis and leads to a strong hardness increase. X-ray texture measurements were performed. The reference state (initial wire) revealed an isotropic texture. The quantitative analysis show the development of the α fibre (<110>//ND (ND // wire) with the deformation. Moreover, the {001}?<?110?>?orientation (rotated Cube) is also present. The experimental techniques used in this study are the: Optical Microscopy (OM), the Electron Back Scattered Diffraction (EBSD), the X-ray diffraction, the Neutron diffraction and the Vickers microhardness.     

钢包铜复合线的制备研究

介绍了3种钢包铜复合导电柱的复合坯制备方法，探索了3种复合坯的制备工艺（1）液固相复合法；（2）直接装配法：（3）特殊装配法，对制备出的钢包铜复合导电柱复合界面组织致密性、界面结合状态及密封性能的影响。试验表明：前两种工艺制备的复合线材其结合面有局部结合不紧密，在界面未形成冶金结合状态，致使复合界面经氦检漏有漏气现象；第三种工艺制备的钢包铜复合线经气密性等综合性能试验，达到了使用要求。     

Characterisation of severely deformed austenitic stainless steel wire

Abstract

The microstructure of 8 μm diameter wire produced by the severe deformation of 316L austenitic stainless steel has been examined using TEM and X-ray diffraction. The deformation imparted amounts to a true strain of 6·3. Data from previous studies on strain induced transformation of this steel have been combined with new results to show that true strains >2 are required in order to observe mechanical stabilisation, i.e. the cessation of martensitic transformation when the martensite/austenite interfaces are unable to propagate through the dislocation debris created in the austenite.     

Microstructural evolution of copper clad steel bimetallic wire

We investigated the microstructure of two different bimetallic wires of Copper Clad Low Carbon Steel Wire (LCSW), which had a 1006 steel core, and Copper Clad High Carbon Steel Wire (HCSW), which had a 1055 steel core. The HCSW generally showed higher hardness than LCSW because of the pearlitic grain structure. A low temperature annealing at 720 °C to the drawn HCSW caused a significant reduction of hardness, which was as low as that of an annealed LCSW. In general, both LCSW and HCSW showed strong global textured features after drawing, with the steel having a strong 〈1 1 0〉 fiber texture and the copper having a 〈1 1 1 〉-〈1 1 2〉 deformation direction. At the interface, a grain size discrepancy at the steel-copper interface was observed. Post-drawing, the LCSW copper grains exhibited refined grain sizes near the interface and has been explained in terms of shear strain gradient. The HCSW did not exhibit this copper grain size distribution but did exhibit a coarsening of the steel grains near the interface after a subsequent 720 °C heat treatment. This is attributed to the large localized stress concentration at the perimeter of the steel region during the drawing process. The strain induced regions at the steel-copper interface have been simulated by finite element modeling. These grain size discrepancies caused the smooth variation in nanohardness across the interface.     

Processing of titanium-based human implant material using wire EDM

Machinability of human implant materials without causing any surface damage is a challenge on current research. The effect of heat-affected zone (HAZ), load experienced, and chemical reaction after implantation are the profound factors influencing on degradation of implant machined surface. An attempt is made to study the machinability of titanium-based human implant materials. While machining, the surface quality of the implant materials with reference to electrochemistry and metallurgical behavior of plasma energy produced are investigated in detail. Materials removal and its surface quality during plasma spark were measured as a response on machining process. The influence of pulse on/off time and the voltage varied during experimentation are evaluated using factorial design. Further, the machined samples are subjected to metallurgical characterization studies using microscopic (SEM) and spectroscopic (EDS) analysis. Increase in voltage has produced better surface finish and reduced recast layer. Contribution of pulse duration is less compared to voltage. Thus, the difficulty on machining human implants can be performed with wire electrical discharge machining process with high surface quality.     

