Academic literature on the topic 'Micro-hardness maps'
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Journal articles on the topic "Micro-hardness maps"
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Magazzeni, Christopher M., Hazel M. Gardner, Inigo Howe, Phillip Gopon, John C. Waite, David Rugg, David E. J. Armstrong, and Angus J. Wilkinson. "Nanoindentation in multi-modal map combinations: a correlative approach to local mechanical property assessment." Journal of Materials Research 36, no. 11 (January 4, 2021): 2235–50. http://dx.doi.org/10.1557/s43578-020-00035-y.
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Abstract A method is presented for the registration and correlation of property maps of materials, including data from nanoindentation hardness, Electron Back-Scattered Diffraction (EBSD), and Electron Micro-Probe Analysis (EPMA). This highly spatially resolved method allows for the study of micron-scale microstructural features, and has the capability to rapidly extract correlations between multiple features of interest from datasets containing thousands of data points. Two case studies are presented in commercially pure (CP) titanium: in the first instance, the effect of crystal anisotropy on measured hardness and, in the second instance, the effect of an oxygen diffusion layer on hardness. The independently collected property maps are registered using affine geometric transformations and are interpolated to allow for direct correlation. The results show strong agreement with trends observed in the literature, as well as providing a large dataset to facilitate future statistical analysis of microstructure-dependent mechanisms. Graphical abstract
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Allart, Marion, Alexandre Benoit, Pascal Paillard, Guillaume Rückert, and Myriam Chargy. "Metallurgical Study of Friction Stir Welded High Strength Steels for Shipbuilding." Materials Science Forum 783-786 (May 2014): 2798–803. http://dx.doi.org/10.4028/www.scientific.net/msf.783-786.2798.
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Friction Stir Welding (FSW) is one of the most recent welding processes, invented in 1991 by The Welding Institute. Recent developments, mainly using polycrystalline cubic boron nitride (PCBN) tools, broaden the range of use of FSW to harder materials, like steels. Our study focused on the assembly of high yield strength steels for naval applications by FSW, and its consequences on the metallurgical properties. The main objectivewas to analyze the metallurgical transformations occurring during welding. Welding tests were conducted on three steels: 80HLES, S690QL and DH36. For each welded sample, macrographs, micrographs and micro-hardness maps were performed to characterize the variation of microstructures through the weld.
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Poria, Suswagata, Goutam Sutradhar, and Prasanta Sahoo. "Abrasive wear behavior of Al-TiB2 and Al-TiB2-nano-graphite metal matrix composites." Proceedings of the Institution of Mechanical Engineers, Part L: Journal of Materials: Design and Applications 235, no. 5 (February 8, 2021): 1146–59. http://dx.doi.org/10.1177/1464420721991582.
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This paper deals with abrasive wear behavior of two different composite materials namely Al-TiB2 and Al-TiB2-nano-graphite. At the time of fabrication, ultrasonic vibration is used along with mechanical stirrer to obtain uniform dispersion of micro (TiB2) and nano (graphite) reinforcement phase. Uniform dispersion is confirmed through SEM images of cast composites. Micro-hardness values are obtained for composites and base alloy. Wear tests under two-body abrasion are performed by a tribological test apparatus where composite pins are being rubbed against a disc holding different grades of SiC abrasives: 240 grit, 320 grit and 400 grit. Operating load is varied between 10N and 30N while sliding speed and duration of sliding are kept fixed. Effects of load, reinforcing phase content and abrasive grit size on abrasive wear and friction behavior have been evaluated. Al-TiB2 composites demonstrate higher wear resistance and better friction behavior in comparison with base alloy under all operating conditions. Addition of nano-graphite phase contributes in achieving better abrasive wear and friction performance of Al-TiB2 composites. With increase in grit size, wear reduces for composites and base alloy while wear increases with load. Worn surfaces of samples and emery papers are studied using SEM micrographs and EDX maps. Wear debris at different operating conditions are studied also using SEM and EDX. Operative wear mechanisms are identified from the experimental results.
