bluuebunny/crossref_metadata_2025 huggingface dataset:
Material Flow in Lap Joint of Dissimilar Metallic Foils by Friction Stir Diffusion Bonding with Micro Indentation
Authors: Kodama Takashi , Fukushige Hiroki , Igari Kouhei , Nakayama Kazuki , Takayama Yoshimasa
Published: December 2018

Friction stir diffusion bonding (FSDB) has been applied to lap dissimilar foils joints of aluminum alloy on top of commercial purity (CP) titanium. FSDB of the foils was successfully performed through stirring only the upper aluminum foil by the air spindle with an extremely-high rotation speed of 105,000 rpm. By using smooth surface of the tool tip, FSDB with micro indentation less than or equal 10μm could be carried out to improve the surface condition of the joint and the indentation depth required for joining was reduced. The material flow of the upper aluminum alloy foil in the FSDB was investigated by deposited platinum-palladium as the tracer material on the surface of the lower titanium foil. Then it was confirmed that the vestiges of vigorous stirring appeared in the region given at a distance from tool center while little vestiges was found in the other region. These regions seemed to be bounded by a radius of about 0.6 mm from the tool center. Moreover, the bonding strength distribution as a function of the distance from the tool center was likely correspondent to the stirring state.
Temperature Dependence of the Yield Stress in α-Titanium Investigated with Crystal Plasticity Analysis
Authors: Okuyama Yelm , Tanaka Masaki , Ohashi Tetsuya , Morikawa Tatsuya
Published: December 2018

The effect of the activated slip systems on the temperature dependence of yield stress was investigated in α-Ti by using crystal plasticity finite element method. A model for finite element analysis (FEA) was constructed based on experimental results. The displacement in FEA was applied up to the nominal strain of 4% which is the same strain as the experimental one. Stress-strain curves were obtained, which corresponds to experimental data taken every 50 K between 73 K and 673 K. The used material constants which are temperature dependent were elastic constants, and lattice friction stresses. The lattice friction stresses of basal slip systems were set to be higher than that of pyramidal slip systems at 73 K. Then, the lattice friction stresses were set to be closer as the temperature increases. It was found that the activation of slip systems is strong temperature dependent, and that the yield stress depends on the number of active slip systems.
Advanced Titanium Aluminides - How to Improve the Creep Resistance via Compositional and Microstructural Optimization
Authors: Mayer Svea , Kastenhuber Michael , Clemens Helmut
Published: December 2018

Intermetallic TiAl alloys based on the γ-TiAl phase are already used as engineering light-weight high-temperature materials in aircraft and automotive engines. Thereby, they partly substitute the twice as heavy Ni-base superalloys. Present applications are, for example, blades in the low-pressure turbine of advanced aero-engines, turbine wheels for turbocharger systems of car diesel engines as well as engine parts used in racing cars. All these applications require balanced mechanical properties, i.e. certain ductility at room temperature as well as defined creep strength at elevated temperatures. The first part of this paper reviews the alloy design strategy, which was used for the development of a β-solidifying γ-TiAl-based alloy, the so-called “TNM alloy”, which exhibits an excellent hot-deformability. In the meantime, the TNM alloy with the nominal composition of Ti-43.5Al-4Nb-1Mo-0.1B (in atomic percent, at.%) is introduced in a particular eco-friendly and fuel-saving aero-engine, which is powering a medium-range aircraft since the beginning of 2016. In the second part of this work the microstructural parameters are highlighted, which influence the failure strain at room temperature and creep strength at elevated temperatures. It will be shown how the creep resistance can be improved by tailoring phase fractions as well as the spatial arrangement of the microstructural constituents.
Strain Softening of Aluminum in Shear at Elevated Temperature
Authors: Kassner Michael E. , Ermagan Roya
Published: December 2018

Large-strain deformation of aluminum in shear consistently evinces strain softening of roughly 15-20%. Most researchers have suggested that this flow stress decrease is a consequence of a decrease in the average Taylor factor as a consequence of a shear-texture. The authors also consider, now, the possibility that changes in the dislocation climb stress induced by the texture could rationalize the softening. This work reports on an analysis of large strain deformation of aluminum single crystals in the softest orientation {111} <110>. Here softening is not observed. However, this result and other in earlier publications are consistent with dislocation climb being the rate-controlling process that also explains the observed stress versus strain behavior.
Micro-Scale Mechanical Behavior of Ultrafine-Grained Materials Processed by High-Pressure Torsion
Authors: Kawasaki Megumi , Han Jae Kyung , Lee Dong Hyung , Jang Jae Il , Langdon Terence G.
Published: December 2018

Bulk ultrafine-grained (UFG) materials usually show superior mechanical and physical properties. The development of micro-mechanical behavior is observed after significant changes in microstructure through high-pressure torsion (HPT) processing. This report summarizes recent results on the evolution of small-scale mechanical response examined by the nanoindentation technique on two UFG materials including a high-entropy alloy and an Al-Mg metal matrix nanocomposite processed by HPT. Special emphasis is placed on demonstrating the interrelationship of essential microstructural changes with increasing torsional strain and applying a post-deformation annealing treatment and the evolution of the micro-mechanical behavior in these UFG materials by estimating the strain rate sensitivity.
Cracking and Failure in a High Strength Low Alloy Steel during Solidification
Authors: Loucif Abdelhalim , Shahriari Davood , Chadha Kanwal , Zhang Chunping , Jahazi Mohammad , Tremblay Rami , Lapierre-Boire Louis Philippe
Published: December 2018

