Papers by Keyword: Plastic Deformation

Abstract: ince the temperature coefficient of resistance of Manganin (Cu-12Mn-2Ni) is extremely small, Manganin plate are used for resistors, especially shunts for current sensing.Generally, the melting and casting is used as a method to make an alloy such as Manganin. Further, the Manganin used as resistive material is produced by rolling after casting. Since such manufacturing processes have heating steps, long molding time is necessary and temperature control is important.In recent years, Cu-11Mn-4Ni powder has been developed. If manganin plate can be produced directly from alloy powder, simplification of the manufacturing process can be expected. A powder metallurgy is used as a method of solidifying and shaping the alloy powder. However many pores are generated in the sample because of using a binder. Therefore, the resistance value of the alloy fabricated through the method may not be stable.The Compression Shearing Method at Room Temperature (COSME-RT) is one of solutions to achieve the high density forming. In COSME-RT alloy powders are simultaneously loaded by a shearing force and a compressive stress in air at room temperature to form a plate. In the process, temperature control is unnecessary and the manufacturing time becomes shorter.In the present study, the fabrication of Cu-11Mn-4Ni plate is carried out by compression shearing method at room temperature and mechanical and electrical properties of the plate are evaluated.

Abstract: β titanium alloys, comprising alloying elements such as Nb, Ta, Zr, are considered promising materials for use in orthopedic applications, as the lower elastic modulus of these alloys, reduces the chance of implant failure caused by stress shielding. The mechanical behavior of these alloys depend on the composition as well as the stability of the phases. In the present study, the effect of cold rolling and subsequent annealing on the microstructure, texture and mechanical behavior of a Ti-Nb-Ta-O alloy has been investigated. Structural characterization was done using x-ray diffraction (XRD) and optical microscopy. Mechanical properties were evaluated by estimation of hardness and elastic modulus. The results show that, (1) the alloy contains single-phase β microstructure in both deformed as well as annealed condition with no evidence of deformation induced phase transformation, (2) the microstructures of cold worked alloy become increasingly inhomogeneous with dominance of shear bands at higher rolling strains, (3) high value of hardness to modulus ratio could be obtained in the present alloy due to stability of β phase and interstitial strengthening.

Abstract: Cemented carbides are the most common cutting tools for machining various grades of steels. In this study, wear behavior of two different cemented carbide grades with roughly the same fraction of binder phase and carbide phase but different grain size, in turning austenitic stainless steel is investigated. Wear tests were carried out against 316L stainless steel at 180 and 250 m/min cutting speeds.The worn surface of cutting tool is characterized using high resolution scanning electron microscopy (SEM), Energy dispersive X-ray spectroscopy (EDX), Auger electron spectroscopy (AES) and 3D optical profiler.The wear of cemented carbide in turning stainless steel is controlled by both chemical and mechanical wear. Plastic deformation, grain fracture and chemical wear is observed on flank and rake face of the cutting insert. In the case of fine-grained, the WC grains has higher surface contact with the adhered material which promotes higher chemical reaction and degradation of WC grains, so chemical wear resistance of the composites is larger when WC grains are larger. The hardness of cemented carbide increase linearly by decreasing grain size, therefore mechanical wear resistance of the composites is larger when WC grains are smaller.

Abstract: The paper presents an approach of non-destructive testing of plastic deformation of metals and alloys by measuring the differential thermoelectric power. Using the developed measuring device for this purpose, measurements of thermoelectric power were performed on several types of steels that are used in the manufacture of product pipelines. Incisions were made on the surface of the testes objects, for the purpose of experimental detection of the place of plastic deformation. In the process of stretching, thermoelectric power was measured at and near the place of the proposed plastic deformation. During the process of stretching the sample, the decrease in thermoelectric power measurement occurs almost linearly. The maximum change in the thermoelectric power measurement of the tested object was observe before the rapture discontinuity.