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Malcharcziková, Jitka, Miroslav Kursa, and Martin Pohludka. "Nickel Alloys in Directionally Solidified State – Characterisation of Microstructure and Phase Composition of the Alloys." Materials Science Forum 782 (April 2014): 441–44. http://dx.doi.org/10.4028/www.scientific.net/msf.782.441.
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The paper deals with the characterisation of the structure and phase composition of selected types of nickel alloys. Experimental alloys were prepared by vacuum induction casting. Castings were directionally solidified in corundum tubes with specified apex angle in the two-zone crystallisation furnace. Rate of directional solidification was 100 mm/h. Observation was carried out on the samples in the as-cast and directed state. Influencing of the structure by the process of directional solidification is evident. Porosity and micro-hardness were determined in transverse and longitudinal sections of individual samples and character of the formed structures was evaluated. Microstructural characterisation of materials was performed with use of scanning electron microscope. Distribution of individual elements was captured on X-ray maps, which documented significant chemical heterogeneity of investigated samples. Matrix composition corresponds approximately to the nominal composition of the alloys. The alloys contain moreover with variable content of primary and alloying elements. In the alloys with molybdenum and zirconium the phase enriched by these alloying elements were detected. On the other hand chromium is evenly dispersed in the basic matrix and it does not accumulate in the phases.
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Statnik, Eugene S., Semen D. Ignatyev, Andrey A. Stepashkin, Alexey I. Salimon, Dilyus Chukov, Sergey D. Kaloshkin, and Alexander M. Korsunsky. "The Analysis of Micro-Scale Deformation and Fracture of Carbonized Elastomer-Based Composites by In Situ SEM." Molecules 26, no. 3 (January 22, 2021): 587. http://dx.doi.org/10.3390/molecules26030587.
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Carbonized elastomer-based composites (CECs) possess a number of attractive features in terms of thermomechanical and electromechanical performance, durability in aggressive media and facile net-shape formability, but their relatively low ductility and strength limit their suitability for structural engineering applications. Prospective applications such as structural elements of micro-electro-mechanical systems MEMS can be envisaged since smaller principal dimensions reduce the susceptibility of components to residual stress accumulation during carbonization and to brittle fracture in general. We report the results of in situ in-SEM study of microdeformation and fracture behavior of CECs based on nitrile butadiene rubber (NBR) elastomeric matrices filled with carbon and silicon carbide. Nanostructured carbon composite materials were manufactured via compounding of elastomeric substance with carbon and SiC fillers using mixing rolling mill, vulcanization, and low-temperature carbonization. Double-edge notched tensile (DENT) specimens of vulcanized and carbonized elastomeric composites were subjected to in situ tensile testing in the chamber of the scanning electron microscope (SEM) Tescan Vega 3 using a Deben microtest 1 kN tensile stage. The series of acquired SEM images were analyzed by means of digital image correlation (DIC) using Ncorr open-source software to map the spatial distribution of strain. These maps were correlated with finite element modeling (FEM) simulations to refine the values of elastic moduli. Moreover, the elastic moduli were derived from unloading curve nanoindentation hardness measurements carried out using a NanoScan-4D tester and interpreted using the Oliver–Pharr method. Carbonization causes a significant increase of elastic moduli from 0.86 ± 0.07 GPa to 14.12 ± 1.20 GPa for the composite with graphite and carbon black fillers. Nanoindentation measurements yield somewhat lower values, namely, 0.25 ± 0.02 GPa and 9.83 ± 1.10 GPa before and after carbonization, respectively. The analysis of fractography images suggests that crack initiation, growth and propagation may occur both at the notch stress concentrator or relatively far from the notch. Possible causes of such response are discussed, namely, (1) residual stresses introduced by processing; (2) shape and size of fillers; and (3) the emanation and accumulation of gases in composites during carbonization.
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Schneider, Yanling, Reiner Zielke, Chensheng Xu, Muhammad Tayyab, Ulrich Weber, Siegfried Schmauder, and Wolfgang Tillmann. "Experimental Investigations of Micro-Meso Damage Evolution for a Co/WC-Type Tool Material with Application of Digital Image Correlation and Machine Learning." Materials 14, no. 13 (June 25, 2021): 3562. http://dx.doi.org/10.3390/ma14133562.
