bluuebunny/crossref_metadata_2025 huggingface dataset:
High Temperature Mechanical Properties of Harmonic Structure Designed SUS304L Austenitic Stainless Steel
Authors: Nakatani Masashi , Fujiki Yuya , Ota Mie , Vajpai Sanjay Kumar , Ameyama Kei
Published: November 2016

Through many years, conventional material developments have emphasized on microstructural refinement and homogeneity. However, "nanoand Homogeneous "microstructures do not, usually, satisfy the need to be both strong and ductile, due to the plastic instability in the early stage of the deformation. As opposed to such a “nanoand homo-“microstructure design, we have proposed “Harmonic Structure” design. The harmonic structure has a heterogeneous microstructure consisting of bimodal grain size together with a controlled and specific topological distribution of fine and coarse grains. In other words, the harmonic structure is heterogeneous on micro-but homogeneous on macro-scales. In the present work, the harmonic structure design has been applied to SUS304L austenitic stainless steel via a ball milling process and a large size (50 mm in diameter) SPS sintering process. At a macro-scale, the harmonic structure SUS304Lcompacts exhibited significantly better combination of strength and ductility, under quasi-static tensile loadings, as compared to their homogeneous microstructure counterparts. High temperature tensile tests revealed that they also indicated high strength at elevated temperatures.
Microstructure and Mechanical Properties of Nb Alloyed Steel Processed by Hot Equal Channel Angular Extrusion
Authors: Yanagida Akira , Aoki Ryo , Kobayashi Masataka
Published: November 2016

A Nb alloyed low carbon steel was processed by hot equal channel angular extrusion (ECAE) and following transformation. The workpieces were heated up to the 960°C in the furnace for 10 min within the container block. Before extrusion, the die was preheated to 400oC. The workpiece was cooled in the die after ECAE process. 1 pass and 2 pass via route C were conducted at a speed of 32mm/s, the inter-pass time is about 2 sec. The sample of average ferrite grain size of about 2μm, a tensile strength of 800MPa, a total elongation about 20% is produced after 2 pass ECAE processed and subsequent cooling.
Study of the Precipitation of Secondary Phases in Duplex and Superduplex Stainless Steel
Authors: Llorca-Isern Nuria , López-Jiménez Isabel , López-Luque Héctor , Biezma Maria Victoria , Roca Antoni
Published: November 2016

The aim of this work is to study the precipitation mechanism of the intermetallic phases present in duplex stainless steels (UNS S32205 and UNS S32750), as well as to find out the most suitable method for detecting and analyzing accurately these secondary phases, particularly Sigma-phase, Chi-phase, nitrides and carbides. The samples were characterized after a solution annealing at 1080oC followed by an isothermal treatment at 830oC from 1 min to 9 h, with the purpose of figuring out the mechanism of chi-phase nucleation and nitrides formation in relation with the sigma-phase. The study has two main objectives: 1) to find out the most suitable technique for the detection, identification and quantification of the secondary phases, obtaining the best results with the combination of field emission scanning electron microscopy (FESEM) and backscattered electron detector (BSE) in comparison with the optical microscopy (MO); 2) to study the influence of the chemical composition on the nucleation mechanism of the intermetallic phases. It has been concluded that molybdenum balance content in chi-phase related to sigma phase is close to two, consequently the kinetics of nucleation and growth of these phases is remarkably faster when this alloying element content in the steel is higher. Chromium nitrides and carbides were also observed to precipitate as a result of the heat treatments carried out to the specimen wherein chromium nitrides role is a favorable site for the nucleation of sigma and chi phases.
Practical Use of Computer Model STAN 2000 for Improvement and Creation of Regimes for Hot Rolling of Steels on SEVERSTAL Mill 2000
Authors: Ogoltcov Alexey A. , Sokolov Dmitry , Sokolov Semen , Vasilyev Alexander A.
Published: November 2016

An integral computer model STAN 2000 designed for of-line simulation and control of hot rolling on mill 2000 of SEVERSTAL was developed. The capabilities of the model include the following features: ‒ calculations of power parameters for all stands of mill 2000 for a given rolling schedule; ‒ strip temperature calculations depending on selected rolling and accelerated cooling regimes; ‒ follow-up of steel microstructure evolution at all stages of strip production and prediction of ultimate mechanical properties (yield stress, ultimate tensile stress, relative elongation and toughness); ‒ optimization of rolling regimes for existing steel grades and developing them for a new one. The STAN 2000 program is written in С++ programming language and can work on all modern Microsoft Windows family operating systems. The program has a well-designed and user-friendly interface facilitating its practical use. The integral model was calibrated using an extensive data base on rolling regimes and forces, measured temperatures and final mechanical properties for a number of steel grades rolled on mill 2000 of SEVERSTAL with chemical compositions covering the following range of alloying elements content (mass.%): С(≤0.65); Mn(≤2.0); Si(≤1.0); Cr(≤0.9); Ni(≤0.6); Cu(≤0.5); Mo(≤0.4); Nb(≤0.05); V(≤0.065); Ti(≤0.06); B(≤0.003). The examples of STAN 2000 program use in practice of industrial hot strip production on mill 2000 of SEVERSTAL are presented and discussed.
Electrochemical Behaviors of Biomedical Nanograined β-Type Titanium Alloys
Authors: Yilmazer Hakan , Dikici Burak , Niinomi Mitsuo , Nakai Masaaki , Lui Hui Houng , Todaka Yoshikazu , Ozcivan Ahmet Nuri
Published: November 2016

