Papers by Keyword: Microhardness

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Authors: Sherzod Kurbanbekov, Маzhyn Skakov, Michail Scheffler, Azret Naltaev
Abstract: In the present work the results of electrolytic-plasma treatment influence on the mechanical properties and structural-phase condition of steel’s 12Cr18Ni10Ti surface layers. In the work, the mechanical characteristics of steel’s surface layers are investigated, cemented in electrolytic plasma with the composition of 10 % Nа2CO3 and 10 % С3Н8О3. The operational parameters for the processing are determined. The optimal content of components in saturating mixtures of plasma by cementation is defined. According to the study it is found that, after electrolyte plasma processing, high wear resistance and hardness increased in 2-2.5 times more than in the original condition. The hardened layer with thickness 30-65 µm is formed. It is shown that after the electrolyte-plasma processing of steel 12Cr18Ni10Ti, microstructure contains particles of carbides and has a fine-grained martensitic structure.
Authors: Mazhyn Skakov, Lyaila Bayatanova, Michael Sheffler
Abstract: The research shows the results of electrolyte-plasma treatment influence on structure-phase state, mechanical properties and wear-resistance of drilling tool steel samples. The comparative analysis of microstructure, microhardness and wear-resistance of the samples in initial state and after electrolyte-plasma treatment is represented. It was found out that 18CrNi3MoA-Sh steel microstructure has fine-grained martensite-bainite structure after the treatment. It was determined that 18CrNi3MoA-Sh steel possesses high wear-resistance after electrolyte-plasma treatment, so that technology is characterized by low power consumption and cost price. The initial state microhardness is 2800 MPa on the average. Microhardness on the bearing lane surface after electrolyte-plasma processing is 7500 MPa on the average. Microhardness increases in 2-2.5 times more before treatment that indicates the technology efficiency.
Authors: Viktor Sergeev, Mark P. Kalashnikov, Vasilii V. Neufeld
Abstract: Results of surface modification of the VT-23 titanium alloy by high flux of copper ions with an energy of 2 keV and ion current density of 3.5 mA/cm2 was studied. The dependence of the microhardness and penetration depth of ion as function of duration of ion treatment was determined. Structural-phase state of ion-modified of the VT-23 titanium samples surface layer was investigated by TEM and SEM. Microhardness was researched by nanoindentation method.
Authors: Zdenek Joska, Jaromir Kadlec, Vojtěch Hruby, Zbynek Studeny, Tomas Binar
Abstract: The duplex treatment consisted of a plasma nitriding at 470 °C for 4 h and subsequent coating with TiN layer was applied on AISI 304L stainless steel. The article is concerned to a study of the chemical composition and mechanical properties of duplex system. GDOES method, laser confocal microscopy, nanohardness and indentation test were employed to characterize the chemical composition, depth profiles, surface morphology, hardness, adhesion. The results show that the duplex surface system possesses a desirable combination of properties especially hardness. Adhesion of PVD coating was increased on nitrided surface.
Authors: Tatiana Liptáková, Martin Lovíšek, Branislav Hadzima
Abstract: The Al-brasses are considered corrosion resistant construction materials often used to pipe systems in energy industry, where they are exposed to flowing liquids environments. In that system the brasses are loaded chemically and mechanically. The aim of our research work is to compare corrosion properties of four Al-brasses produced by different manufactures because in operation conditions they have dissimilar reliability and durability. The examined Al-brasses have similar chemical composition but differ in microstructure, surface state what affects their corrosion and mechanical properties. The effect of the mentioned parameters on corrosion and mechanical susceptibility to degradation are investigated by chosen experimental methods.
Authors: Stanislav Rafaelevich Abulkhanov, Dmitrii Leonidovich Skuratov, Aleksei Nicolaevich Shvetcov
Abstract: A traveling sphere by an elastic cylinder surface boundary problem is considered. At a contact zone the friction force and adhesive bond areas are supposed. The received solution enabled to estimate a plastic deformation area. The experimental and calculation data comparison found the acceptable accuracy of plastic deformation depth estimation. The devised methodology makes it possible to estimate the radius joining points depth of the plastic deformation by sphere.
Authors: Wan Mohd Hilmi Hussein Wan Omar, Nurulhuda Bashirom, Zuhailawati Hussain, Indra Putra Almanar, Wan Abdul Rahman Assyahid Wan Ibrahim
Abstract: This paper presents a study on the characterization of physical and electrical properties of Niobium Carbide (NbC) and Vanadium Carbide (VC) in Copper (Cu) matrix by mechanical alloying (MA) technique. The elemental powders of Cu, Niobium (Nb), Vanadium (V) and synthetic graphite powder were mechanically alloyed for 30 hours at 400 rpm in a planetary ball mill according to the stoichiometric ratio of Cu-(10-x) vol%NbC-(0+x) vol%VC (x=0,1,3,5,7,9) under Argon atmosphere. The as-milled powder were compacted at 400 MPa and sintered using microwave sintering furnace at 900°C with 1 hour soaking time. The phase identification was made by using the X-ray Diffraction (XRD) analysis. The microhardness, relative density and apparent porosity of sintered pellets were measured using Vickers microhardness and Archimedes principle, respectively. Electrical conductivity was measured using 2 point probe technique. Density of composite increase with increasing NbC content, while electrical conductivity also increase when NbC was added. Microhardness showed that single phase carbide has higher hardness value then multicarbide.
Authors: K. Chinnaraj, M. Sathya Prasad, C. Lakshmana Rao
Abstract: Chassis frame rails in a truck are load bearing structural members that integrate vehicle power train with superstructure to form a complete vehicle. Large numbers of bolt holes that are cut into these frame side members act as joineries and points of attachments for various sub systems of the truck. While bolt holes are unavoidable due to its primary functional importance, the near hole residual stresses remaining from hole cutting operations may play a significant role in deciding the life of frame rail sections as they lead to early initiation of fatigue cracks around bolt hole surface. In order to assess the extent of plastic deformation and resulting residual stress pattern in near hole areas of bolt holes, experimental investigation through microstructure analysis, micro-hardness and X-ray diffraction measurements has been taken up. The hole cutting operations considered for this exercise are drilling, punching, laser cutting and water jet cutting used to cut holes on truck frame rail sections. Apart from this, an assessment of shot-peened hole surface was also taken up to understand the effect of shot-peening on structural behavior of frame rail bolt hole sections. The experimentally measured near hole residual stress profiles can be considered as initial conditions for further numerical analysis to study the influence of bolt hole residual stresses on fatigue life of frame rail sections.
Authors: Ioan Catalin Mon, Mircea Horia Tierean, Eugen Cicala, Michel Pilloz, Iryna Tomashchuk, Pierre Sallamand
Abstract: This paper studies the ductile iron (DI) weldability using laser welding. For performing an Yb:YAG continuous laser was used, with a maximum power of 6 kW. The parametrical window power (P) - welding speed (S) was explored by carrying out the fusion lines on ductile iron plates without preheating, to determinate areas of weldability (complete penetration, correct geometry) to allow further characterization. The criteria for selection of focus areas were the geometry of the fusion lines and the absence of the welding defects. The unsatisfactory domains were characterized by: collapse of the melted metal, incomplete penetration, low fusion lines quality (geometry, compactness). In present study, several values of power and welding speed have been tested to identify their influence on geometry, compactness of the joints and mechanical properties. As result, the power-welding speed diagram for feasible domains of laser welding was generated.
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