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Commercial Co/WC/diamond composites are hard metals and very useful as a kind of tool material, for which both ductile and quasi-brittle behaviors are possible. This work experimentally investigates their damage evolution dependence on microstructural features. The current study investigates a different type of Co/WC-type tool material which contains 90vol.% Co instead of the usual < 50vol.%. The studied composites showed quasi-brittle behavior. An in-house-designed testing machine realizes the in-situ micro-computed tomography (CT) under loading. This advanced equipment can record local damage in 3D during the loading. The digital image correlation technique delivers local displacement/strain maps in 2D and 3D based on tomographic images. As shown by nanoindentation tests, matrix regions near diamond particles do not possess higher hardness values than other regions. Since local positions with high stress are often coincident with those with high strain, diamonds, which aim to achieve composites with high hardnesses, contribute to the strength less than the WC phase. Samples that illustrated quasi-brittle behavior possess about 100–130 MPa higher tensile strengths than those with ductile behavior. Voids and their connections (forming mini/small cracks) dominant the detected damages, which means void initiation, growth, and coalescence should be the damage mechanisms. The void appears in the form of debonding. Still, it is uncovered that debonding between Co-diamonds plays a major role in provoking fatal fractures for composites with quasi-brittle behavior. An optimized microstructure should avoid diamond clusters and their local volume concentrations. To improve the time efficiency and the object-identification accuracy in CT image segmentation, machine learning (ML), U-Net in the convolutional neural network (deep learning), is applied. This method takes only about 40 min to segment more than 700 images, i.e., a great improvement of the time efficiency compared to the manual work and the accuracy maintained. The results mentioned above demonstrate knowledge about the strengthening and damage mechanisms for Co/WC/diamond composites with > 50vol.% Co. The material properties for such tool materials (> 50vol.% Co) is rarely published until now. Efforts made in the ML part contribute to the realization of autonomous processing procedures in big-data-driven science applied in materials science.
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Carsí, Manuel, José A. Jiménez, Xabier Gomez-Mitxelena, and Oscar A. Ruano. "Development of a 2.25%Cr Steel P23 Reinforced with Micro/Nano-Carbide Particles Produced by Self-Propagating High-Temperature Synthesis." Materials Science Forum 879 (November 2016): 1624–28. http://dx.doi.org/10.4028/www.scientific.net/msf.879.1624.
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In the present work, 1 wt.% of (Ti,Nb)C carbide particles prepared by self-propagating high temperature synthesis (SHS) were introduced into a melt of a conventional P23 steel to obtain a reinforced material with improved creep properties. The as-cast material showed a eutectic type microstucture, indicating partial dissolution of these carbides in the melt. Inside the dendritic regions, a bainitic/martensitic structure similar to that of the unreinforced material was present. A significant refinement of the prior austenitic grain size was revealed in the reinforced material. Brinell hardeness measurements reveal an increase of hardness in the reinforeced material due to the addition of the carbides. High strain rate compression tests were perfomed at temperatures in the range 950 and 1250oC to determine the optimum forming conditions. Stability maps for a wide range of temperatures and strain rates were drawn. The optimum temperature for the reinforced steel is about 77 K higher than for the non-reinforced steel.
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Kafiah, Feras, Jafar Al-Haidary, Sami Masadeh, Emad Abdelsalam, and Malek Alkasrawi. "A simple and economical method for the synthesis of steel-reinforced copper composite." Journal of Composite Materials, September 2, 2020, 002199832095639. http://dx.doi.org/10.1177/0021998320956390.