The present study focuses on characterizing cracks and fracture that appeared during solidification in the segregated zones of the as-cast structure of a large size ingot made of high strength low alloy steel. Solidification experiment was conducted, using Gleeble® 3800 thermo-mechanical simulator, on samples taken from the ingot/hot top interface of a 40 MT (Metric Ton) ingot. The thermal cycle consisted in heating from ambient temperature to 1385 °C with a constant heating rate of 2 °C/s followed by a free cooling. Optical and scanning electronic microscopies were used to analyze and quantify the cracked regions. Microstructural observations revealed that shrinkage during rapid solidification of melted grain boundaries ultimately led to the initiation and propagation of cracks.
Effects of Homogenization-Free on the Microstructures of an Al-Mg-Si-Cu Hot-Rolled Plate for Automotive Pannel
Authors: Tian Ni , Liu Qi Long , Zhao Zi Yan , Zhao Gang , Liu Kun
Published: December 2018

The microstructure of Al-1.01Mg-1.11Si-0.38Cu-0.69Mn aluminum alloy plate hot-rolled from homogenization and homogenization-free ingots were investigated by optical microscopy and scanning electron microscopy assisted with energy dispersive spectroscopy (SEM/EDS). The results showed that there are 3 main kinds of constituents such as Mg2Si, AlCuMgSi and AlFeMnSi in the as-cast Al-1.01Mg-1.11Si-0.38Cu-0.69Mn aluminum alloy ingot. After homogenization treated at 545°C for 24h, the black Mg2Si and the white bright AlCuMgSi particles in the ingot dissolved into matrix, but the grey AlFeMnSi phase partly dissolved, contracted into sphere and become coarse, many ultrafine dispersoids appear in the dendritic arms. The constituents in the plates hot-rolled from the homogenization and homogenization-free ingots are both distributed as broken chains along the rolling direction. However, compared with the particles configuration in the plate that hot-rolled from homogenization ingot, the particles in the plate that hot-rolled from the homogenization-free ingot are finer, more numerous and more homogenous, and with insufficient recrystallization when the plates are solution treated at 545°C for 2 h and then water quenched.
Traveling Waves Induced by Sweeping Flows on Solidification Interfaces
Authors: Pocheau Alain , Jiang Tania , Georgelin Marc
Published: December 2018

Solidification of alloys in a thermal gradient usually involves the generation of flows by thermal or thermosolutal convection. We experimentally study their effects on the dynamics of a solidification interface by inducing a controlled sweeping flow in a directional solidification device. Flow is induced in the sample from an external thermosiphon. Downstream inclination of microstructures and downstream sidebranch development are observed. However, the major outcome is the evidence of large scale travelling waves on the solidification interface. They are induced by the coupling between solidification and flow and yield repetitive striations of the solid phase. Two waves are observed and characterized.
Parameters Affecting Energy Absorption in Metal Foams
Authors: Costanza Girolamo , Tata Maria Elisa
Published: December 2018

Recent research findings on the mechanical behavior of metal foams are summarized in this work. Thanks to their properties in compressive tests, a wide range of foamed materials has been considered for energy-absorption applications such as Al, Fe, Ti, Ni and its alloys. The main parameters affecting energy absorption are focused and presented: cell size, relative density, strain rate, hybrid foam (Al-Cu, Al-Ni), base metal, and composites structures (Al-foam filled tube and sandwich). Metal foam response, impact resistance and failure are discussed in many configurations and test conditions. The results of finite elements modelling and its validation by means of mechanical tests are discussed too.
Effect of Gap between Steel Sheet and Electrode on Resistance Spot Welding
Authors: Matsui Sho , Wakabayashi Chisato , Kodama Shinji
Published: December 2018

If resistance spot welding (RSW) is conducted when there is a gap between a steel sheet and an unmovable electrode, the steel sheets are bended by a movable electrode, and the quality of RSW is influenced. Therefore, it is necessary to understand the effect of the gap on RSW. In this study, two high-tensile strength steel sheets were welded with the gap. In addition, cross-section observations and cross tension tests were conducted to verify the effect of the gap on weldability and joint strength. Consequently, two notable results were obtained. First, the observation indicated that deformation around the corona-bond was varied depending on the gap. Second, the cross tension tests showed that the gap decreased the joint strength even though the nugget was large enough. These result indicated that controlling the gap is important to ensure the quality of RSW.
The Influence of Powder Particle and Grain Size on Parts Manufacturing by Powder Bed Fusion
Authors: Ghiuta Ioana , Gatto Andrea , Bassoli Elena , Munteanu Sorin Ion , Bedo Tibor , Pop Mihai Alin , GABOR Camelia , Covei Maria , Cosnita Mihaela , Cristea Daniel , Varga Béla , Munteanu Daniel
Published: December 2018