Reverse ageing in hot-rolled high-carbon steel wire rod

Effects of ageing time on area reduction of hot-rolled high-carbon steel wire rods were studied. Tensile testing and X-ray study of as-rolled wire rods were carried out. Gleeble simulation and hydrogen content determination were also conducted. The results show that the reduction of area increases with ageing time at room temperature and the UTS remain unchanged which are contrary to normal ageing or strain ageing. In normal ageing, the ductility drops and the yield strength increases. In this study, the Gleeble simulation and X-ray data support that the transformation from pearlite to austenite is normal and there is no evidence of retained austenite or martensitic transformation in the steel. The hydrogen content drops as the time passes. The drop is rapid in first few days and this drop increases the ductility in rolled high-carbon wire rod. Hydrogen reduces the cohesive strength and the pressure generated due to transformation of atomic hydrogen-to-molecular state combines with tensile stress and causes cleavage or mixed type of fracture.     

Static strain aging in high carbon steel wire

Abstract

Static strain aging in steel of approximately eutectoid composition has been investigated using tensile testing and transmission electron microscopy for material in both low prestrain and drawn conditions. Two dominant modes of strain aging have been identified: (a) a low temperature mechanism dependent on interstitial solute diffusion and (b) a pseudo recovery mechanism which operates above 150°C. In the low temperature range, there exists a microstructure dependent transition temperature below which the kinetics of aging obeys a t^1/3 relationship and above which a rate exponent of approximately 1/2 is obtained. This has been attributed to a change from planar solute diffusion to dissolution of cementite as the rate limiting process.

MST/1067     

Pass schedule of wire drawing process to prevent delamination for high strength steel cord wire

The high-speed drawing of high carbon content steel wires is usually conducted at room temperature employing a number of passes or reductions through several dies. In the multipass drawing process, the temperature rise at each pass affects the mechanical properties of the final product (such as its bending and torsion properties, and its tensile strength). This temperature rise during deformation encourages delamination in the wire, which has a deleterious influence on the torsional properties and durability of the wire. In this study, we investigated the delamination of wires using torsion tests and evaluated the wire temperature during drawing. Our data shows that one of the main reasons for delamination was an excessive rise in wire temperature. Based on our experimental results, in order to prevent delamination due to an excessive rise in wire temperature, a new isothermal pass schedule that could control the wire temperature was designed. The pass redesign for the conventional high carbon (0.75 wt%C) steel cord wire drawing process with delamination was carried out by using the isothermal pass schedule to control the wire temperature. In order to verify the effectiveness of the proposed method, wire drawing and torsion test were conducted. From the results of experiments, it was possible to produce high carbon steel cord wire without delamination.     

Tailoring the synthesis of stainless steel wire mesh-supported ZnO

The aim of this work was to synthesise different nanostructures of zinc oxide supported on a stainless steel wire mesh, using hydrothermal processes in which several conditions were applied. The effect of the different synthesis parameters on the final properties of the samples (yield and geometrical dimensions) were analysed and discussed. The ZnO nanomaterials obtained exhibit a homogeneous distribution over the metallic wire mesh, with mass yields in the range of 3–30 wt.%, a prismatic morphology with a hexagonal cross-section, lengths between 700 nm and 6 μm and widths in the 70 nm–2.3 μm range. These nanomaterials are intended to be applied in photocatalytic reactions and as catalyst supports.     

柔性环形防护网顶破受力归一化分析

开展了6组环形钢丝网片单元顶破承载力试验,并基于LS-DYNA开展了非线性数值模拟,揭示了柔性环形网的顶破受力的三阶段工作特性。进一步考虑钢丝缠绕圈数、圆环直径、顶破端与环形网的面积比以及环形网长宽比等影响开展参数分析,据此提出了环形网片拉伸变形的解析计算方法,建立了顶破力-拉伸位移的相关性方程。研究结果表明:随着圆环缠绕圈数的增多,环形网的极限破断力线性增大,极限拉伸位移线性小幅减小;随着圆环直径的增加极限破断力指数型降低,极限拉伸位移线性增大;随着顶破端与网片的面积比的增大极限破断力和极限拉伸位移均幂函数持续减小,变化速率基本一致;随着环形网长宽比的增大,极限破断力和极限拉伸位移都呈幂函数减小,破断力的减小更为明显。研究成果可用于柔性防护系统环形网单元设计。