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Performance Improvement of the NiTi Alloy Wire Used for Aortic Stent―graft
ZHU Qing, YUAN Zhen-Yu, FENG Rui
无机材料学报 , 2011, DOI: 10.3724/sp.j.1077.2011.00979
Abstract: In order to improve the physical properties and biocompatibility of the aortic stent―graft, the effects of heat treatment and electrochemical polishing on nickel―titanium (NiTi) alloy wire during the stent―graft preparation were studied. It is found that heat treatment could help shaping the stent―graft and enhance the mechanical properties of the NiTi wire. The ideal heat―treatment process is heating at 480 and 510 for 7 min, respectively. By electrochemical polishing, the surface quality and fatigue life of the wire is highly improved. Meanwhile, electrochemical polishing results in reduction of the possibility of the mural thrombus formation and endothelial hyperplasy.
Sini?a Dunda,Trpimir Kujund?i?
Rudarsko-Geolo?ko-Naftni Zbornik , 2001,
Abstract: The efficiency of diamond wire saw upon ex plo i tation of natural stone depends on the right choice of the const ructional and technological fac tors of the machine, diamond wire and conditions, and way of explora tion in the particular kind of the rock. One of these parameters is the steel rope of diamond wire.A long-standing work on testing and certifying of hoisting ropes, experience and knowledge acquired upon these testings, aroused us to a detailed analysis and testing of the ropes which are used in diamond wire shaping. The paper presents the results of testings of steel ropes of diamond wire and the testings of rope joints i.e. tensile strength which can resist the joints between separate rope sections. The suggested idea regarding construction desings of steel rope of diamond wire, which is used in natural carbonate stone exploitation, is based on this experimen tal testing of steel ropes.
The influence of gelatine on the corrosion behaviour of cold worked copper wire in alkaline media  [PDF]
Ivanov Svetlana,Raj?i?-Vujasinovi? Mirjana,Stevi? Zoran
Journal of Mining and Metallurgy, Section B : Metallurgy , 2006, DOI: 10.2298/jmmb0601033i
Abstract: Copper wire obtained by dip-forming process was cold worked to the deformation degrees of 83, 87, 91, 95 and 99 %. Electrochemical potentiodynamic method was used to investigate corrosion behavior of these wires in aqueous solutions of Na2CO3 (1 mol/dm3). Open circuit potentials as well as peak potentials are given as a function of deformation degree in Na2CO3 without and with addition of gelatine in concentration between 0.1 and 0.5 g/l. It was found that the addition of gelatine does not change the mechanism of the process, but influences on current density. Small concentrations of gelatine (0.1 g/l or less) have positive influence on the corrosion protection of copper in alkaline solution, but the addition of gelatine in concentration 0.5 g/l causes the increasing of its corrosion rate.
The Effect of Annealing and Cold-drawing on the Super-elasticity of the Ni-Ti Shape Memory Alloy Wire  [cached]
Lei Xu,Rui Wang
Modern Applied Science , 2010, DOI: 10.5539/mas.v4n12p109
Abstract: Annealing combined with cold-drawing are the necessary method in the processing of Ni-Ti shape memory alloy thin wires. In this paper, the annealing temperature scan of 450~800?, time scan of 20min~3h and the cold-drawing amount of 6.9%~39% were chosen, and their effects on the thermo and mechanical performance of the Ni-50.5a.t.%Ti alloy wires have been studied. The DSC and tensile-recovery tests were adopted to obtain the phase transformation temperatures and mechanical hysteresis of the Ni-Ti SMA wires with different treatment conditions. The results show that the phase transition temperature of Ni-Ti wire can be changed by varying the annealing temperature and time; cold-drawing deformation and subsequent annealing have a great influence on the super-elasticity. Meanwhile, the surface oxide film and the flake cracks were obtained by SEM scanning. To obtain the best super-elasticity with the maximum cold working amount of 39%, the process with 39% cold drawing amount, 600 ? and 20 min annealing is shown to be effective.
Prediction of the Microstructural Variations of Cold-Worked Pure Aluminum during Annealing Process  [PDF]
Hamid Reza Rezaei Ashtiani, Peyman Karami
Modeling and Numerical Simulation of Material Science (MNSMS) , 2015, DOI: 10.4236/mnsms.2015.51001
Abstract: The mechanical properties such as hardness and ultimate tensile strength of metals depend on the grain size, which have to be properly controlled and optimized to ensure the better economy and desirable mechanical characteristics of the metals. In order to study the microstructure evolution of AA1070, many experimental tests were conducted at different cold working and annealing conditions. Utilizing the experimental results, the static recrystallization and grain growth behavior of AA1070 have been investigated and the developed equations that can be used to the FEM of the annealing process have been obtained. The agreement between numerical modeling and experimental results is reasonably good for this material. The results showed that the recrystallization and grain growth behavior of AA1070 was evidently affected by both the annealing temperature and plastic strain.
Remagnetization process of Fe-Rich Amorphous Wire under Time Dependent Tensile Stress  [PDF]
Przemys?aw Gawroński,Alexander Chizhik,Juan Mari Blanco,Julian Gonzalez
Physics , 2011,
Abstract: An influence of a time dependent external tensile stress on the remagnetization process of a bistable wire is investigated experimentally and numerically. The dependence of the magnetization on the frequency of the tensile stress is analyzed in terms of the magnetic domain structure of Fe-rich wires. The dependence of the switching field on the phase of the tensile stress is presented and reproduced by a straightforward numerical simulation of the remagnetization process in a bistable wire. There, the input is the experimental static dependences of the switching field and of the magnetization of the wire on an external tensile stress. The presented dependences of the switching field and the magnetization on the periodic tensile stress allow to tune the shape of the hysteresis loop, what can be useful in constructing a phase sensor.