The microstructural evolution and its effect on biocompatibility of TNTZ through HPT processing were investigated systematically in this study. TNTZAHPT shows an enhanced mechanical biocompatibility, which is characterized by a higher tensile strength (1375 MPa) and hardness (450 HV) than those of TNTZST, TNTZAT, and Ti64 ELI while maintaining a relatively low Young’s modulus. In this study, such microstructural refinement of TNTZ and its effect on electrochemical biocompatibility through HPT processing are investigated systematically in this study. The microstructure of TNTZAT consists of randomly distributed needle-like α precipitates in the equiaxed β grains with a diameter of approximately 40 m. The microstructure of TNTZAHPT consists of nanograined (NG) elongated β grains that have subgrains of non-uniform morphologies resulting from distortion by severe torsional deformation. Furthermore, the β grains and subgrains are surrounded by non-equilibrium grain boundaries. The needle-like α precipitates are completely refined to a nanograined. TNTZAHPT exhibits an enhanced combination of excellent corrosion performance and improved cellular response compared to TNTZST, TNTZAT, and Ti64 ELI.
Numerical Simulation of the Effects of Preheating on Electron Beam Additive Manufactured Ti-6Al-4V Build Plate
Authors: Cao Jun , Nash Philip
Published: November 2016

In an earlier study, a 3-D thermomechanical coupled finite element model was built and experimentally validated to investigate the evolution of the thermal residual stresses and distortions in electron beam additive manufactured Ti-6Al-4V build plates. In this study, an investigation using this robust and accurate model was focused on an efficient preheating method, in which the electron beam quickly scanned across the substrate to preheat the build plate prior to the deposition. Various preheat times, beam powers, scan rates, scanning paths and cooling times (between the end of current preheat scan/deposition layer and the beginning of the next preheat scan/deposition layer) were examined, and the maximum distortion along the centerline of the substrate and the maximum longitudinal residual stress along the normal direction on the middle cross-section of the build plate were quantitatively compared. The results show that increasing preheat times and beam powers could effectively reduce both distortion and residual stress for multiple layers/passes components.
Friction Stir Processing at High Rotation Rates of a Magnesium Alloy: Mechanical Properties at High Temperatures and Microstructure
Authors: Cerri Emanuela , Renna Gilda , Cabibbo Marcello , Simoncini Michela , Forcellese Archimede
Published: November 2016

A high-pressure die-cast magnesium alloy plate was friction stir processed at high rotation rates with different advancing speeds. The stirred zone was very narrow around the tool and this made the friction stir process difficult to occur in the whole thickness of the plate. Intermetallic-phase network at grain boundaries was refined due to partial dissolution and fragmentation of Mg17Al12 β-phase during the friction stir process; the likely increment of solute content in solid solution was exploited for aging to improve hardness. The ductility of friction stir processed samples deformed at 300° and 350°C substantially increased compared to the base material and to room temperature strained samples.
Effects of Precipitated Particles on Microstructure Evolution during Thermo-Mechanical Processing of Al-Zn-Mg-Cu Alloy
Authors: Chen Hui Qin , Zhang Kun , Zhao Xiao Dong
Published: November 2016

Two intermediate thermal mechanical treatment (ITMT) Processes were designed for investigation the influence of multi-scale precipitated particles on microstructure evolution during thermo-mechanical processing of Al-7.6Zn-1.5Mg-1.75Cu-0.12Zr alloy by hot compressive experiments and microstructure testing of OM and EBSD. It is found that the size and distribution of precipitated particles preprocessed by over-aging at 400°C for14h can meet the particle stimulated nucleation of recrystallization. Refined and uniform grains present in the sample after hot deformation at about 20 of LnZ up to 80% reduction and subsequent final solid solution treatment. But for samples preprocessed by solid solution at 435°C for 2h and aging at 200°C for 12h, Refined uniform recrystallized grains or recovery sub-grains in elongated grains present in the samples after hot deformation at about 25 of LnZ up to 60% reduction followed by annealing at 350°C for 0.5h and final solution treatment.
In Situ Characterisation of Austenite/Ferrite Transformation Kinetics and Modelling of Interphase Precipitation Inter-Sheet Spacing in V Microalloyed HSLA Steels
Authors: Clark Samuel , Lan Yong Jun , Janik Vit , Rijkenberg Arjan , Sridhar Seetharaman
Published: November 2016