Nanostructured powder materials, or powders with increased amorphous ratio, can potentially lead to increased productivity during powder bed fusion, due to the hypothesis that nanostructured raw materials can be layer-sintered with lower specific energy, and consequently lower processing times when compared to commercial powders. Sintering of such materials can potentially be done faster, as compared to conventional powders. In addition, using nanostructured powders, or powders with high amorphous content, or even nanometric (nanosized particles) powders, can result in higher density and hardness values of the sintered part, using the same process parameters. The main issue with nanosized particles is their loss of flowability, which could be overcome by controlling the particle shape during manufacturing. This work presents our results concerning the manufacturing and characterization of titanium alloy powders, with potential use in additive manufacturing. The powders were manufactured using severe plastic deformation by mechanical milling from commercially available powders, with various rotation speeds, ball diameters, and milling periods, in order to obtain micrometric particles, but with nanometric or high amorphous content structures. The powders were further analyzed in terms of morphology, structure, and chemical composition.
Microstructure and Properties of Cu-Cr-Zr-Ag Alloy
Authors: Peng Li Jun , Mi Xu Jun , Xie Hao Feng , Yu Yang , Huang Guo Jie , Yang Zhen , Feng Xue , Yin Xiang Qian
Published: December 2018

The Cr precipitation sequence in Cu-Cr-Zr-Ag alloy during the aging process at 450°C could be obtained by Transmission electron microscopy (TEM) and High-resolution transmission microscopy (HRTEM) in the study. The strengthening curve shows a unimodal type and the tensile strength trends to peak when the aged for 4h. The Cr phase transformation of Cu-Cr-Zr-Ag aged at 450°C is supersaturated solid sloution→G.P zones→fcc Cr phase→order fcc Cr phase→bcc Cr phase. The orientation relationship between bcc Cr precipitates and the matrix change from cube-on-cube to NW-OR.
Synthesis of Cu-Ni-Al Shape Memory Alloy by Powder Metallurgy
Authors: Elsayed Ayman , Ibrahim Rabab , Bahlol Mohamed , Dawood Osama
Published: December 2018

Synthesis of Cu-Ni-Al alloy has been realized by powder metallurgy. Mechanical alloying was used to produce shape memory alloy consisting of Cu, x Al, and 5wt, % Ni to study the effect of using the aluminum ratios of 12.5, 13, and 13.5 wt.% and sintering temperature on the transformation temperature. The process to obtain the alloy has included cold compaction at 600 MPa, Ar Gas sintering at 950 °C, die forging at 900 °C under the pressure of 500 MPa, and heat treatment at 850 °C followed by water quenching. The results have shown that the proposed synthesis route could be used to obtain the alloy with proper transformation and metallurgical properties.
Cladding of Stellite-6/WC Composites Coatings by Laser Metal Deposition
Authors: Kunimine Takahiro , Miyazaki Ryusei , Yamashita Yorihiro , Funada Yoshinori , Sato Yuji , Tsukamoto Masahiro
Published: December 2018

This study aims to investigate the microstructure and hardness of multi-layered Stellite-6/WC metal-matrix composites coatings on metallic substrates cladded by laser metal deposition (LMD) for improvement of wear and corrosion resistances. As coating materials, Stellite-6 and WC-12wt.%Co powders were selected. Powder mixtures having various mixing-ratios of Stellite-6 and WC-12wt.%Co were provided vertically on S45C substrates by controlling powder feeding rates of the two powder feeders, individually. Stellite-6/WC composites which consist of three layers with different compositions were cladded on the S45C substrates by laser melting. Cross-sectional microstructure observation was carried out by using an optical microscope (OM). Vickers microhardness tests were conducted to evaluate hardness of the cladding layers and substrates. The experimental results demonstrate that hard multi-layered Stellite-6/WC metal-matrix composites coatings were successfully cladded on the S45C substrates. Property gradients in the Stellite-6/WC composites could be made due to the position-dependent chemical composition and microstructure made by controlling powder feeding rates of an LMD system.
High Pressure Cryogenic Nitrogen Jet for Clean Coating Removal: Experimental Study of Polyamide Ablation
Authors: Hajji Yassine , Entemeyer Denis , Serri Jérôme , Yahiaoui Mustapha , Tazibt Abdel , Grosdidier Thierry
Published: December 2018

The potential of a recently developed technique that uses a clean supercritical High Pressure Cryogenic Nitrogen Jet (HPCryoN2Jet) for surface ablation and cleaning is depicted. In contrast to existent coating-removal techniques (chemical stripping, hydro-blast, water jet cleaning...), as nitrogen is naturally recycled in the air, this process has a high potential for surface treatment without any chemical and physical effluents or sewage disposal. The treatment consists in impacting the surface with a high pressure (up to 3500 bar) cryogenic nitrogen jet (down to-160°C). The pressurized cryogenic nitrogen exits from a nozzle - having generally a 0.2 to 0.5 mm diameter outlet - to form the high velocity (supersonic) nitrogen jet. In this contribution, the ability of the process to remove polymeric (PA) coatings is evaluated on different types of metallic substrates (Cu, Al, E24, 316L stainless steel). The mechanisms of chip formation have been visualized using a high speed camera. Coating failure is shown experimentally to occur downstream of the jet and the influence of the substrate thermal properties on the stripping efficiency of the PA coating is highlighted.
Study and Development of a Multilayered Coating to Improve Hard Metal Cutting Tools Performances
Authors: Gobber Federico Simone , Rosso Mario
Published: December 2018