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The present study explores a new method of steel particle-reinforced copper matrix composite synthesis. Steel reinforced copper was prepared by stir casting processing method at variable percentages between 10 wt% and 50 wt%. Characterization and mechanical testing were performed on these composites using a variety of techniques. The results showed that the microstructure of the composites has a uniform distribution of steel particles in the matrix with good interfacial integrity. Brinell hardness, tensile and yield strengths, impact energy and compressive yield strength of the composites increased with increasing steel particle contents. Vickers micro-hardness increased markedly at the interface region between particle and matrix evident by the hardness maps. The friction coefficient increased proportionally with increasing steel particle content in the composite, but the contrary was noticed for accumulative wear amount. A slight decrease in deformability is expected by increasing particle content. A ductile fracture was noticed in fractographs of fracture surfaces. Cracks are propagated in the Cu matrix up to the point of fracture, i.e. not through the interfacial boundaries.
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Dickinson, Michelle E., and Adrian B. Mann. "Nanomechanics and Chemistry of Caries-Like Lesions in Dental Enamel." MRS Proceedings 844 (2004). http://dx.doi.org/10.1557/proc-844-y9.2.
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ABSTRACTDental enamel lesions are formed by the demineralisation of dental enamel due to dietary and bacterial factors which lower the local pH. If progression of this demineralisation continues the enamel structure eventually fails giving rise to a cavity (carie). Fortunately, in the earliest stages this process is reversible and if the pH of the environment increases, ions such as calcium, phosphate and fluoride can diffuse back into the enamel to give an arrested lesion. Hence, the tooth's structural integrity is preserved. The use of artificially produced enamel caries allows the study of lesion formation under conditions of highly controlled demineralisation. This provides a fundamental insight into the process of caries formation in enamel. In this study human premolars have been treated with a lactic acid solution to create artificial “caries-like” lesions in the enamel on the buccal side of the teeth. In the test samples the lesions penetrated around 100 μm into the enamel structure, accounting for approximately one tenth of the thickness of the enamel. Cross sections through the lesion were characterized with nanoindentation, electron probe micro-analysis and time of flight secondary ion mass spectrometry. From the data obtained maps of both mechanical and chemical properties were plotted across the entire width of the lesions. The results show that the lesions have a significantly reduced hardness and elastic modulus in comparison to sound enamel. These changes in mechanical properties were found to correlate with a loss of calcium and phosphate from the structure. There was also evidence of a stronger, less demineralised layer of enamel close to the lesion's surface. This surface zone is suggestive of remineralisation within the lesion which is of importance with regards to preventing the lesion developing into a carie.
Dissertations / Theses on the topic "Micro-hardness maps"
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Gunter, Cameron Cornelius. "Feasibility of Friction Stir Processing (FSP) as a Method of Healing Cracks in Irradiated 304L Stainless Steels." BYU ScholarsArchive, 2016. https://scholarsarchive.byu.edu/etd/6111.
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The current US fleet of nuclear reactors has been in service for three decades. Over this period, existing welds in stainless steel (SS) shrouds have sustained stress corrosion cracking (SCC) and are in need of repair. Additionally, helium has formed interstitially as a byproduct of proton bombardment. Current repair technology, such as TIG welding, puts extreme amounts of heat into the material and allows for interstitial helium atoms to aggregate and form bubbles/voids at grain boundaries. This significantly weakens the material, proving to be a very counterproductive and ineffective repair technique. Much study has been done on friction stir processing (FSP), but none has explored it as an enabling repair technology for use in nuclear applications. Because of its relatively low energy input as a solid state joining technology, it is proposed that FSP could effectively heal SCCs in these existing welds without the negative side effect of helium bubble formation. A spread of speeds and feeds were initially tested using a PCBN-W-Re tool on 304L SS. Six of these parameter sets were selected as representations of high, medium, and low temperature-per-power outputs for this research: 2 IPM-80 RPM, 2 IPM-150 RPM, 4 IPM-150 RPM, 4 IPM-250 RPM, 6 IPM-125 RPM, and 6 IPM-175 RPM. These varied parameter sets were tested for their tensile, micro-hardness, and corrosion resistant properties. In general, the lower IPM and RPM values resulted in higher ultimate tensile strengths (UTS). Higher IPM and RPM values resulted in tunnel, pin hole, and surface void defects. These defects caused premature failure in tensile tests and could often be identified through microscopy. Micro-hardness testing demonstrated a strong correlation per the Hall-Petch relationship – finer grain sizes resulted in higher yield strength (hardness values) of the material. The tool temperature during FSP was a good indicator of the expected hardness – lower temperatures resulted in higher hardness values. Corrosion testing was performed with a 1000-hour alternate immersion test in a room temperature 3.5% NaCl solution. With these testing parameters, the results demonstrated that FSP had no effect on the corrosion resistance of 304L SS under these conditions.