A new generation of low-carbon microalloyed High Strength Low Alloy (HSLA) steels has been developed to utilize a combination of single-phase ferritic microstructures and optimized interphase precipitation to provide high level strength and exceptional formability. The interphase precipitation reaction is a transient process lending itself strongly to take advantage of in-situ characterization techniques. The austenite/ferrite interface kinetics during isothermal transformation at 1003 K is measured using HT-CSLM, the pre-exponential effective mobility constant was found to be mobility 0.822 (m J)/(mole s). The V interphase precipitation is characterised using TEM at isothermal transformation temperatures of 923 and 973 K as having inter-sheet spacing of 22±7 and 32±9 nm respectively. Interphase precipitation inter-sheet-spacing is simulated using a revised Quasi-Ledge model and qualitatively predicts the observed trends observed for inter-sheet spacing. The results of in-situ characterisation and modelling suggest that it is possible to optimize the strengthening potential of the precipitation processes by controlling the thermal processing of microalloyed HSLA.
Correlation between Aging Effects and High Temperature Mechanical Properties of the Unmodified A356 Foundry Aluminium Alloy
Authors: di Giovanni Maria Teresa , Cerri Emanuela , Merlin Mattia , Casari Daniele , Arnberg Lars , Garagnani Gian Luca
Published: November 2016

In this study, the effect of aging on the mechanical properties of unmodified A356 aluminium casting alloy with trace additions of Ni or V was investigated. Trace elements were added in concentrations of 600 and 1000 ppm of Ni and V, respectively. Samples from sand and permanent mould castings in as cast and T6 heat-treated conditions were tested. Tensile tests were performed at both room and high temperature (235 °C). Taking into account the results from both testing conditions, Vickers hardness was measured in order to endorse the hypothesis of artificial aging occurring during high temperature tensile tests. In order to study this effect, a series of specimens was aged at 235 °C for different aging times, and aging curves were plotted. The occurrence of static and dynamic aging was evaluated by comparing hardness values of tensile specimens and aged samples, particularly in the range of 5-20 min, as this range corresponds to the time necessary for pre-heating and testing of the tensile samples. A basic correlation between tensile strength and hardness is also given.
The Microstructural Criterion for Creep Strength Breakdown in a 10%Cr Martensitic Steel
Authors: Dudova Nadezhda , Mishnev Roman , Kaibyshev Rustam
Published: November 2016

A 10%Cr martensitic steel with 3%Co and 0.008%B tempered at 770°C exhibits no creep strength breakdown at a temperature of 650°C up to an extremely high rupture time of ∼4×104 h under an applied stress of 120 MPa. The minimum creep rate was ∼3×10-11 s-1. Microstructural characterization showed that superior creep resistance associated with a high stability of tempered martensite lath structure. Boundary M23(B⋅C)6 phase particles are highly stable against coarsening under long-term aging and creep conditions. These particles retain their orientation relationship with ferritic matrix unchanged under creep at a temperature of 650°C. As a result, no migration of lath boundaries and their transformation to subboundaries diminishing the long-range elastic stress fields take place. The role of M(C,N) carbonitrides in achieving extraordinary high creep strength consists in hindering the knitting reaction between mobile lattice dislocations and lath boundaries.
SPD Processed Materials Mechanical Properties Determination with the Use of Miniature Specimens
Authors: Džugan Jan , Konopík Pavel , Procházka Radek , Trojanová Zuzanka
Published: November 2016

The main reason why new technologies and treatment procedure are being developed is to attain special mechanical properties. However, these developments are nowadays done on a small material volume either using some laboratory simulators, applying sever plastic deformation procedures or chemical composition screening for multicomponent alloys development by laser or electron beam melting. In all these application a small volume of the material assessed is available and standard procedures for crucial mechanical properties determinations are not applicable. Thus small size techniques should be applied.
There has been extensively used small punch test technique (SPT) for those cases in recent years. This technique is mainly based on the evaluation using correlation between standard and SPT tests for considered material. In cases when insufficient material volume is available, those correlations cannot be established and thus comparative evaluation only can be carried out. This kind of evaluation is insufficient for the contemporary purposes, when full material potential is to be utilized. Therefore, procedures providing results directly comparable with standard specimens are being developed. Fundamental properties are those determined from tensile tests. The current paper is presenting application of developed miniature tensile test specimen method to materials after SPD processes. Quasi static properties determination is shown here for Magnesium and Titanium alloys for ECAP and Rotary Swaging SPD techniques. The results obtained from testing can be used not only for a direct material properties assessment and comparison, but also as input data for FEM codes, significantly increasing the materials considered application potential assessment.
Physical Simulation of Thermo-Mechanical Processing of Ferritic-Bainitic Dual Phase (FBDP) Steel
Authors: El-Bitar Taher , El-Shenawy Eman , El-Meligy Maha
Published: November 2016

The present work is dealing with a physical simulation of thermo-mechanical processing of ferritic-bainitic dual phase (FBDP) steel alloy containing 0.1% C, 0.3% Si, 0.9% Mn and 0.7% Cr. The microstructure changes and allotropic transformations during thermo-mechanical simulation are investigated. A series of heating – cooling cycles to detect the critical and allotropic transformation temperature by dilatation were carried out on the thermo-mechanical simulator (Gleeble 3500). On the other hand, five – consecutive hits were used during the physical simulation of hot rolling process. Two hits were representing the roughening stage followed by three ones representing finish rolling. Holding at 500°C for 5, 7, 10, 12 and 15 min. after last hit has been applied and then followed by air cooling.
Dilation curves appear that Ac1= 766 °C, while Ac3 was detected as 883 °C. Baintic allotropic transformation temperatures were clearly noticed as 618 °C for Bs and 542 °C for Bf. The recrystallization temperature was also detected as 1035 °C. Holding for 5-7 min. at 500 °C was concluded as the optimum for creation a bainite volume fraction. Rough hot deformation a higher temperature above the recrystallization temperature is essential, where no strain hardening and possibility for achieving high strains without excessive loads. Finishing deformation at temperature lower than Tr would create fine bainitic structure.
The flow curve of the steel ensures continuous strain hardening. The strain hardening rate (σf/ε) was directly proportional to temperature difference from pass to pass.
Influence of Cross Section on the Parameters for Linear Friction Welding of High-Strength Chains
Authors: Rath Gerald , Fuchs Franziska , Enzinger Norbert
Published: November 2016