The use of coated hard metal is spread in all fields of mechanical working, both forming and machining. Different hard metals are used based on their mechanical characteristic that strongly depends on composition and grain size. Substrates such as HSS and WC – Co are typically coated with PVD thin layers in applications such as metalworking and cutting; thus lot of efforts are put in researching this specific field. Coating composition, and coating architecture are paramount topics in the subsject of surface anti – wear thin films. The focus of this study is to analyze the difference between two AlTiN coatings, a monolayer and a multilayer with gradient composition, from the point of view of microstructure and adhesion. Experimental cutting tests were done to characterize the behavior of the coating in face milling of AISI 660 heat resistant alloy: varying cutting speeds from 15 to 40 m/min it was finally assessed that a multilayer coating can give higher tool life with respect to a monolayer coating of the same composition.
Novel Methodology for the Selection, Dosing and On-Line Control of Corrosion Inhibitors for Industrial Acid Pickling
Authors: de Sanctis Massimo , Lovicu Gianfranco , Ishak Randa , Richetta Maria , Varone Alessandra
Published: December 2018

A novel methodology based on electrochemical hydrogen permeation tests is proposed to study the efficiency of commercial inhibitors for industrial acid pickling of iron and mild steels. Weight loss measurements and hydrogen permeation tests have been carried out in order to compare the sensitivity of different techniques to variations of low inhibitor dosages. It has been found a close dependence between low amounts of filming inhibitors and hydrogen uptake in the metallic surface with related permeation currents. The high sensitivity of permeation currents may be very useful to establish and also control the optimum amount of active substances in industrial pickling baths, with related cost savings. The implementation of the proposed methodology to improve the control of industrial pickling plants is also envisaged, since it would be possible to improve both sensitivity and time response of experimental permeation curves.
Novel Hot-Rolled Structural Plate Steels with Yield Strength of 700 Mpa and Excellent Usability
Authors: Ritola Ville , Pyykkönen Juha , Martin David , Suikkanen Pasi , Carlsson Magnus
Published: December 2018

Hot rolled structural plate steels with yield strength of 700 MPa are an excellent choice for a variety of demanding applications that require excellent toughness and welding properties. SSAB has developed novel hot-rolled plate steels that are produced using precision controlled rolling and an innovative cooling and tempering strategy that ensures invariable mechanical properties in the width and the length directions of the plate. The recently developed steel meets or exceeds the requirements of EN 10025-6 for the S690QL grade. The minimum yield strength (ReH) is between 630 MPa and 690 MPa depending on plate the thickness, and the interval of tensile strength is 760 - 940 MPa, while the minimum elongation at fracture is 14 %. Further, an impact energy of 69 J at-40 °C on transverse V-notch specimen is guaranteed. The novel grades represent superior bendability and surface quality, weldability with excellent HAZ strength and toughness with very low CET and CEV values, exceptional consistency of properties within a plate guaranteed by close tolerances. In addition to the excellent formability, the novel hot rolled steels exhibit greatly improved toughness properties which provides for good resistance to fracture. These outstanding properties are achieved through carefully controlled manufacturing processes. In the present study, a sophisticated recrystallization based hot rolling process optimization method is presented. With the final aim to improve the impact toughness of the novel steel, recrystallization analyses and modelling of austenite grain size development through the rolling pass schedule is performed.
The Effect of Flue Gas Environment on the Corrosion Behavior of the Sulfuric Acid Dew-Point Corrosion Resistant Steel
Authors: Lee Byoung Ho , Jo Min Ho , Yoo Yun Ha
Published: December 2018

In order to compare the corrosion resistance of conventional low carbon steel, Cu containing low carbon steel for sulfuric acid dew-point corrosion inhibition, and stainless 409L, immersion tests were carried out in 50 wt.% sulfuric acid. The effects of HCl concentraion on the corrosion behavior in a fixed sulfuric acid concentration (16.9 vol.%) was also investigated by immersion test. In addition to immersion test, field test in a thermal plant was carried out for 10 months. As a result, it was confirmed that Cu-containing dew-point corrosion resistent steel has the highest corrosion resistance compared with other materials. To verify superior corrosion resistence of dew-point corrosion resistant steel, surface morpology after various test was observed by SEM. It was found that surface corroded product of the dew-point corrosion resistant steel was much denser and thicker compared with the other steel.
Influence of Rolling Force on Corrosion Resistance of Interstitial-Free Auto Sheet Steel
Authors: Fang Bai You , Yu Yang , Lu Lin
Published: December 2018

A three dimensional (3D) surface profiler, an X-ray residue stress tester, a potentiodynamic polarization approach and a damp heat test were employed to investigate the relationship between the rolling force (RF) and the corrosion resistance of interstitial-free (IF) auto sheet steels. The results show that the change of rolling force induces the variance of the surface topography and surface residue stress of IF steel. With the increasing RF, the corrosion resistance of IF steel in damp heat test can be enhanced, and the corresponding corrosion current density declines. Further, it is proved that the tensile stress on the surface can accelerate the corrosion rate of IF steel. As the compressive stress and the valley proportion on the surface increase, IF steel samples present a better corrosion resistance, because the compressive stress could retard the diffusion of corrosion media and the valley position possesses a lower electrochemical activity.
Electrochemical-Based Characterization of the Corrosion Fatigue Behavior of Creep-Resistant Magnesium Alloys DieMag422 and AE42
Authors: Klein Martin , Walther Frank
Published: December 2018

The corrosion fatigue behaviors of the creep-resistant magnesium alloys DieMag422 and AE42 were characterized by means of constant amplitude tests in sodium chloride solutions using corrosion potential and strain measurements. Characteristic microstructural deterioration and cracking processes in low and high cycle fatigue regime could be monitored on the basis of characteristic corrosion potential responses, which were investigated in detail by means of combined analysis of corrosion potential and total strain oscillations.
Hot Corrosion of Alloy 617 OCC in Simulated USC Power Plant Environment
Authors: Arivazhagan N. , Hari P.R. , Muktinutalapati Nageswara Rao , Pavan A.H.V.
Published: December 2018

