bluuebunny/crossref_metadata_2025 huggingface dataset:
Alloy Design of Creep- and Oxidation-Resistant 9%Cr Steel for High Efficiency USC Power Plant
Authors: Abe Fujio
Published: January 2012

Ferritic heat resistant steels are strongly desired to expand their maximum use temperature up to 650°C for application to the next highest temperature components of highly efficient, low emission ultra-supercritical (USC) power plant with maximum steam temperature of 700 °C. This minimizes the requirement of expensive nickel base superalloys. Critical issues for the development of ferritic steels for 650 °C USC boilers are the improvement of oxidation resistance as well as long-term creep rupture strength, including welded joints. The optimized combination of boron addition and dispersion of nanometer-sized vanadium nitrides significantly improves long-term creep strength of 9% Cr steel and also exhibits no degradation in welded joints at 650 °C. The protective Cr2O3-rich scale forms on the surface of 9% Cr steel by pre-oxidation treatment in Ar gas, which significantly improves the oxidation resistance in steam at 650°C.
Effect of Rapid Solidification on Microstructural Features of Al-Cr Alloys
Authors: Tashlykova-Bushkevich Iya I. , Itoh Goroh
Published: January 2012

Microstructure of rapidly solidified (RS) pure Al and Al-0.8; 1.0 Cr alloys (at %) foils was examined with reference to near surface composition, solute/microstructure interactions, and surface topography. The hydrogen desorption from Al-Cr alloys was investigated in order to clarify effect of rapid solidification processing (RSP) on hydrogen trapping in specimens. It is suggested that hydrogen occupancy for vacancy traps in the alloys is decreased in contrast to that reported for pure Al foils and is related to the formation of vacancy-alloying element atom complexes.
Development of NiMnGa/Polymer Composite Materials
Authors: Hosoda Hideki , Inamura Tomonari
Published: January 2012

In this paper the recent development of NiMnGa-particles-embedded polymer-matrix magnetodriven composites achieved by our group is described. The NiMnGa single-crystal particles can be easily fabricated by mechanically crushing the polycrystalline ingots due to intrinsic intergranular brittleness. The elastic back stress from the matrix polymer induces the reverse reorientation of martensite variants after removing the magnetic field. However, the actuation strain observed was very small around 10ppm which was 1/1000 times lower than the calculated value. Some possible reasons for the disagreement are that the crystallographic orientation of NiMnGa particles is random distribution, lattice defects introduced during crushing suppress reorientation of martensite variants, and that the elastic restriction from the matrix polymer is higher than expected. Therefore, the martensite variant reorientation behavior of the NiMnGa/silicone composites has been investigated from the viewpoint of (1) volume fraction of matrix polymer, (2) elastic modulus of polymer and (3) direction of magnetic field applied. And also, the internal structures of the composites were directly evaluated by microfocused X-ray computed tomography (µ-CT).
Producing Aluminum Foam Sandwich Panel by Melt Drag Process
Authors: Nishida Shinichi , Tanaka Hiroto , Adachi M. , Motomura M.
Published: January 2012

Aluminum foam is porous material and it is superior property which is light weight , absorption sound, heat insulation and energy absorption than other materials. In present the panel of aluminum foam sandwich panel to use as structural materials is adhered with adhesive or wax for adhesion. The aim of this study is to clarify producing conditions to make sandwich panel by melt drag process. Melt drag process is single roll strip casting process. Producing aluminum alloy strip and adhering foam are at a time.
Effect of Liquid Hot Isostatic Pressing on Structure and Mechanical Properties of Aluminum Gravity Die Castings
Authors: Ivanova Elena , Tagirov Damir , Kaibyshev Rustam
Published: January 2012

Effect of liquid hot isostatic pressing (LHIP) on structure and mechanical properties of an A356.0 alloy was examined. Samples from this alloy were produced by gravity die castings. Part of these samples was subjected to homogenization annealing, and the other part was subjected to LHIP following homogenization annealing. All samples were water quenched from the temperature of prior homogenization annealing or LHIP and finally aged. It was shown that the LHIP processing leads to increase in yield stress, ultimate stress and total elongation. A significant increase in fatigue strength and decreased the scattering of fatigue data takes place too. This is caused by the fact that the fatigue crack initiation mostly occurs on lateral surfaces of the samples subjected to LHIP, whereas shrinkage voids in the non-hipped condition play a major role in crack initiation. In addition, crack propagation under fatigue occurs in samples subjected to LHIP in essentially ductile manner. Thus, LHIP eliminating shrinkage porosity enhances significantly mechanical properties and reliability of aluminum casting.
Progress and Issues in Thermomechanical Simulation: Experience in Tata Steel (Europe)
Authors: Howe A.A. , Parker S.V. , Beaverstock R. , van Haaften W.M.
Published: January 2012

