Neuartige Faserverbunddrähte für die Leistungselektronik

Novel fibre reinforced wires for power electronics The use of power electronics within the scope of mechatronic applications as well as the increasing integration of components lead to increased requirements concerning their mechanical and thermal reliability. Today contact making in power electronics is mostly done by aluminum thick wire bonding. This process is highly productive, however the life time of power electronic components is meanwhile predominantly limited by the durability of these wire bonds. The thermal mismatch between the wire material and the connected components is one cause. A new starting point, in order to improve the reliability, is the application of new fibre reinforced metal matrix composite (MMC) wires with increased reliability under thermo‐mechanical stress. In the context of a research project MMC bond wires of different material combinations and arrangements were manufactured. Aluminum wires with copper fiber reinforcement as well as Copper wires containing FeNi36 fibre reinforcement have successfully be drawn to a final diameter of 300 μm. The fibre reinforcements should reduce the coefficient of thermal expansion and improve the mechanical strength. By aluminium copper MMC the electrical conductivity is increased as well. Measurements of the produced MMC wires confirmed these expectations. The manufacturing of the MMC took place on the basis of wire material of different diameters. These wires were stacked in capsules in different arrangements and material combinations. Subsequently, the capsules were either hot‐isostatically pressed or directly extruded. In such a way produced composites have been manufactured by rotary swaging and wire drawing into bond wires and after that tested.     

Hybridization of filler wire in multi-pass gas metal arc welding of SA516 Gr70 carbon steel

In the present investigation, multi-pass gas metal arc welding (GMAW) of SA516 Gr70 carbon steel was carried out by different filler wires such as solid, metal cored and flux cored, wherein, other process parameters were kept constant. The hybrid approach of multi-pass filler wires was applied to obtain three different welds. The root pass was filled by a solid wire for all three cases while the subsequent filler pass was applied through solid, flux-cored and metal cored filler wires, respectively. Metallographic, mechanical and metallurgical analyses such as macrograph study, optical microscopy, tensile testing and hardness variations were performed to address the quality of weld. The results revealed that defect-free sound welds were produced by the hybrid approach of different filler wires in multi-pass GMAW. Overall cost and time reduction can be achieved through hybrid filler welds, without affecting their mechanical strength. Angular distortion was reported minimum at hybrid weld of solid and metal cored filler wire. Maximum reinforcement with higher penetration was observed at weld of solid and metal cored filler wire. Impact toughness was reported higher in case of hybrid weld of solid and flux cored filler wire. Higher macro hardness was reported at weld of solid and flux cored filler wire.     

Fabrication and mechanical properties of steel–steel composites

Metal matrix composites based on a low carbon steel matrix reinforced with high carbon steel wires have been fabricated by a combined cold and hot rolling process. Both continuously and discontinuously aligned composites have been produced. A subsequent heat treatment allowed the formation of martenisitc, bainitic or pearlitic wires in a ferrite predominantly matrix. The optimum wire microstructure giving a composite with high strength and reasonable ductility was found to be bainitic — martensitic wires were found to contain microcracks that gave poor composite strengths and ductilities. The discontinuous wire composites produced similar strengths to the continuous composites only when they were deformed to give a wire aspect ratio greater than 20. The strengths of both types of composites showed a good fit to the rule of mixtures as the volume fraction of fibers was increased.     

Bending properties of hollow super-elastic Ti–Ni alloy wires and compound wires with other wires inserted

The purpose of this research was to investigate the possible orthodontic application of the hollow super-elastic Ti–Ni alloy wire, which was thought not only to deliver much lower and more continuous orthodontic force than conventional Ti–Ni wires, but also be able to be applied as a compound wire when combined with another wire. The examinations of bending properties were performed by the three-point bending test. The following results were obtained. 1. The hollow wire had lower load in the super-elastic range, smaller load-deflection rate and stress hysteresis in comparison with the conventional wire of the same diameter. 2. The load of the hollow wire was controllable by heat treatment. The stress hysteresis was further decreased by a two-step heat treatment. 3. The compound wire formed by inserting other types of wires into the hollow core exhibited changes in various bending properties such as increased load or load-deflection rate, according to the types and diameters of the inserted wire. The hollow wire delivers much lighter and more continuous orthodontic force, and, through heat treatment or deployment as a compound wire, it is possible to alter various bending properties. Therefore, this hollow wire was evaluated as a promising candidate for orthodontic application.     