Alloy 617 OCC, a variant of INCONEL 617 with optimised chemical composition, has been produced in India for manufacture of superheater and reheater tubing in boilers operating in advanced ultrasupercritical (A-USC) power plants. The tubing encounters intense hot corrosion conditions during service. The present study deals with hot corrosion behaviour of 617 OCC in A-USC environment. The environment occurring in A-USC plants was simulated in the laboratory by exposing the material coated with a mixture of salts at 700°C in a flowing gas mixture. For use in A-USC boiler technology, the metal loss due to fireside corrosion of the material should be less than 2 mm in 200,000 hours. The loss obtained in the present study was nearly 5 times this value. The corrosion processes were studied using SEM/EDAX, XRD and thermogravimetry. The degradation mechanisms coming into play, disqualifying the material for use in A-USC plants, would be discussed.
Deformation Structures in a Duplex Stainless Steel
Authors: Yvell Karin , Engberg Göran
Published: December 2018

The evolution of the deformation structure with strain has been studied using electron backscatter diffraction (EBSD). Samples from interrupted uniaxial tensile tests and from a cyclic tension/compression test were investigated. The evolution of low angle boundaries (LABs) was studied using boundary maps and by measuring the LAB density. From calculations of local misorientations, smaller orientation changes in the substructure can be illustrated. The different orientations developed with strain within a grain, due to operation of different slip systems in different parts of the grain, were studied using a misorientation profile showing substantial orientation changes after a true strain of 0.24. The texture evolution with increasing strain was followed by using inverse pole figures (IPFs). The observed substructure development in the ferritic and austenitic phases could be successfully correlated with the stress-strain curve from a tensile test. LABs were first observed in the different phases when the strain hardening rate changed in appearance indicating that cross slip started to operate as a significant dislocation recovery mechanism. The evolution of the deformation structure is concluded to occur in a similar manner in the austenitic and ferritic phases but with different texture evolution for the two phases.
Microstructure and Corrosion Behavior of Extruded Mg-Zn-Er Alloys
Authors: Bhat Panemangalore Devadas , Shabadi Rajashekhara , Gupta Manoj , Ambat Rajan , Ji Gang , Addad Ahmed , Lesven Ludovic
Published: December 2018

The current medical technology necessitates the usage of biodegradable metals like Magnesium (Mg) as the future implant material due to the numerous benefits it can provide. Therefore, new Magnesium-based rare earth alloys targeting biomedical applications were synthesized using Disintegrated Melt Deposition (DMD) technique followed by hot-extrusion. In this investigation, Zinc (Zn) and Erbium (Er) were chosen as alloying elements to provide suitable strengthening effect and Mg-2Zn, Mg-2Zn-2Er alloys were synthesized. With the addition of alloying elements, the grain size was reduced and several MgZn intermetallics were formed. Corrosion studies of as-extruded materials were done in 0.5 wt.% NaCl solution to elucidate the microstructure-corrosion relationship. Improved corrosion resistance is seen in the alloys in comparison to pure Magnesium. Addition of Erbium is seen to improve the protectiveness of the surface film formed during immersion. Both these elements have proven to increase the corrosion potential of Mg in NaCl solution.
Improvement of the Surface Properties of Low Temperature Plasma Nitrocarburized Martensitic Precipitation-Hardening Stainless Steel by Aging Treatment
Authors: Lee Insup
Published: December 2018

Various aging treatments were conducted on AISI 630 martensitic precipitation hardening stainless steel in order to optimize aging condition. Aging treatment was carried out with Ar gas in the chamber at temperature of 380°C, 400°C and 430°C and times of 2, 4 and 8 h. After obtaining the optimized aging condition, several nitrocarburizing treatments were done with and without the aging treatment. Nitrocarburizing was performed on the samples at 400V with a gas mixture of H2, N2 and CH4 for 15 hrs at 4.0 Torr vacuum pressure. The aging condition was optimized as 400°C temperature for 4 h. Better results were found when the samples were experimented with aging + nitrocarburizing treatment. In this combined process, the corrosion resistance improved noticeably which is confirmed by potentiodynamic polarization test and by observing the surface of the samples after corrosion test. Moreover, the surface hardness increases up to 1300 HV0.05 approximately and α'N layer thickness increases up to 11 μm (approximately).
Effect of Gas Content and Treatment Temperature on the Characteristic of Surface Layers of Low Temperature Plasma Nitrided 316L Austenitic Stainless Steel
Authors: Lee Insup
Published: December 2018