Conference papers on the topic "Micro-hardness maps"
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Gitis, Norm, Vishal Khosla, Ilja Hermann, and Michael Vinogradov. "Non-Destructive High-Resolution Stiffness Mapping of Composite Engineered Surfaces." In STLE/ASME 2008 International Joint Tribology Conference. ASMEDC, 2008. http://dx.doi.org/10.1115/ijtc2008-71178.
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Experimental evaluation of hardness, adhesion and Young’s modulus has been performed on polyimide polymeric coatings used in LCD displays and on composite polymer-based materials used in automobiles and aircraft. A novel Universal Nano+Micro Tester UNMT-1 with a nano-analyzer module NA-2 has been utilized. It measures scratch-hardness of coatings and thin films, utilizing the same nano-tip for both scratching and nano-imaging under the constant load. It measures scratch-adhesion with the same diamond tip for both scratching and nano-imaging under the continuously-increasing load. It evaluates homogeneity of films and composite materials by simultaneous Young’s modulus and topography nano-mapping, with a diamond nano-tip in a tapping mode, while frequency and phase of its vibrations are analyzed. The Young’s modulus maps allowed us to evaluate the distribution of SiO/Si02 particles embedded in araldite, with varying SiO/Si02 concentration. While the topography images could not distinguish between the particles and polymeric matrix, the nano-mechanical maps revealed the effects of particle concentration and agglomeration on the local modulus of the material and the relationship between the SiO/Si02 uniformity and uniformity in modulus. The nano-scratches of 60-nm polyimide coatings at progressively increasing and constant loads generated adhesion and scratch-hardness data, respectively. Within the applied loads of 20 to 100 μN, we observed and determined both the critical load, at which the coating was delaminated from the glass substrate, and a corresponding lateral delamination force. The mutually complimentary nano-images and force graphs coincided nicely.
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Gao, Huang, and Gary J. Cheng. "Laser Induced High-Strain-Rate Superplastic 3D Micro-Forming of Metallic Thin Film." In ASME 2009 International Manufacturing Science and Engineering Conference. ASMEDC, 2009. http://dx.doi.org/10.1115/msec2009-84087.
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Microforming of metals has always been a challenge because of the limited formability of metals at micro-scales. This paper investigates an innovative micro-forming technique: Laser Dynamic Forming (LDF), which induces 3-D superplastic forming in metal thin films. This forming process proceeds in a sequence of laser irradiation of ablative coating, ionization, shockwave generation and propagation in metal thin films, and conformation of metal thin films to the shape of micro/nanoscale molds. Because the deformation proceeds at ultrahigh strain rate, it is found that materials experience superplastic deformation at microscales. In this paper, experiments are carried out to understand the deformation characteristics of LDF. The shapes of the formed samples are characterized by scanning electron microscopy (SEM) and optical profilometer. The thickness variations are characterized by slicing the cross section using focused ion beam (FIB). The magnitude of deformation depth in LDF is determined primarily by three critical factors: thin film thickness, geometry of molds, and laser intensity. The relationships between laser intensity, film thickness, and mold size are explored in process maps to find out suitable processing conditions of LDF. Nanoindentation testings are conducted to show that the mechanical properties (hardness and yield strength) are increased significantly after LDF.
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Thodla, Ramgopal, Robin Gordon, and Feng Gui. "Effect of Reeling on Sulfide Stress Corrosion Cracking of Welded API5LX65 Line Pipe." In ASME 2015 34th International Conference on Ocean, Offshore and Arctic Engineering. American Society of Mechanical Engineers, 2015. http://dx.doi.org/10.1115/omae2015-42414.