In respect of weld quality, weld strength and the heat affected zone (HAZ) size, linear friction welding (LFW) has significant advantages compared to flash-butt and resistance welding. The production of chain links is realized by one c-shaped part in reciprocating motion being moved towards a stationary one under applied forces. The friction at the contact faces causes heat and thus, the material is plastically deformed. Due to relative movement excessive material is pressed out of the joint area leading to a characteristic weld burr. Relative motion is stopped once the defined burn-off is reached and by applying the forge force the chain is welded.
In this paper, welding parameters for three different cross sections are investigated. Based on successful welding trials on 30CrNiMo8 steel chains with 26 mm diameter, parameters are adapted for smaller cross sections. On 48 steel specimens with 7, 10 and 15 mm diameter systematic welding trials are performed. The influence of the welding parameters frequency, amplitude, forge force and burn-off on welding strength and welding time are investigated with and without application of heat treatment. This test series was evaluated using DoE.
Accelerated Aging and Portevin-Le Chatelier Effect in AA 2024
Authors: Delaunois Fabienne , Denil Edwin , Marchal Yves , Vitry Véronique
Published: November 2016

AA2024 aluminium alloy is used in aeronautics for various applications. However, the aging treatment (“T4 temper”) at ambient temperature used to bring it to optimal mechanical properties causes several problems. The main one is its duration (5 days) which brings the need for storage of the parts. Moreover temperature control during such a long period is difficult.The aim of this work was to develop an alternative treatment leading to optimized mechanical properties in a shorter time. For this, we investigated the kinetics of the aging process and observed the apparition and disappearance of “Portevin-Le Chatelier (PLC) effect” in AA2024 aluminium alloy.The knowledge of the time at which PLC effect is observed is important in terms of process because shaping may be carried out before the end of the aging process.
Granulation of Bulk Metallic Glass Forming Alloys as a Feedstock for Thermoplastic Forming and their Compaction into Bulk Samples
Authors: Geissler David , Grosse Jacob , Donath Sven , Ehinger David , Stoica Mihai , Eckert Jürgen , Kühn Uta
Published: November 2016

The various technologically important properties of metallic glasses are intimately connected to their amorphous structure that lacks the archetypical structural defects of polycrystalline metals and alloys, i.e. dislocations and grain boundaries. However, the amorphous structure also limits the application potential of this class of materials because of a macroscopically brittle behavior and size limitations. Consequently, with some exceptions, at least one dimension for technological products is limited to a few millimeters or even less. With the presented technological approach this drawback will be addressed. Our first results on several alloys show that with a dedicated instrumentation amorphous granulates can be successfully produced. By hot pressing in the supercooled liquid region, these granulates can be compacted into bulk shapes in the cm range. Further, due to the low viscosity of the supercooled liquid state, this technology disposes of a high formability. It is demonstrated that not only compact samples but also complex shapes in near net shape geometry can be produced. Results on the mechanical properties and microstructure will be discussed and related to important processing issues. Even though this technological approach does not directly address the second drawback of bulk metallic glasses, i.e. catastrophic failure due to highly localized shear bands, it is believed that this route offers possible pathways to improve this issue as well and, most important, to offer a technological route for implementing bulk metallic glasses into products of rather arbitrary shape and larger size.
Development of Polymer-Based Composite Coatings for the Gas Exploration Industry: Polyoxometalate Doped Conducting Polymer Based Self-Healing Pigment for Polymer Coatings
Authors: Mishra Brajendra , Chaudhry A. , Mittal Vikas
Published: November 2016

This study deals with the evaluation of self-healing ability of conducting polymer corresponding to a corrosion process. Poly ortho-anisidine (PoA) was doped with Phosphomolybdic acid (PMA) and Tungstosilicic acid (TSA) and incorporated in polyvinyl butyral (PVB) coatings. The self-healing abilities of coatings were evaluated using open circuit potential (OCP) in 0.1 M NaCl solution for 45 hours of immersion. The coatings containing doped PoA showed increased positive potential of OCP after 45 hours of immersion as compare toblank PVB which showed a constant profile of OCP over the time indicating uniform corrosion under the coating.Thermogravimetric analysis (TGA) showed that PoA doped with TSA is more stable and more effective in the coating. High resolution Transmission Electron microscopy (HR-TEM) and Energy dispersive x-ray spectroscopy (EDX) confirms the doping of PoA.
Local Residual Stress Depth Distribution in the Inner Gearing of a Case Hardened Sliding Collar
Authors: Gibmeier Jens , Rebelo-Kornmeier Joana , Strauss Tobias
Published: November 2016