The effect of gas content and treatment temperature on the surface characteristics of hardened layers of low temperature plasma nitrided 316L Austenitic Stainless Steel was investigated. The process was performed at fixed processing time at 15Hr and changing the N2 content from 10% to 25%, changing the treatment temperature from 370 °C to 430 °C. The surface hardness and the thickness of expanded austenite (S-Phase) layer increase with increasing both temperature and nitrogen content. At 430°C processing temperature and 25% N2 content, the S-phase layer thickness increased up to 13 μm and surface hardness increased about 3.5 times of that of untreated sample which is 880 HV0.1 (before treatment 250HV0.1 hardness). However, the XRD pattern of the this sample shows the presence of γ'-(Fe,Cr)4N precipitation on the surface which is the reason for the increased corrosion current density that results in increased corrosion rate. Thus the corrosion resistance degrades and presents even worst behavior comparing that of before treatment. Therefore, for increasing the corrosion behavior, further research was conducted by fixing the N2 content at 10% with changing the CH4 content from 0% to 5%. The best results were found when treated at 430°C with 5% CH4 content. At this condition the S-phase thickness increase to around 17μm and surface hardness (980 HV0.1) is improved about 3.9 times of the hardness of untreated one. This sample also showed superior corrosion resistance than the other treated samples and the untreated one due to much higher pitting potential.
Effects of Surface Treatment for A5052 Aluminum Alloy on Adhesiveness between A5052 Aluminum Alloy and Engineering Plastics
Authors: Hino Makoto , Kuwano Ryoichi , Nagata Norihito , Nagata Kazuya , Kanadani Teruto
Published: December 2018

Effects of the surface-treated A5052 aluminum alloy on the adhesiveness of joining dissimilar materials, such as A5052 aluminum alloy sheet and polyamide resin sheet, was examined to manufacture a multi-material. Various surface treatments for the A5052 sheet were performed. The hot melt adhesive sheet comprising polyamide resin was used as the adhesive. The shear strength of adhered specimens was measured via tensile testing, and the shear strength was made to be the joining strength. Using various surface treatment techniques, oxidation films with different hole sizes and surface roughness were formed on the A5052 aluminum sheets. The joining strength of the surface-treated specimens was the lowest, whereas those joined via anode electrolysis exhibited the highest joining strength. These differences in joining strengths were owing to the anchor effect and chemical interfacial bonding force.
Effect of Interface Damage on Loosening Behavior of Acetabular Cup Subjected to Cyclic Loading
Authors: Otsuka Yuichi , Kagaya Kengo , Hakozaki Yuki , Miyashita Yukio , Mutoh Yoshiharu
Published: December 2018

This study aims at experimentally revealing the effects of damages/fractures in HAp coating layer of acetabular cups on loosening behavior of the acetabular cups. Aseptic loosening is occurred due to degradation of fixing force of acetabular cups by biological effects or mechanical loading. However, effects of mechanical loading on loosening behaviour have not been observed yet. In order to simulate cyclic loading conditions of gaits, a testing system which can load entire components of joint including acetabular cups and stem parts was designed. Moreover, by applying two positions of AE sensors during fatigue testing, it was possible to observe the damage behavior of HAp coating. AE measurement detected different failure modes of HAp coating, which were locally occurred at an edge part of the acetabular cup due to stress singularity at that region. In the cases of changing fixation angles, even though damages in simulated cancellous bone surrounding acetabular cups were less occurred, extents of rotational displacements were compatible with the one in an original fixation angle.
Amorphous Alumina Films Efficiently Protect Ti6242S against Oxidation and Allow Operation above 600 °C
Authors: Samelor Diane , Baggetto Loïc , Laloo Raphaël , Turq Viviane , Duguet Thomas , Monceau Daniel , Vahlas Constantin
Published: December 2018

The protection of the titanium based Ti6242S alloy against oxidation at moderate temperature is investigated, through the application on its surface of a 300 nm thick, amorphous alumina film. The latter is processed by metalorganic chemical vapor deposition at 500 °C from dimethyl aluminum isopropoxide. Upon oxidation at 600 °C for 5000 h, an interfacial zone is created between the alloy and the external protective layer, composed of unaffected alumina. In these conditions, the mass gain per unit area is eight times lower than that of the bare alloy, while the hardness of the alloy remains unaffected, revealing negligible oxygen ingress attributed to the efficiency of the protective coating. Finally, alumina coated samples show negligible mass change after 80 one-hour thermal cycles between 50 °C and 600 °C, showing excellent coating adherence on the Ti alloy.
Serial Production Applications and Application Development with Focus on Cold Spraying at Obz Innovation
Authors: Hartmann Sven , Trenkle Fabian
Published: December 2018

This paper deals with some of the latest developments and serial production applications at obz innovation gmbh. With three serial production systems and one for the R&D department, obz innovation gmbh is the leading supplier of cold sprayed coatings. The development of the well known serial production process of the sinusoidal copper coating for hybrid cars is explained. Furthermore our ferritic chromium steel induction coating and our new application paths in this area, an immanent temperature limitation function for safety critical reasons, is shown. An example for a field of research actually examined at obz is power electronics with cold sprayed circuits on an insulating ceramic coating with potential use in fields like automotive and many others.
Control Quality on Process of Laser Heat Treatment
Authors: Montealegre Maria Angeles , Arejita Beñat , Alvarez Piera , Laorden Carlos , Diaz-Rozo Javier
Published: December 2018

Laser surface hardening, is a process in which a shaped laser beam is scanned across the surface to produce a hard and wear-resistant surface on components. Compared with the conventional surface hardening process, the laser heat treatment offers a number of attractive characteristics such as minimal part distortion, self-quenching and the need for less finishing work. The challenge of laser hardening is the uneven surfaces found in molds such as those with sharp edges or holes. In these cases, due to the differences in the surrounding volume of the material, overheating problems often appear leading to unacceptable treatment results. The purpose of this paper is to present the new technology, “raio” developed by Talens System for laser hardening process. This technology is able to adapt to geometrical singularities of the components to be treated, ensuring the dimensions of the hardened area and hardness values are compliant with the requirements. The main features of the technology for laser hardening are validated on a set of samples of 1.2738 steel with representative discontinuities of molds. Mechanical and microstructural characterizations of the hardened cross sections confirm the advantages of the raio technology in regard to the quality compliance of the laser hardening process. Furthermore, raio offers the same advantages for other laser processes, like softening of critical area or laser cladding for repairing of damaged components.
Coating Toughness Estimation through a Laser Shock Testing in Ni-Cr-B-Si-C Coatings
Authors: Rolland G. , Cossange C. , Andrieu A. , Blat-Yrieix M. , Sallamand Pierre , Duband M. , Blanc C. , Aubry P. , Rouillard Fabien , Marlaud Thorsten
Published: December 2018