INFLUENCE OF AXISYMMETRIC DEFORMATION PROCESSING METHODS ON THE MECHANICAL PROPERTIES OF Cu-Nb COMPOSITES

It has been shown that deformation processed Cu-19% Nb alloys with good strength and electrical conductivity can be developed in sizes that are useful for engineering applications. Mot extrusion of bundled sub-elemental Cu-19% Nb wires followed by cold drawing to make a composite wire of diameter equal to that of the initial sub-elemental wires resulted in a 67% increase in the ultimate tensile stress. However, on subsequent cold drawing of this composite wire the strength increased at a slower rate than that obtained on continuing cold drawing of the sub-elemental wire and the strength differential decreased. In addition, after cold drawing to equivalent diameters the electrical conductivity of the composite wire was less than that of the sub-elemental wire. These results indicate that while high strengths and good electrical conductivities can be produced in larger size deformation processed Cu-Nb composites by a process of bundling, extrusion and cold drawing of sub-elemental wires, there appears to be a limit to the amount of subsequent cold drawing feasible before the benefit in properties ceases.     

Influence of the die geometry on the hydrogen embrittlement susceptibility of cold drawn wires

Residual stress and strain states produced by wire drawing play an essential role in the main cause of failure of cold drawn wires: hydrogen embrittlement (HE), because of the influence of such fields on hydrogen diffusion within the material lattice. Therefore, variations on stress and strain fields, due to changes in the wire drawing process conditions, could modify the service life of these structural components. In this work the influence on HE of two parameters of the wire drawing process (the inlet die angle and the die bearing length) are analyzed by means of diverse numerical simulations by the finite element method (FEM). According to the obtained results, the effects of residual stress and strain fields produced by wire drawing on HE are less dangerous when the inlet die angle decreases or when the bearing length exceeds a characteristic value (wire radius), with a remarkable reduction of the driving forces for hydrogen diffusion. Consequently, wires drawn under such conditions (lower inlet die angle and longer bearing length) will exhibit a lower susceptibility to HE, thereby increasing their resistance to engineering failure.     

A parametric study on residual stresses and loads in drawing process with idle rolls

A comprehensive study of drawing process with flat idle rolls of round wires is presented through 3D mechanical finite element simulations. An elastic–plastic model is used for the wire material and contact behavior is simulated by a sliding–sticking friction model. The results of numerical simulations are compared with measurements on wires produced with a laboratory equipment. The comparison of drawing load and some geometrical characteristics of experimental samples with numerical model predictions allowed to establish a good correspondence of model with experimental findings, thus validating the numerical model. Residual stress of flat roll drawn wires, pressure distribution on the forming rolls and drawing load are studied. The effects of main process parameters such as initial workpiece diameter, forming rolls diameter and percentage of deformation are investigated. The results present a helpful insight into the process parameters effect in wire drawing with flat idle rolls thus furnishing the basic guidelines for process design and optimization.     

Festigkeitsabfall in Stahldrähten beim Feuerverzinken

Hot dip galvanizing induced strength decrease in wire steels Wire steels C80D and C80D Nb obtained by hot dip galvanizing procedure were investigated by optical and electron microscopy as well as by X‐ray analysis. The investigations were carried out at different stages of production of wires. The results of the investigations were checked by micro‐hardness measurements. Arising of cracks in wires surface during hot dip galvanizing as a reason for decrease in tensile strength was established. Influences of technological parameter such as galvanizing velocity, type of cooling and residual stresses and strength of wires before galvanizing on cracking of wire was taken in consideration.     

基于机器视觉的改进线束导线排序检测系统设计

目的 解决现有工业线束导线排序检测方法中存在的效率低、混色导线检测效果差等问题。方法 基于机器视觉技术设计一种线束导线排序检测装置,并结合图像处理技术和深度学习原理提出一种混色导线排序检测方法。首先根据线束图像中选择的感兴趣区域,分割出线束连接器图像和导线图像,并采用模板匹配和颜色定位方法完成连接器正反面的识别和单色导线的识别定位;然后采集并制作PE混色导线数据集,研究Faster R−CNN、SSD、YOLOv3和YOLOv5m等4种不同目标检测算法对PE混色导线的检测效果。结果 实验结果表明,YOLOv5m检测模型的检测速度和准确率兼顾性最好;改进系统后,检测时间减少了18.55%,平均识别准确率为98.83%。结论 改进后检测系统具有良好的检测效率和可靠性,适用于种类丰富的工业线束导线排序检测。     