With respect to residual stress analysis the inner gearing of an automotive sliding collar is a component with a challenging, complex geometry. The accessibility of the tooth root does not exist for conventional measuring approaches. However, the process steps like e.g. broaching and case hardening induce characteristic residual stress distributions, which must be known for the valuation of the mechanical integrity of the parts. For lab X-ray stress analysis approaches according to the sin2ψ-method [1] the ring like structure must be sectioned, which affects the process induced residual stress state. The tooth root is rather small, which further leads to shadowing effects during tilting of the sample. Standard mechanical approaches like incremental hole drilling can be excluded due to the narrow tooth root. Local neutron diffraction residual stress analysis in the tooth root by means of neutron through surface strain scanning at the STRESS-SPEC instrument at the research reactor FRM II, Garching (Germany) was successfully carried out for the inner gearing. A measuring and evaluation strategy is proposed, where special attention is paid to the compensation of the surface effect due to the incomplete immersion of the nominal gauge volume during through surface scanning and to the local variation of the D0-value as a consequence of the case hardening process.
Creep Tendencies of Cu-Al Thin Wires Submitted to Moderate Temperature Conditions: Influence of Intermetallic Compounds
Authors: Gueydan Antoine , Hug Eric
Published: November 2016

X-Ray analysis was performed on copper-clad aluminum wires at 423 K and 673 K to follow their microstructural evolution and understand their strain behavior under creep deformation, potential operating load in automotive industry. The lifetime of the wires is found to be strongly dependent on the existence of an initial heat treatment and on the applied stress. Annealed drawn wires verify a traditional Norton law in the overall range of the stress level. Raw drawn wires exhibit a distinct two stage behavior with a breakdown around an applied stress of 0.7 times the yield stress. It is shown in this work that the intermetallic compounds between copper and aluminum play only the role of a mechanical bounding without affecting the strain rate of the wires.
Torsional Piezoelectric Strain in Monocrystalline Paratellurite
Authors: Boivin Guillaume , Bélanger Pierre , Zednik Ricardo J.
Published: November 2016

Crystals of the 422 symmetry class exhibit interesting piezoelectric behavior, as their piezoelectric tensor has only a single non-zero coefficient, d123 = d14: such unique behavior has the potential to enable novel gyroscopic sensors and high-precision torsional MEMS actuators. Although alpha-phase tellurium dioxide (paratellurite, alpha-TeO2) is one of the few materials belonging to this symmetry class, this material has been primarily studied for its interesting optical properties. Indeed, a large uncertainty in the piezoelectric coefficient of paratellurite exists, with d123 measurements on single crystals ranging from 8.13 pC/N to 14.58 pC/N; this large uncertainty results from the difficulty in using conventional piezoelectric characterization techniques on paratellurite, and impedes adoption of this extraordinary material. The present study characterizes the piezoelectric behavior of this interesting material using two independent techniques, (1) a three dimensional laser Doppler interferometer system, and (2) electrochemical impedance spectroscopy (EIS). The experimental results are analyzed using numerical simulations for dynamic excitation conditions over a frequency range of 20 Hz to 200 kHz.
High Performance Magnesium Based Composites Containing Nano-Length Scale/Amorphous/Hollow Reinforcements
Authors: Gupta Manoj , Wong Wai Leong Eugene
Published: November 2016

Magnesium is the lightest weight metallic material that can be used in multiple engineering applications and biomedical sector as a structural material. It is abundantly available in earth’s crust and sea water and non-toxic in nature. Inherent to magnesium is its superior specific mechanical properties, high damping, electromagnetic shielding capability and ability to reduce carbon signature of the transportation sector.Magnesium is one of the widely available metal in earth crust and sea water. It is non-toxic and hence does not pose a health risk during recycling or waste dumping in natural water bodies. As a result, magnesium technology is sustainable and beneficial to planet earth and living organisms.Magnesium based materials are gradually being used in many applications and their performance and applications can further be stretched using the composite technology. Accordingly, the main scope of this paper is to highlight the enhancement of a number of properties of magnesium through the use of nanolength scale, amorphous and hollow reinforcements.
Recrystallization Behavior of Aluminum Thin Foils with Various Purity
Authors: Lee Hyun Woo , Min Seok Hong , Ha Tae Kwon
Published: November 2016

Recrystallization kinetics of aluminum with various purities from 99.5 to 99.999(5N) has been investigated in this study. Aluminum plates of 10 mm thickness with various purities were solution-treated at 400oC for 24 hrs and then rolled into sheets of 50 μm thickness at room temperature. Cold rolling was conducted on samples with various purities from 99.9 to 99.999 including commercial AA 1050 Al alloy and high purity through about 20 passes to obtain thin foils of 50 μm thickness. Accumulative rolling was employed when sample thickness reached at 1 mm and thin foils were successfully obtained for all samples. Hardness was measured just after cold rolling at room temperature as a function of time up to 1hr to elucidated recrystallization behavior. For aluminum with 99.999% purity, recrystallization occurred after 200 s and finished at 360 s. Recrystallization kinetics of aluminum at high temperatures from 100 to 350oC were investigated by measure hardness after annealing thin foils for various time intervals ranging from 1 s to 24 hrs. For high purity sample with 99.999% purity, recrystallization finished just after 1 s even at the relatively low temperature of 100oC, while recrystallization of commercial AA 1050 (2N) alloy finished after 360 s at 350oC.
Progress in Titanium Machining
Authors: Haas Franz , Zopf Philipp , Edler Jörg
Published: November 2016