In the nuclear field, efforts are made to find substitutes to cobalt hardfacing alloys since these alloys have a principal drawback, the transmutation from stable 59Co to 60Co under neutron irradiation. In case of wear, fragments could be deposed on the surface of primary circuit and thus contaminate it, causing a real issue for deconstruction.
Development of Tool Steel Matrix Composites with High Thermal Conductivity
Authors: Sasaki Gen , Choi Yong Bum , Sugio Kenjiro , Matsugi Kazuhiro
Published: December 2018

The improvement of thermal conductivity of tool steel is extremely important for order to achieve life prolongation of metal die used in die-casting. In order to improve the thermal conductivity without the degradation of mechanical properties, VGCF (vapor grown carbon fiber) and TiB2 particles added in tool steel (SKD61) and to obtain the composites. Composites was fabricated by spark plasma sintering (SPS). Before sintering, SKD61 powders with 70μm in diameter and 1.9-3.8 vol. % VGCF with 0.15-0.2μm in diameter and 10-20μm in length or 4-8 vol. % TiB2 particles with 2.62μm in average diameter was mixed by V shape type ball milling or planetary ball milling. Composites were sintered at 1273K with 50 MPa. The relative density of all composites is higher than 97%. The thermal conductivity improved from 20W/mK to 36W/mK by adding 8 vol. % TiB2 particles, and to 25W/mK by adding 1.9 vol. % VGCF. On the other hand, the tensile strength of 1.9 vol. % VGCF/ SKD61 composites prepared under the condition of V shape type ball milling has 2200MPa. Composites with addition of 4vol. % TiB2 particles with V shape type ball milling and 1.9 vol. % VGCF with planetary ball milling is almost equal to the monolithic alloy. Good mechanical properties of the composites are caused by the grain refinement or interfacial strengthening by adding dispersants. But as increasing the contents of dispersants, the aggregation of the dispersants degrade the mechanical properties.
Texture and Mechanical Properties of IF Steel/Polyethylene/IF Steel Laminates
Authors: Hoshino Tomoaki , Inoue Hirofumi
Published: December 2018

It is possible for lamination of metal and plastic plates to add functionality such as damping and thermal insulation while maintaining the specific strength. IF steel/polyethylene/IF steel laminates were fabricated by warm rolling at two rolling reductions in thickness of 40% and 50%, and strength of the laminates and textures of the constituent layers were investigated in detail. From the ODF measurement, when the rolling reduction is high, polyethylene was oriented not only to [100]//RD but also to [001]//ND, resulting in biaxial orientation. Tensile strength of the IF steel layer was about 9 times higher than that of the polyethylene layer, and that of the laminate was almost consistent with the calculated value by the rule of mixture. The IF steel layer with much higher strength showed isotropic tensile strength related to the γ-fiber texture of <111>//ND, although the polyethylene layer showed remarkable in-plane anisotropy resulting from the strong texture. As a result, tensile strength of the laminates was isotropic for both rolling reductions.
Copper Effect on Mechanical Properties of Al-CNF Composite Material Elaborated by Liquid Metallurgy with Induction Melting
Authors: Royes Paul , Masquelier Nicolas , Breville Thierry , Balloy David
Published: December 2018

Aluminum-Carbon nanoFibers (CNF) composites produce by stir casting process present a yield strengths (YS) and an ultimate tensile strength (UTS) improved up to 33%. The hardening of the Al-CNF composite was considered as the sum of elementary contributions of effects: natural hardness of pure Al; grain size; dislocation density; elements in solid solution; CNF. In order to quantify CNF effect, calculation was performed to quantify the contribution to yield strength of each other’s mechanisms. This theoretical calculation was compared to experimental results and the real effect of CNF on yield strength increase was estimated between 10 and 16%. Figure SEQ Figure \* ARABIC 1: Graphical Abstract (copper dots on CNF / stir casting process / contributions to hardening) Keywords: Aluminum matrix composite; copper-coated carbon nanofibers; liquid metallurgy elaboration; mechanical properties; hardening effect
Control of Mechanical Properties of Functionally Graded Dual-Nanoparticle-Reinforced Composites
Authors: Kwon Han Sang , Park Je Hong , Kim Kwon Hoo , Leparoux Marc , Silvain Jean Francois , Kawasaki Akira
Published: December 2018