The effect of electric spot-welding on the mechanical properties of different orthodontic wire alloys
Nascimento, Leonard Euler Andrade Gomes;Santos, Rogério Lacerda dos;Pithon, Matheus Melo;Araújo, M?nica Tirre de Souza;Nojima, Matilde Gon?alves;Nojima, Lincoln Issamu;
Materials Research , 2012, DOI: 10.1590/S1516-14392012005000049
Abstract: the aim of this study was to test the hypothesis that there is a direct relationship between surface structure and tensile strength of orthodontic alloys submitted to different levels of welding current. three types of alloys were assessed. one hundred and eight cross-sectional test specimens ("x") were made, 18 for each wire combination, and divided into 6 groups: ss (steel-steel); sn (steel-niti); sb (steel-beta-ti); nn (niti-niti); nb (niti-beta-ti) and bb (beta-ti-beta-ti), submitted to 6 spot-welding procedures at different levels of current (super micro ponto 3000). student-newman-keuls, wilcoxon signed-rank, and kruskal-wallis tests were used (p < .05). statistical difference was found between sn group and all the other alloy combinations (p < .05). initial roughness of alloys ranged from .04 to .55 ra, with statistical difference between groups (p < .001). the hypothesis was rejected and the tensile strength of ti-alloys combinations steel × beta-ti was significantly affected by the current level at p50, which changed the properties and structure of the wires.
Rolling, Partial and Full Annealing of 6061 Characterization of Microstructure, Tensile Strengths and Ductility  [PDF]
Wei Zhang
Materials Sciences and Applications (MSA) , 2016, DOI: 10.4236/msa.2016.79040
Abstract: The scope of this research is to compare the grain morphology and hardness of aluminum alloy 6061 samples in three conditions: fully rolled (full hard), partially annealed (half hard), and fully annealed (soft). It is found that cold rolling produced elongated grains, parallel to the rolling direction, and the highest degree of grain-elongation is found as a band in the center of the specimens. Shearing effects of cold rolling the buckled surface produced equiaxed grains near the rolling surfaces, and may have played a role in reducing the effect of string forming solutes near the said surfaces. Higher percent reduction performed in one stage of cold rolling produced a higher increase in tensile strength and a more significant decrease in ductility. Annealing produced the softest material.
Entangled single-wire NiTi material: a porous metal with tunable superelastic and shape memory properties  [PDF]
B. Gadot,O. Riu Martinez,S. Rolland du Roscoat,D. Bouvard,D. Rodney,L. Orgéas
Physics , 2015,
Abstract: NiTi porous materials with unprecedented superelasticity and shape memory were manufactured by self-entangling, compacting and heat treating NiTi wires. The versatile processing route used here allows to produce entanglements of either superelastic or ferroelastic wires with tunable mesostructures. Three dimensional (3D) X-ray microtomography shows that the entanglement mesostructure is homogeneous and isotropic. The thermomechanical compressive behavior of the entanglements was studied using optical measurements of the local strain field. At all relative densities investigated here ($\sim$ 25 - 40$\%$), entanglements with superelastic wires exhibit remarkable macroscale superelasticity, even after compressions up to 25$\%$, large damping capacity, discrete memory effect and weak strain-rate and temperature dependencies. Entanglements with ferroelastic wires resemble standard elastoplastic fibrous systems with pronounced residual strain after unloading. However, a full recovery is obtained by heating the samples, demonstrating a large shape memory effect at least up to 16% strain.
The Inspection of Spheroidized Annealing on SCM435 Cold-Forging Quality Steel Wires with Protective Atmosphere  [PDF]
Chih-Cheng Yang, Nan-Hua Lu
Materials Sciences and Applications (MSA) , 2019, DOI: 10.4236/msa.2019.1011048
Abstract: A cold-forging quality steel rod is usually applied for manufacturing wire which is generally produced by drawing wire coil into wire, followed by spheroidized annealing treatment to achieve the necessary formability for cold forging. The subcritical and intercritical processes are usually used to spheroidize the steel wires. The cold-forging quality SCM435 alloy medium carbon steel wires are widely used to manufacture high tension bolts for mechanical and heavy industry. In this study, the spheroidized annealing experiments on SCM435 alloy steel wires are conducted in a commercial bell furnace with a protective atmosphere of nitrogen or hydrogen. The mechanical properties of annealed steel wires are measured by tensile and Rockwell hardness tests and the process capability is evaluated. It is experimentally revealed that, for SCM435 alloy medium carbon steel wires, the wire quality with intercritical annealing is much better than that with subcritical annealing and is markedly affected by furnace atmospheres. The intercritical annealing quality on SCM435 alloy steel wire in hydrogen atmosphere furnace is better than in nitrogen atmosphere furnace. A comparison between the results obtained using the intercritical annealing with hydrogen atmosphere and the measures using the subcritical annealing shows that the intercritical annealing effectively improves the performance measures of low strength and high ductility over their values at the subcritical annealing. The results presented in this study could be a reference for fasters wire manufacturers.
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