Milling and drilling of titanium alloys represent a key technology for the aircraft manufacturers. The balancing act between production costs and tool costs leads to the need of tests and an optimized setup of the whole process. A Styrian consortium with experts in materials, tools and machining has been formed to extend the tool life in machining of titanium alloys. A series of tests is set up to evaluate the roughing and finishing operations. For finishing operations ultrasonic assisted milling is introduced and compared with conventional milling. Force measurement and optical wear detection are used for tool characterization.
Reinforcing Open Cell Aluminum Foams by Amorphous Ni-P Coating
Authors: Li Zhen Dong , Huang Ying Jie , Wang Xin Fu , Wang Xing Fu , Han Fu Sheng
Published: November 2016

Open cell aluminum foams are a promising multi-functional material that has potential application in a variety of engineering fields, but their too low mechanical properties may restrict their applications in some load bearing conditions. To overcome this shortcoming, enhancement methods have been widely investigated in recent years including surface enhancement technologies. In the present study, an electrodeposition process was utilized to coat an amorphous Ni-P coating on the cell strut surface of open cell aluminum foams. The results show that the coated film exhibits typical amorphous feature and is thermally stable. The average nanohardness and Young’s modulus are 7.0GPa and 118.1GPa, respectively, in which the Young’s modulus is even 1.6 times higher than that of aluminum (70GPa). It is because the high strength film that leads to significantly enhancement of the foams. The compression strength of the foam was increased from about 0.2MPa to 11.9MPa when the film thickness was around 65μm. These results demonstrate that the surface coating does be an effective way to improve the mechanical properties of open cell aluminum foams.
Preparation of Al72Ni8Ti8Zr6Nb3Y3 Amorphous Powder and Bulk Material
Authors: Wu Yu , Wang Xin Fu , Han Fu Sheng
Published: November 2016

Al-based amorphous materials are believed to be a promising light weight and high strength material, but the application has not yet been realized due to difficulties in fabricating bulk materials resulted from their quite weak glass forming ability. In order to overcome this difficulty, a solid state route was studied to fabricate bulk Al-based metallic glass. An amorphous Al72Ni8Ti8Zr6Nb3Y3 powder was first fabricated by mechanical alloying, and then the microstructure, glass-forming ability and crystallization behavior were characterized. The powder shows a wide supercooled liquid region (81K), and high activation energy for crystallization (312.6kJ/mol). By this powder, a bulk material was fabricated through high pressure (2GPa) sintering (673K and 723K). The microhardness of bulk sample is as high as 1215Hv, providing a solid basis for fabricating bulk materials and applications.
X-Ray and Neutron Scattering Studies of the 9Ni Cryogenic Steel and its Weld Joint
Authors: Hany Sara , Duponchel Benoit , Aboukaïs Antoine , Bychkov Eugene , Aad Edmond Abi
Published: November 2016

To guarantee the reliability and safe operation of large-scale metallic structures exposed to cryogenic temperatures for extended periods, it is important to evaluate structural properties of the base metal as well as the welded zone in order to prevent damages that could occur. Spatially-resolved high-energy synchrotron diffraction, pulsed neutron diffraction and small-angle neutron scattering have been used to study short, intermediate and mesoscopic range order in cryogenic 9Ni steel as well as the structural changes induced by the welding. Pristine 9Ni steel appears to be a metastable Fe-Ni alloy with main bcc martensitic phase and a minority fcc austenitic phase. Welding of 9Ni steel using SMAW technique has revealed a fast intergranular nickel diffusion at high temperatures during welding originated from high nickel content in the SMAW welding alloy.
In Situ Tensile Texture Analysis of a New Mg-RE Alloy
Authors: Gan Wei Min , Huang Yuan Ding , Xu Yu Ling , Hofmann Michael , Kainer Karl Ulrich , Hort Nobert
Published: November 2016

A new Mg-RE (rare earth) alloy was previously developed by micro-alloying method (RE< 0.4 wt.%), which achieves a high ductility and good corrosion resistance. In-situ tensile test via neutron and synchrotron diffraction were performed to investigate first the deformation behaviour; and second the texture evolution which can be related to the deformation mechanism, and finally to understand why the as-cast Mg-RE alloys show such a high tensile ductility.Preliminary results showed that a dominated basal fibre texture was gradually developed with the increase of tensile strain. However, before the sample was broken a (10.0) fibre texture showed a similar intensity to that in (00.2), which means more activations of the non-basal slip planes during tensile deformation. This could also contribute to a relatively high elongation of this new Mg-RE alloy at room temperature. Further discussion will be showed together with the microstructures.
Study on the Porosity in Al-Zn-Mg-Cu High Strength Alloy DC Ingot
Authors: Jiang Hui Xue , Nagaumi Hiromi , Guo Shi Jie , Zou Chun
Published: November 2016