Effects of temperature distribution on plasticity in laser dieless drawing

Temperature measurement based on grey body radiation spectrum is used to determine the temperature profile of hot wires in the deformation region in laser dieless wire drawing, with spatial resolution down to a few micrometers. The Voce parameters characterizing the high temperature plastic flow behavior of the wires are calculated using the temperature and diameter profiles of the wires in the deformation region. These parameters are determined for as-drawn and annealed pure nickel wires of 500 m diameter. Recrystallization and grain growth during the drawing process are studied. The effects of temperature, grain size and precursor wire diameter on wire drawability and strain rate are analyzed. The measured temperature and diameter profiles agree well with theoretical results. Grain growth increases rapidly with increasing temperature after recrystallization, and the grain size follows the thermal activation law. The effective activation energy increases for larger wire diameter. Surface morphology of the drawn wires and strain rate calculation show that dislocation motion is the dominant deformation mechanism.     

In situ observation of bamboo-shoot-like one-dimensional growth of SiOx–AgyO nanowires induced by electron beam irradiation

A one-dimensional growth induced by electron beam radiation has been in situ investigated by electron microscopy. Bamboo-shoot-like wires were grown under the proper electron beam irradiation condition from pre-prepared nanostructures of silver and silicon oxide particle balls. The growth kinetics of this kind of wire has been analyzed. The wires grew very fast in the beginning, but the growth rate decayed very quickly as the illuminating time increasing. The growth would be ceased in several seconds to several minutes. The diameter of the wire increased as the wire grew. A softening and deforming mechanism has been proposed to depict the growth of these new wires.     

The effect of metal wires on the fracture of a brittle-matrix composite

The behaviour of stainless steel, work-hardened nickel and annealed nickel wires bridging a crack in a brittle-matrix has been studied as a function of the length and orientation of the wire. The pull-out stress for stainless steel wire in epoxy resin increases less than linearly with wire length, following the behaviour predicted by Takaku and Arridge [6]. Wires inclined at 20° and 40° to the tensile axis gave pull-out stresses some 30% higher than wires parallel to the tensile axis, this increase being attributed mainly to enhanced friction on the bent wire near its point of exit from the matrix. Work-hardened nickel wires fractured when their length exceeded a critical value, and the critical length was significantly shorter for inclined wires than for wires parallel to the tensile axis. In contrast, annealed nickel wires, no matter how long, did not fracture but pulled out at a limiting stress which was slightly higher for inclined wires than for wires parallel to the tensile axis. The results show that, in some cases, there does not exist a critical length above which an embedded wire will fracture rather than pull out of the matrix.     

Comparison of the Properties of Cu-Nb/Ti Composite Wires Fabricated by Wire Drawing and Swaging

This paper presents a comparison of the mechanical properties and microstructure of heavily deformed Cu-Nb/Ti composite wires produced via different fabrication routes. Three main fabrication routes; wire drawing, swaging and a combination of swaging and drawing, were employed with/without intermediate annealing heat treatments. Metallographic and mechanical testing techniques were used to characterize the wires. The experimental results showed that the wire produced by drawing exhibited the highest strength. Also, the application of intermediate heat treatment during fabrication resulted in the reduction of tensile strength. It was found that the strengthening of this high volume fraction Cu-Nb/Ti composite could not be explained by standard Hall-Petch type model.     

Strength and Fracture Behavior of Ultrathin Pt Wires

Ultrathin metallic wires having defects may show much lower strength compared to the strength of the wire material. To characterize ultrathin Pt wires having the nominal diameter of 625 nm, tensile test of the wires was performed by developing a testing platform and a gripping technology. Fracture stress determined by the tensile test showed much higher value compared with that of bulk Pt. However, the fracture stress of some of the wires was lower than the yield stress of the wire determined by the bending test. From the observation of the fracture surfaces, it was found that the lower fracture stress of the wires was due to the defects in the wires and such wires showed brittle fracture behavior.     