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The effect of reeling on sulfide stress cracking (SSC) resistance of welded line pipe was investigated in two different environments, a modified NACE B environment and a fitness for service environment (pH = 5/pH2S = 0.46psia). Micro hardness maps were performed to characterize the welds both in the as fabricated condition as well as in the strained and aged condition. The hardness values in all of the conditions, was less than 250VHN (in compliance with NACE requirements). Triplicate specimens were tested in the as fabricated, strained and aged intrados and extrados in both the environments. SSC resistance in a severely sour environment (pH = 3.5/1psia H2S) was affected by reeling with cracking observed in both the intrados and extrados samples. No cracking was observed in the as-fabricated welds. However, in a moderately sour environment (pH = 5/0.46psia H2S) reeling did not have a detrimental effect on the SSC performance. No evidence of cracking on the as-fabricated, intrados, and extrados welds. In moderate sour service reeling doesn’t appear to have a detrimental effect on the SSC behavior.
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Akrivos, Vasileios, and Mike C. Smith. "Material Characterization on the Nickel-Based Alloy 600/82 NeT-TG6 Benchmark Weldments." In ASME 2019 Pressure Vessels & Piping Conference. American Society of Mechanical Engineers, 2019. http://dx.doi.org/10.1115/pvp2019-94017.
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Abstract The NeT-TG6 project examines the behaviour of a three-pass slot-welded benchmark made from Alloy 600 base material and Alloy 82 weld metal. This paper reports the material characterization studies conducted as part of the extensive round-robin activities performed to characterise the residual stress state in the TG6 benchmark using both measurement and simulation. An additional three slot specimen with one, two and three pass welds was manufactured to allow extensive characterization studies and comparison with the actual NeT-TG6 specimen, which contains only a single three-pass weld. Optical metallography and chemical composition studies examined the variability of the chemical composition and microstructure between parent material and weld metal with varying levels of dilution and differing thermo-mechanical behaviour. Micro indentation measurements were used to acquire hardness maps of the welded samples and reveal the impact of thermo-mechanical cyclic history. Electron microscopy and in particular electron back scattered diffraction (EBSD) was used to estimate the grain size variation, and, in the deformed parent and each weld bead, to assess the accumulation of plastic deformation.
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Caslaru, R., Y. B. Guo, and M. P. Sealy. "Fabrication and Characterization of Micro Dent Arrays by Laser Shock Peening on Ti-6Al-4V Surfaces." In ASME 2009 International Manufacturing Science and Engineering Conference. ASMEDC, 2009. http://dx.doi.org/10.1115/msec2009-84235.
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Surface micro dents may act as lubricant reservoirs to reduce friction and wear in sliding and rolling contact applications. Surface patterning has become a valuable technique for fabricating micro dents. Alternative methods such as micromachining present obvious limitations in comparison with laser shock peening (LSP). In this paper, the use of LSP along with an automatic X-Y table proves to be an attractive and reliable method for producing micro dent arrays with enhanced surface integrity and free of cracks. Surface topography, residual stress, and microhardness of the fabricated micro dent arrays on polished Ti-6A1-4V have been characterized. It has shown that LSP is capable of efficiently fabricating mass micro dent arrays with controllable size. The center area of the peened dents has highest hardness. In addition, high compressive residual stress can also be created.
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Takeuchi, Izumi, Takahiro Kushida, Shuji Okaguchi, Akio Yamamoto, and Mitsuru Miura. "Development of High Strength Line Pipe for Sour Service and Full Ring Evaluation in Sour Environment." In ASME 2004 23rd International Conference on Offshore Mechanics and Arctic Engineering. ASMEDC, 2004. http://dx.doi.org/10.1115/omae2004-51028.
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To establish mass production technology of high strength line pipe up to API-X70 grade for sour service, the HIC (Hydrogen Induced Cracking) phenomena in line pipe has been carefully examined. The micro-segregation zone originated at final solidification front, which has MnS inclusion and hard phase, was identified as the location of the initiation site of HIC. The proper procedures of Ca treatment to eliminate elongated MnS and TMCP application to reduce maximum hardness have proved to increase the HIC resistance in such segregation zone. In addition to the standard HIC test, full ring test under applied stress was conducted to assure the performance of high strength line pipe in sour service. The clean steel in mass production, which has enough HIC resistance, was attained for high strength line pipe up to API-X70.