An Al-Zn-Mg-Cu high strength alloy ingot produced by Direct-Chill casting was used in this study. The distribution of porosity in the cross section of the DC ingot was investigated by the precision density method (Archimeds’ principle), also X-ray microtomography technique was used to quantitatively analyze porosities in typical positions. The pattern in the cross section as well as in the thickness and width direction was obtained. The results show that: in the cross section of the ingot, porosity was increasing gradually from the surface to the center of the ingot; porosity shows an overall escalating trend from the surface to the center of the ingot both in thickness direction and in width direction; porosity was closely related to the cooling rate in the ingot; oxide inclusions have an effect on the formation of porosity to some extent.
Effect of Annealing upon Retention of He and H in Irradiated SiC
Authors: Ionescu Mihail , Deslandes Alec , Holmes Rohan , Guenette Mathew C. , Karatchevtseva Inna , Lumpkin Gregory R.
Published: November 2016

Silicon carbide (3C-β SiC) samples were irradiated with He ions of energy up to 30 keV and a fluence up to 1016/cm2, to produce damage in the near-surface region. A duplicate set of He ion irradiated SiC samples, as well as undamaged SiC, were also irradiated with H2+ ions of energy up to 20 keV and a similar fluence, to study the interaction of H species with pristine SiC and with He radiation-damaged SiC. Samples were annealed in steps of 200 K, from 473 K to 1273 K, and the retention of H and He were measured using elastic recoil detection analysis with 7.8 MeV C3+ ions, after each anneal step. Modification to the surface following irradiation is observed via Raman spectroscopy, which exhibits development of damage states such as disordered carbon and Si-Si peaks. Only minor changes in the H and He profiles were observed up to 1073 K, however after the 1273 K anneal the H and He profiles changed considerably, with a marked difference between samples irradiated only with He and those irradiated with He and H.
Al-5Cu Alloy Processed by Equal-Channel Angular Pressing
Authors: Jia Hai Long , Marthinsen Knut , Li Yan Jun
Published: November 2016

An ECAP (equal channel angular pressing) processed UFG Al-5Cu alloy was characterized by electron backscatter diffraction (EBSD). It is revealed that a bimodal grain structure, i.e. ultrafine grains accompanied by micron-sized grains was developed after 4 passes. A high strength (~501 MPa) and a relatively large elongation to failure (~28%) with ~5% uniform elongation were achieved simultaneously after 4 passes of ECAP. The high strength is due to a combination of strengthening by solute, high density of dislocations and ultrafine grains. The enhancement of uniform elongation is primarily due to the enhanced work hardening resulted from the solute Cu content and the bimodal grain structure. The large post-uniform elongation is attributed to the high strain rate sensitivity of the UFG Al-5Cu alloy. More importantly, the present work revealed that during ECAP high solid solution content of Cu and coarse secondary phase particles can introduce inhomogeneous deformation resulting in a desirable bimodal grain structure, which can be utilized as a strategy to gain both high strength and relatively good ductility.
Thermomechanical Processing of Medium Manganese Steels
Authors: Ito Atsushi , Shibata Akinobu , Tsuji Nobuhiro
Published: November 2016

As third generation advanced high strength steels (AHSS) managing both high strength and good ductility/formability, medium manganese steels containing 3-7 wt% Mn have attracted attentions recently. However, the fundamental microstructure evolution during thermomechanical processing and heat treatments in medium-Mn steels is still unclear. In the present study, changes in microstructure and mechanical properties during various heat treatments and thermomechanical processes of 4Mn-0.1%C steel were studied. It was clarified from dilatometric measurements that ferrite transformation in the 4Mn-0.1C steel was quite slow, so that fully martensitic structures were obtained in many cases after cooling from austenite. On the other hand, hot-deformation of austenite greatly accelerated ferrite transformation, and dual phase microstrcutures composed of ferrite and martensite could be obtained. The dual phase steel showed good combinations of high strength and adequate tensile ductility.
Fiber Laser Beam Welding of Ti-6242 - Effect of Processing Parameters on Microstructural and Mechanical Properties
Authors: Kashaev Nikolai , Pugachev Dmitry , Riekehr Stefan , Ventzke Volker
Published: November 2016

The present work investigates the effects of laser beam power, focus position and advance speed on the geometry, microstructure and mechanical properties of fiber laser beam welded Ti-6Al-2Sn-4Zr-2Mo (denoted as Ti-6242) butt joints used for high temperature applications. Detailed microstructural and mechanical studies were performed on welds produced using optimized parameters (a laser beam power of 5 kW, a focus position of 0.0 mm and an advance speed of 6.2 m/min). The Ti-6242 base material is characterized by a globular (α+β) microstructure. The heat input during laser beam welding led to the formation of a martensitic α’-phase fusion zone. The heat affected zone consisted of globular grains and acicular crystallites. These local transformations were connected with a change in the micro-texture, average grain size and β-phase content. Furthermore, the microhardness increased from 330 HV 0.3 to 450 HV 0.3 due to the martensitic transformation. The mechanical behavior of the laser beam welded Ti-6242 butt joint loaded in tension was determined by the properties of the Ti-6242 base material. The local increase in hardness provided a shielding effect that protected the Ti-6242 butt joint against mechanical damage.
Manufacturing of Aluminum Metal Matrix Cast Composites with Carbon Based Additives for Thermal Management Applications
Authors: Katz-Demyanetz Alexander , Squatrito Rosario , Todaro Ivan , Essel Shai , Zeidler Henning , Bamberger Menachem
Published: November 2016