Elektronenstrahl‐Randschichtbehandlung für die Herstellung verschleißbeständiger Auftragschichten auf nichtrostenden Stählen

Stainless steel components exposed to mechanical stresses are subjected not only to corrosion, but to abrasive wear. There are several possibilities for enhancing the wear resistance of stainless steels; however, such processes are very often associated with a reduction in corrosion resistance. This paper presents an electron beam surface treatment technology to significantly improve the wear resistance of austenitic steels (e.g. X6CrNiMoTi17‐12‐2) and duplex steels (e.g. X2CrNiMoN22‐5‐3), without a negative influence on the corrosion behavior. Fe‐ and Co‐additive wires were deposited thermally by electron beam cladding. The cladding layers produced were free of defects such as cracks and pores, and were well metallurgical bonded to the base materials. Microstructural analysis, hardness measurements, wear tests and corrosion tests were carried out. The wear rate k was reduced by a factor of 100 compared to the base materials for electron beam cladding with Fe‐based wire and by a factor of 10 with Co‐based wire. Corrosion resistance was preserved for the Fe‐based cladding layers and slightly increased (by a factor of 3) for the Co‐based cladding layers.     

Metallurgical Investigation of Failed Locked Coil Track Ropes Used in a Mining Conveyor

A locked coil track rope (LCTR) is essentially composed of wires (round and rail-shaped) laid helically in different layers. These wire ropes are sometimes used in conveyors carrying empty and loaded buckets in mining areas. During service, such wire ropes may fail prematurely due to disintegration/failure of individual groups of wires. To understand the genesis of LCTR wire failures, a detailed metallurgical investigation of failed rope wires was made and included visual examination, optical microscopy, scanning electron microscopy (SEM), and electron probe microanalysis (EPMA). Two types of failed wires were investigated; one is from a 40 mm diameter locked coil track rope and the other from a 53 mm locked coil track rope. Optical microscopy of failed round wires in the 53 mm diameter rope clearly revealed fully decarburized layers at the surface and a few grain-boundary cracks. From the location of the failure, it was clear that apart from static tensile loads, the wire ropes had been subjected to bending and unbending loads near the saddle, as fully loaded or empty buckets traveled access the conveyor. The SEM studies confirmed that the fracture had been caused by initiation of fatigue cracks in the decarburized zone under conditions of repeated bending and unbending stresses superimposed on the static tensile load.     

Deformation energy of NiTi shape memory wires

Deformation energy of NiTi wires with B2 and R phases was studied by the multiple tensile testing (MTT) method. In traditional materials, the total energy required to tear specimens is assumed to be the sum of elastic, uniform plastic, and post-uniform or tearing energy components. For the shape memory alloys, however, this classification is not valid due to their unusual superelastic/shape memory characteristics. Using a modified MTT method, different energy components were calculated by plotting different combination of deformation energies divided by the specimen cross-sectional area against the gage length of the specimens. The slope of the obtained straight line demonstrates the summation of the elastic, superelastic/shape memory, second elastic, and plastic energy per unit volume and its intercept gives the value of tearing energy. It was found that the uniform plastic energy per unit volume for the R-phase wires was considerably higher than that for the B2-phase wires. This caused a marked enhancement in the total deformation energy of the R-phase wire, as compared to the B2-phase wire. The effect of strain rate on the tensile behaviour and deformation energies of these materials was also investigated. Except the plateau stress of the tensile curve which was raised for both wires, the B2-phase wires were almost strain-rate-independent, whereas the R-phase wires were significantly influenced by the variation in strain rate.     

镍铝复合丝和镍铝合金丝及其涂层

介绍了镍铝复合丝和镍铝合金丝及其涂层的成分、相结构 ,比较分析了涂层的结合强度 ,分析了涂层自结合作用机理 ,估算了喷涂一平方米面积所消耗的丝材及相应用丝材成本 ,介绍了两种材料适用的对象及设备     

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.     

A practical in situ wire: a composite wire with many in situ processed Nb3Sn cores of an internal diffusion type

As a superconducting in situ wire for practical use, we propose a new type of composite wire with fine cores consisting of in situ processed wires of an internal diffusion type. These Nb₃Sn wires have merit in a simple fabrication process and a high stability compared with ordinary multifilamentary Nb₃Sn wires. Expected properties of the new type of Nb₃Sn wires were estimated based on a series of experimental results for a single in situ Nb₃Sn wire used as a fine core. A quantitative reliability of the new design estimation was examined by comparing the theoretical values with observed data on the electromagnetic properties of a test wire.