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Santos, Genivaldo P., Shirley M. Pedreira, and Pedro T. Lacava. "Physical Property and Carbon Black Distribution Impact on Propulsion Efficiency of Paraffin-Based Fuel." In ASME 2012 International Mechanical Engineering Congress and Exposition. American Society of Mechanical Engineers, 2012. http://dx.doi.org/10.1115/imece2012-89201.
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In the last decade the hybrid propulsion has been considering as a viable alternative of chemical energy conversion stored in propellants into kinetic energy. This energy is applied in propulsive systems of manned platforms, maneuvering procedures and even in the repositioning process of micro satellites. It is a system of minimum environmental impact and lower cost than traditional systems based on liquid or solid propellants. Paraffin based grains are the hybrid solid fuels appointed as polymeric fuel substitute. The liquid layer formed on the burning surface ensures high regression rate when driven into the flame front. Paraffin grains allow row material recovery and reduce the risk of explosion in the presence of erosive burning. The structure of the grain and the control of the liquefying burning surface layer depend on the additives concentration, such as carbon black, which are added to the fuel matrix during the production process. In the solid propellant paraffin based grain a cylindrical center port developed during the centrifugation tends to concentrate carbon black in the outer region of the grain. During solidification 15% of shrinkage occurs and appears hardness gradient in the longitudinal and transverse directions. The influence of carbon black distribution and hardness gradient in paraffin based grain were evaluated in this work. The study suggests that multiple thin layers grain may generate burning surfaces with hardness and carbon black concentration almost constant. The ballistic properties and propulsion efficiency of a hybrid lab rocket scale with 150 N of thrust were evaluated in the pressure of 2.8 MPa with 140 Kg/(sm2) gaseous oxygen (GOX) mass flux, the results show up the nozzle operation and motor-propellant relationships.
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Tan, Jun, Tiantian Yu, Binshi Xu, and Bin Zhu. "Investigation of Microstructure and Properties of Ni/CNT Nanocrystalline Coating Deposited by Brush Plating." In 2007 First International Conference on Integration and Commercialization of Micro and Nanosystems. ASMEDC, 2007. http://dx.doi.org/10.1115/mnc2007-21202.
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Nickle-carbon nanotube (Ni/CNT) nanocrystalline coatings with different parameter were prepared by brush plating. The carbon nanotubes were added into common nickel solution for brush plating and ball milling was used to disperse the carbon nanotubes in the solusion. The concentration of carbon nanotubes in the solution was 3 g/l. The SEM and XRD were applied to investigate the grain size, microstructure and morphology of the coatings. The hardness and the wear mass loss of the coatings were examined on micro hardness tester and ball on disk tribotester. The results show that under a direct-current source, the grain size of the Ni/CNT coating was about 20 nm. Under a pulse-current source, the grain size of the Ni/CNT coatings decreased and the coatings gained smoother surface when the pulse-width became shorter. The grain size of the Ni/CNT coating increased with the heating temperature increasing and the average grain size of the coating heated at 500 degrees centigrade was over 50 nm. The microhardness of the Ni/CNT coating under a pulse-current source was higher than that of the coating under a direct-current source. Under a pulse-current source, the microhardness of the Ni/CNT coating increased when the pulse-width became shorter. The microhardness of the Ni/CNT coating changed slightly below 300 degrees centigrade, while decreased obviously after heated up to 400 degrees centigrade. The wear resistance of the Ni/CNT coating under a pulse-current was higher than that of the coating under a direct-current. Under a pulse-current, the wear resistance of the Ni/CNT coating increased when the pulse-width became shorter.