Functionally graded aluminium (Al) matrix composite materials reinforced with carbon nanotubes (CNT) and silicon carbide nanoparticles (nSiC) or nanodiamond (nD) were fabricated using a powder-metallurgical route. The nSiC and nD were not only used as a reinforcement but also as an active solid mixing agent for dispersing the CNT in the Al powder. Dual-nanoparticle-reinforced functionally graded multiple-layered composites were found to exhibit different mechanical characteristics. In particular, the hardnesses of the CNT-and nSiC-reinforced composites were dramatically increased, being up to eight times greater (330 HV) than that of bulk pure Al. In the case of the combination of the CNT and nD nanoparticles, the reinforced Al matrix composites exhibited the highest flexural strength (about 760 MPa). This functionally graded dual-nanoparticle approach could also be applied to other nanoreinforced systems, such as ceramics or complex hybrid-matrix materials. Keywords: Carbon nanotubes (CNT), nanosilicon carbide (nSiC), nanodiamond (nD), functionally graded materials (FGM), Powder metallurgy
Effect of Original Microstructure on Microstructure and Mechanical Properties of High Strength Steel WHF1500H during Hot Forming
Authors: Zhou Wen Qiang , Pan Li Bo , Hu Kuan Hui , Sun Wei Hua , Han Rong Dong
Published: December 2018

The press hardening steel sheets WHF1500H with different original structures produced by compact strip production (CSP) line in Wuhan Iron and Steel Ltd. were austenitized at 950 °C for 5 min, and then hot stamped and quenched by using the flat die. The microstructure and mechanical properties were investigated by optical microscope, transmission electron microscope and universal testing machine. The results show that the microstructure after stamping and quenching is fully composed of lath martensite. The mechanical properties of the steel samples with different original structures are different after hot stamping and quenching, and this difference is smaller than that before hot stamping and quenching. When the original structure consists of ferrite and pearlite, the austenite grains after austenitization are fine and uniform. In addition, the martensite structure obtained after hot stamping and quenching is also uniform and fine, leading to higher mechanical properties. With the increase of the strength of the original steel, when the original structure is martensite, the austenite grains after austenitization are coarse, and the martensite structures obtained after quenching is also coarse, and thereby decreasing the strength.
Photoluminescence of (ZnO)0.82(InN)0.18 Films: Incident Light Angle Dependence
Authors: Miyahara Nanoka , Iwasaki Kazuya , Yamashita Daisuke , Nakamura Daisuke , Seo Hyun Woong , Koga Kazunori , Shiratani Masaharu , Itagaki Naho
Published: December 2018

We have fabricated a new semiconducting material, (ZnO)x(InN)1-x (called ZION hereafter), which is a pseudo-binary alloy of wurtzite ZnO (band gap: 3.4 eV) and wurtzite InN (band gap: 0.7 eV). We have succeeded in fabricating epitaxial (ZnO)0.82(InN)0.18 films on ZnO templates by RF magnetron sputtering. XRD measurements show that the full width at half maximum of the rocking curves from (101) plane and (002) plane are significantly small of 0.11 ̊ and 0.16 ̊, respectively, indicating good in-plane and out-of-plane crystal alignment. High crystal quality of the films was also proved by deducing the defect density from XRD analysis showing that the edge type dislocation density is low of 8.2×108 cm-2. Furthermore, we observed room temperature photoluminescence from ZION films as a parameter of incident angle of He-Cd laser light. The results indicate that an emission peak of 2.79 eV is originated from ZION.
Internal Stress Evaluation on SiC Dices after SLID Process
Authors: Bettahi Yousra , Richard Caroline
Published: December 2018

Thin layers of intermetallic (IMC) were prepared using Solid-Liquid Inter-Diffusion (SLID) process. 3μm of Tin was deposited on SiC dice, then soldered on a copper substrate at different temperature: 250-300-330-370°C and different soldering times: 5sec-300 sec - 15 min - 1h. The composition of the IMC was identified using energy dispersive X-Ray spectroscopy (EDX). Two types of intermetallic layers were identified: Cu3Sn and Cu6Sn5. The samples were tested using die shear test. Then the internal stress was measured by X-Ray Diffraction (XRD). XRD spectrum obtained spotted only pure copper present underneath the intermetallic layer. The results showed that the level of residual stress is related to the amount of voids in the solder.
Electron Diffusion Length and Charge Separation Efficiency in Nanostructured Ternary Metal Vanadate Photoelectrodes
Authors: Binti Haji Yassin Siti Nur'ain , Halidi Nur Afifah Haniyyah , Sim Soong Leong , Liu Ye Ru , Jennings James Robert
Published: December 2018

Ternary metal vanadates have recently emerged as promising photoelectrode materials for sunlight-driven water splitting. Here, we show that highly active nanostructured BiVO4 films can be deposited onto fluorine-doped tin oxide (FTO) substrates by a facile sequential dipping method known as successive ionic layer adsorption and reaction (SILAR). After annealing and deposition of a cobalt phosphate (Co-Pi) co-catalyst, the photoelectrodes produce anodic photocurrents (under 100 mW cm-2 broadband illumination, 1.23 V vs. RHE) in pH 7 phosphate buffer that are on par with the highest reported in the literature for similar materials. To gain insight into the reason for the good performance of the deposited films, and to identify factors limiting their performance, incident photon-to-electron conversion efficiency spectra have been analyzed using a simple diffusion–reaction model to quantify the electron diffusion length (Ln; the average distance travelled before recombination) and charge separation efficiency (ηsep) in the films. The results indicate that ηsep approaches unity at sufficiently positive applied potential but the photocurrent is limited by significant charge collection losses due to a short Ln relative to the film thickness. The Co-Pi catalyst is found to improve ηsep at low potentials as well as increase Ln at all potentials studied. These findings help to clarify the role of the Co-Pi co-catalyst and show that there could be room for improvement of BiVO4 photoanodes deposited by SILAR if Ln can be increased.