Thermomechanical simulation serves to simulate industrial conditions under closer control and much more cheaply than through works trials, and also under ideal conditions (e.g. constant temperature and strain rate) more suitable for input to metallurgical models which can then be applied to real cases. It is remarkable how much effort in Industry and Academia, and how many conferences, are devoted to this issue. Moreover, many of the questions being addressed do not appear to change very much over the years [1]. The continuing stream of new rolled grades requires new experimental quantification and adjustment to models, because we do not as yet have a physically-based model powerful enough to extrapolate safely to substantially different compositions and process conditions. But that is only part of the story. Quantitatively sufficient simulation of the existing grade portfolio is a surprisingly complex, multi-facetted problem. An example is presented in Fig.1 [2] of the model in routine use for Tata Steel’s plate mill at Scunthorpe, UK. Many variables are involved in the prediction of the optimum rolling schedule in terms of productivity, plate geometry, and final properties, each of which will be associated with its own errors. Its configuration around the microstructural development during rolling brings in a range of variables which are very difficult to measure on plant, and are usually implied from laboratory studies. Extensive plant data exist but are seldom transferable to other mills owing to the individual set-up of each mill and its associated data measurement facilities. Similarly, great care has to be taken to avoid systematic differences between laboratory simulation, pilot rolling, and results on plant, owing to subtleties of the set conditions and accuracy of measurement. An overview of such experience in Tata Steel’s European plate and strip mills is given here.
Applications of Ceramic Nanoparticles in Nanomedicine
Authors: Ciofani Gianni , Danti Serena , Ricotti Leonardo , D’Alessandro Delfo , Moscato Stefania , Menciassi Arianna , Mattoli Virgilio
Published: January 2012

This paper reports on two examples of biomedical applications of ceramic nanoparticles. Thanks to their physical and chemical inertia, barium titanate nanoparticles and boron nitride nanotubes have been proved to have an optimal in vitro biocompatibility, even at high concentrations. Barium titanate nanoparticles-doxorubicin composites are successfully internalized by cancer cells, and allow for a considerable enhancement of drug up-take. Conversely, boron nitride nanotubes are explored as “nanotransducers”, thanks to their excellent piezoelectric properties. These two examples encourage further investigations and applications in biology and medicine of ceramic nanomaterials, that exhibit interesting advantages respect to traditional materials.
Control of Osteoblastic Cell Behavior by Surface Topography Introduced by Plastic Deformation of Ti Single Crystal with h.c.p. Structure
Authors: Matsugaki Aira , Aramoto Gento , Ishimoto Takuya , Nakano Takayoshi
Published: January 2012

Cells are known to sense the topographic features of the substrate and align along the direction of the surface pattern, and this is believed to be an important aspect in the formation and regeneration of anisotropic biological tissues. In this study, a unique and anisotropic stepped pattern was produced on single crystals of α-Ti with the h.c.p. lattice by plastic deformation in compression to demonstrate the effect of the pattern on cell behavior. Because the Schmid factor for the operative slip system of prismatic (100)[110] was set to be 0.5, the slip traces with an acute angle of 45° appeared on the surface. A smooth substrate without plastic deformation was used as a control. MC3T3-E1 osteoblastic cells were cultured on the substrate for 24 h, followed by observation of the morphology and alignment of the cells by Giemsa staining. On stepped substrates, cells aligned along the slip traces, and the filopodia of the aligned cells were found to extend parallel to the slip traces. The slip traces induced by plastic deformation of a single crystal was successfully proven to be a potent substrate to control the alignment of cells.
Strategy for Achieving High Strength in Al-Mg-Sc Alloys by Intense Plastic Straining
Authors: Kaibyshev Rustam , Mogucheva Anna , Dubyna Andrii
Published: January 2012

It is shown that implementation of high strains through equal-channel angular pressing (ECAP) and/or rolling into alloys belonging to Al-Mg-Sc-Zr system allows achieving high strength and satisfactory ductility. It was shown that strain hardening gives a main contribution to overall strength increment attributed to intense plastic straining; the role of grain size hardening is minor. However, extensive grain refinement is a necessary condition for retaining sufficient ductility in full-hardened condition for these materials.
Single Crystal Growth and its Microstructure in Co-Cr-Mo Alloys for Biomedical Applications
Authors: Nakano Takayoshi , Sasaki Keita , Hagihara Koji , Ishimoto Takuya , Fujii Yusuke , Serizawa Ai
Published: January 2012

Co-Cr-Mo based alloys have been widely employed as heat resistant materials and as biomaterials for implants because of their high strength and superior wear resistance. In general, the alloys exhibit a very complicated composition-dependent microstructure containing stacking faults and related mechanical properties. Thus, the essential properties must be clarified by using not only polycrystals but also single crystals. To our knowledge, single crystals and related properties have not been reported elsewhere. Thus, Co-Cr-Mo single crystals were grown and used to analyze the microstructure and the related properties. Single crystals with a composition Co-27 mass% Cr-6 mass% Mo alloy defined by ASTM F75 were grown by two single crystal apparatuses: the optical floating zone and the Bridgman methods. The single crystals with the smooth-surface shape were successfully obtained in the Bridgman method under an Ar gas atmosphere at a crystal growth rate of 5.0 or 2.5 mm/h. A portion of the crystals contain Al as Al2O3 precipitates from the crucible. Since the Al2O3 precipitate induces martensitic phase transformation from fcc (γ) phase to hcp (ε) phase, the single crystals were separated into two parts (a) containing Al2O3 precipitate and (b) in the absence of the clear precipitate. The microstructure was significantly altered by the martensitic phase transformation from the γ to ε phase induced by stress field or heating. In addition, variant formation of ε phase has a large influence on the mechanical functions of these Co-Cr-Mo alloys. Novel findings were preliminary obtained in the single crystals.
Collagen-Silk Fibroin Fibers: A Promising Scaffold for Vascular Tissue Engineering
Authors: Paternotte Estelle , Agostini de Moraes Mariana , Beppu Marisa Masumi , Mantovani Diego
Published: January 2012