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Freis, D., P. D. Bottomley, J. P. Hiernaut, J. Y. Colle, J. Ejton, and W. de Weerd. "Post Irradiation Examination of HTR Fuel at ITU Karlruhe." In Fourth International Topical Meeting on High Temperature Reactor Technology. ASMEDC, 2008. http://dx.doi.org/10.1115/htr2008-58329.
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In the last years considerable efforts have been made at the Institute for Transuranium Elements (ITU) in order to reestablish European knowledge and ability in safety testing of irradiated high temperature reactor (HTR) Fuel Elements. In the framework of the 6th European framework programme a cold finger apparatus (Ku¨FA) furnace, formerly installed at FZ-Ju¨lich (FzJ), has been installed in a hot cell at ITU [Freis 2008] in order to test fission product release under high temperature and non-oxidising conditions. Several analytical methods (e.g. Gamma-spectrometry, mass-spectrometry) have been applied in order to analyse different isotopes released during Ku¨FA tests. After the heating tests, examinations of the fuel elements were performed including scanning electron microscopy (SEM) and micro-hardness testing of coated particles. Individual coated particles were object of heating tests in a Knudsen cell with a coupled mass spectrometer measuring all released species. In order to cover more accident scenarios, a second furnace for oxidising-conditions (air- or water-ingress) was constructed and installed in a cold lab. Furthermore a disintegration apparatus, based on anodic oxidation, was constructed and fuel elements were dissolved obtaining thousands of individual coated particles for further examination. A fully automated irradiated microsphere gamma analyzer (IMGA) is under construction and will be used, in particular, to identify and sort out failed particles.
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Nayak, Saurav K., Sanjay K. Mishra, Christ P. Paul, Arackal N. Jinoop, Sunil Yadav, and Kushvinder S. Bindra. "Effect of Laser Energy Density on Bulk Properties of SS 316L Structures Built by Laser Additive Manufacturing Using Powder Bed Fusion." In ASME 2019 Gas Turbine India Conference. American Society of Mechanical Engineers, 2019. http://dx.doi.org/10.1115/gtindia2019-2452.
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Abstract Laser Additive Manufacturing using Powder Bed Fusion (LAM-PBF) is one of the revolutionary technologies playing a key role in fourth industrial revolution for redefining manufacturing from mass production to mass customization. To upkeep the pace, Raja Ramanna Centre for Advanced Technology (RRCAT) has indigenously developed an LAM-PBF system and it is being used for process and component development for various engineering applications. This paper reports a parametric investigation to evaluate the influence of process parameters on the sample properties and to develop the process window for fabricating complex shaped engineering components. In the present work, an experimental investigation is carried out to investigate the effect of Laser Energy density (LED) on the porosity, microstructure and mechanical properties of SS 316L bulk structures fabricated by LAM-PBF system. LED is a combined parameter simultaneously considering the effect of Laser Power (P), Scan Speed (v), hatch spacing (h) and layer thickness (t). The effect of three LED values such as 83.33 J/mm3, 253.97 J/mm3 and 476.19 J/mm3 is investigated in the present work by building cuboidal samples at a layer thickness of 75 microns. Porosity is estimated using area fraction method in optical microscopy and it is found that the minimum porosity of 0.14 % and pore area of 1.28 mm2 are observed at 253.97 J/mm3. Maximum porosity of 18.85 % is observed at 83 J/mm3 due to incomplete fusion defects. However, porosity observed at 475 J/mm3 is 6.56 % with average pore size of 17.8 mm2. Microstructural studies show primarily columnar growth in all the samples with fine dendrites. The dendrite size is observed to be 3.2 μm, 2.4 μm and 1.46 μm at 83.33 J/mm3, 253.97 J/mm3 and 476.19 J/mm3 respectively. Micro-hardness and single cycle automatic ball indentation studies are found to be in agreement with dendritic size, with lower hardness at larger dendrite size. X-Ray Diffraction (XRD) studies indicate similar peaks at all the conditions, with slight peak shift observed with increase in LED primarily due to higher amount of residual stress. Thus, it can be inferred that LED of 253.97 J/mm3 is suitable for fabricating engineering components due to combination of lower porosity and fine dendritic structure.