This work focuses on the production of new high conductive carbon based MMC (Metal Matrix Composites) or co-cast components obtained by casting processes. These novel thermally conductive structures are designed to face modern heat management challenges in critical fields such as power micro-electronics, automotive and aerospace industries, renewable energy generation as well as highest performance combustion engines. The sought parts will be assembled by different heat conductive aluminum-carbon composites and for this reason different heat conductive MMCs have been studied. Their combination into once cast aluminum part may allow the part to meet applicative needs for heat management challenges.
The cast production routes as well as thermal behavior of the obtained materials has been studied by means of numerical (Finite Element Methods) approaches in order to determine the effective thermal conductivity in the different directions of heat dissipation. Some kinds of casting methods have been FEM simulated and then performed practically. TPG/aluminum interface microstructure has been studied.
Microstructure Evolution Induced by Sliding-Based Surface Thermomechanical Treatments - Application to Pure Copper
Authors: Kermouche G. , Jacquet G. , Courbon C. , Rech J. , Zhang Y.Y. , Chromik R.
Published: November 2016

In this paper, surface microstructural evolution induced by processes based on repeated sliding (friction) contact such as burnishing or machining is investigated. A set-up designed for simulating contact pressures and cutting speed occurring during machining is used to create a gradient of nanomicro-structure. It is composed of a top surface recrystallized layer and a sub-surface made of ultrafine grains over a depth larger than 100 μm. Induced-mechanical properties as well as resulting wear resistance are discussed. A conclusion is brought on the benefits of this new kind of sliding-based surface mechanical treatments (SMT).
The Effects of Ultrasonic Nanocrystal Surface Modification Technique Temperature on Microstructure and Wear of Alloy 600
Authors: Kim Jun Hyong , Amanov Auezhan , Pyun Young Sik
Published: November 2016

Alloy 600 (UNS N06600) is an austenitic nickel-based alloy with superior corrosion resistance and high-temperature endurance, which determines its widespread applications in aeronautical, aerospace, marine and nuclear industries. Particularly, a number of nuclear components used Alloy 600 as their structure materials due to their high corrosion resistance, high-temperature endurance and excellent fabricant characteristics. Many failures have occurred in Alloy 600 with various forms of environmental degradations during long-term operation. In this study, an ultrasonic nanocrystal surface modification (UNSM) technique was applied to Alloy 600 at a room and a high temperature of 500 OC. The effects of UNSM treatment temperature on the microstructure and wear behavior including a compressive residual stress were investigated. The hardness, compressive residual stress with respect to depth from the top surface were measured. Also, the wear behavior of UNSM-treated at a room and a high temperature Alloy 600 specimen was compared to that of the untreated specimen. The increase in wear resistance by UNSM technique was discussed in terms of increased hardness, refined grain size and induced compressive residual stress.
Effects of Die Steel on Die Soldering of Aluminum Alloy Die Casting
Authors: Kim Yu Mi , Choi Se Weon , Kim Young Chan , Hong Sung Kil , Kang Da Som , Moon Min Kook
Published: November 2016

This study carried out a die soldering test using both H13 and 1045 steel to investigate the different performances of these two substrate materials with regard to die soldering. Aluminum alloys with various amounts of silicon (0, 4.5, and 9 wt.%) were used to investigate the action of silicon in the soldering reaction, with the 0 wt.% material being commercial pure aluminum. Aluminum alloy samples of varying Si content were melted and held at 680oC and both H13 and 1045 steel were dipped for two hours in the melt. After the dipping test, the specimens were air cooled and analyzed using SEM and EPMA. The reaction layer of the H13 steel and the aluminum alloys were composed of Al3Fe (ɵ), Al5Fe2(η) and Al8Fe2Si (τ5) phase. The reaction layer between the 1045 steel and the aluminum melt was composed AlFe (ζ), Al5Fe2 (η), Al3Fe (ɵ), and Al8Fe2Si (τ5). The reaction layer thickness with the H13 substrate increased with the Si content of the aluminum; it deceased with increased Si content with the 1045 steel substrate.
On the Dynamic Superplasticity
Authors: Kitaeva Daria A. , Kodzhaspirov G.E. , Rudaev Yakov I.
Published: November 2016

Superplasticity is considered as a special state of the polycrystalline material plastically deformed at the low level of the stress with the retaining of the ultrafine-grained structure – structural superplasticity received at the previous stage or arised during hot deformation independently from the initial grain size – dynamic superplasticity. For realization of the dynamic superplasticity it has to substitute an initial structural condition of material another, allowed to realize a superplasticity. The mentioned above changes are caused by the conforms of the proper strain rates and structural (phase) transformations of the evolutionary type in the open nonequilibrium systems. It is proposed an approach applying to the modelling of the deformation processes at the superplastic flow of commercial aluminum alloys taking into account the boundary regions in the framework the theory of self-organization of dissipative structures. An examples of the theoretical and experimental data correlation are given.