Abstract: The results of experimental study of laser welding alloys based on aluminum and titanium an intermediate composite Al+Ti insert obtained by explosion, using nanopowder additives and plastic deformation of the aluminum seam are presented. Morphologically high-quality welds have been obtained both in the welding of the aluminum plate and of the titanium one with the corresponding parts of the insert. It was found out that breakdown of the joint in the tensile test occurred along the aluminum part of the insert, which had a lower tensile strength than the titanium. The use of the nanomodifier without plastic deformation increases the strength of the weld joint by about 10% compared to the unmodified compound. The use of nanomodifying and strain hardening can significantly increase the tensile strength, the value of which is more than 97% of the strength of alloy (AA1135). The carried out experiments on laser butt welding of plates made of aluminum alloy 1424 systems Al-Mg-Li-Zr-Sc with their subsequent plastic deformation have confirmed the effectiveness of strain hardening of weld joints of aluminum alloys.

Abstract: The investigations of ultrasound Rayleigh wave parameters changing depending on localized plastic strain in AlCu4MgSi alloy and austenitic stainless steel AISI 304 are presented in this paper. Measurements of the ultrasound parameters and localized strain bands motion were carried out in-situ during the tensile tests of the specimens at the constant rate and room temperature. It has been found that the measurement of ultrasound velocity allows detecting the initiation of a localized strain band and its location relative to the acoustic measurement area independently of the deformation mechanism.

Abstract: Cyclic deformations of two ferritic, ductile cast irons, SiMo51 and SiMo1000, were studied in air and Ar using a new method, SRTC (stress relaxation with thermal cycling). Locked specimens were thermally cycled up to 800°C with isothermal holds, varying temperature interval, heating/cooling rates and hold times. A description of the mechanical response to thermal cycling of a locked specimen is given.

Abstract: The purpose of this paper is to present the microstructure and mechanical behavior of 6060 aluminum alloy after intense plastic deformation. Equal Channel Angular Pressing (ECAP) was used as a method of severe plastic deformation. Before ECAP part of the samples were heat treated to remove internal stresses in the commercially available aluminium alloy. The evolution of microstructure and tensile strength were tested after 1, 3, 6 and 9 ECAP passes in annealed and non annealed states. It was found that intensely plastically deformed refined grains were present in the tested samples and exhibited increased mechanical properties. Differences were noted between samples without and after heat treatment

Abstract: Binary Mg-Ca and ternary Mg-Ca-Zn alloys are a new group of magnesium materials, which can be used in many goods. Among others, biomedical applications of these alloys mainly involved surgical implants in the form of plates or screws. In order to improve mechanical properties and corrosion resistance of Mg-based alloys with Ca and Zn addition in as-cast state a plastic deformation was applied by using the KOBO extrusion method. The microstructure studies conducted by scanning microscopy show that the structure of the alloys after the plastic deformation exhibits banding character and the bands are oriented in the direction of an extrusion. A significant increase of mechanical properties was observed for MgCa5Zn1 alloy. After the plastic deformation, the corrosion potential determined for the MgCa5 and MgCa5Zn1 alloy is shifted into the positive direction, which may suggest the increase of corrosion resistance. Moreover, the MgCa5 alloy in as-cast state was completely dissolved after 288 h of immersion in Ringer’s solution. A volume of hydrogen evolution for the same alloy after plastic deformation showed a value of 35 ml/cm².

Abstract: The purpose of this paper is to determine the influence of temperature of plastic deformation on the structure and mechanical properties of copper alloys of the types CuCo1NiBe (CCNB), CuCo2Be (CB4), CuNi2SiCr (CNCS), CuNi1P (CNP) and CuCr1Zr (CW106C) applied on electrodesduring a tensile test. Tensile tests were carried out on polycrystalline samples of above mentioned alloys, which confirmed the presence of inhomogeneous plastic deformation in specified temperature ranges for each alloy. The tensile test of the investigated copper alloys were realized in the temperature range of 20÷800 °C with strain rate of 1.2•10^-3s^–1 on the universal testing machine. Metallographic observations of the structure were carried out on a light microscope and the fractographic investigation of fracture on an electron scanning microscope. Performed experimental studies have proven that analyzed structural factors, in a range of investigated strain conditions at elevated temperature, significantly influence the phenomenon of the Portevin Le Chatelier (PLC) type instability of plastic strain, revealed in low-alloy copper alloys. Moreover, it was found that the impact of examined factors on the PLC effect should be considered comprehensively, taking into account their synergic interactions.