Small caliber vascular replacement (<4 mm) still remains a challenge for medical and research teams, as no available vascular substitutes (VS) are suitable for small diameter bypass. Vascular engineering proposes new models of small diameter VS but rare are those that meet the biocompatibility and mechanical criteria. In this study, we developed a new scaffold made by the combination of two natural biomacromolecules: collagen and silk fibroin. The scaffold was further cellularised with porcine smooth muscle cells. First, the behavior of cells in the collagen-fibroin constructs was verified in order to evaluate the biocompatibility of the scaffold with the cells. Then, gel mass loss and cellular attachment, morphology, spreading and viability were analysed. The results showed an excellent interaction and biocompatibility between collagen, silk fibroin fibers and cells. Thus, the collagen-fibroin construct appears to be a very attractive material for vascular tissue engineering.
Synthesis and Characterization of Hydroxyapatite-Based Nanostructures: Nanoparticles, Nanoplates, Nanofibers and Nanoribbons
Authors: Rivera-Muñoz Eric M. , Velázquez-Castillo Rodrigo , Huirache-Acuña Rafael , Cabrera-Torres J.L. , Arenas-Alatorre Jesús
Published: January 2012

Material science is taking an increasing important role in bioengineering and biomedical sciences, aiming to develop new systems and materials capable of adapting to the highly demanding environment of a living organism. One of those materials, Hydroxyapatite (HAp), is the principal calcium orthophosphate present in the mineral phase of bone.
Collagen Based Materials for Biomedical Applications: Preparation and Properties
Authors: Sionkowska Alina
Published: January 2012

Collagen-based materials were prepared and their properties were studied. The shape of collagen materials was as follows: thin films, hydrogels, and sponges. Microstructure and mechanical properties of films and sponges were studied. The effect of cross-linking agents and the effect of synthetic polymer on the properties of collagen materials were studied and analyzed. Collagen-based materials can be considered as potential biomaterials in tissue engineering.
Fabrication of Injection Moulded 304L Stainless Steels Reinforced with Tungsten Carbide Particles
Authors: Chuankrerkkul Nutthita , Chakartnarodom Parinya
Published: January 2012

Powder injection moulding of 304L stainless steel - tungsten carbide (WC) composites were carried out in the present work. Two different WC particle i.e. WC having average size of 4.8 µm and 1.6 µm were used. Feedstock of powder loading up to 55 vol% were successfully prepared using binder composed mainly of polyethylene glycol (PEG) and a minor constituent of polymethylmethacrylate (PMMA). The mouldings were leached in water at temperatures of 40 °C and 60 °C from 30 minutes to 24 hours in order to study the effect of leaching conditions on the removal of the PEG. The remaining binder, PMMA, provided strength to the mouldings after leaching of the PEG and it could be removed by pyrolysis during ramping up to the sintering temperature. Specimens were sintered under hydrogen atmosphere at 1250 °C for 1 hour. Sintered components were subjected to testing and characterisation. Scanning electron microscope was used to observe microstructure of specimens after moulding, leaching and sintering. It was found that the hardness of the sintered specimens increased with either increasing the amount of the powder loading in the feedstock or reducing the average size of WC in the powder mixture. In addition, the water leaching of the PEG linearly correlates with the natural log of time and the equation predicts that PEG will be removed completely in 11.24 ± 1.31 hours which corresponds with the experiment result that PEG completely removed in 12 hours.
Forming Potential of Steel/Polymer/Steel Sandwich Composites with Local Plate Inserts
Authors: Palkowski Heinz , Sokolova Olga , Carradò Adele
Published: January 2012

High-performance metal/polymer/metal hybrid sandwich composites are attractive materials for lightweight constructions in automotive, aerospace and naval engineering world-wide. Due to the excellent combination of mechanical, thermal and elastic properties and, as a result of high forming potential, they can be used in areas of high vibration, where high damping properties of the polymer are demanded and at the same time high strength and stiffness are given by the metal. Disadvantages can be given in case of mechanical or thermal joining of these polymer-based sandwiches because of the elastic behaviour as well as low melting temperature of the polymer. Local metal plate insertions in the soft core at the place of joining can be a solution for such kind of problems. But forming behaviour of sandwich materials with and without local inlays differs strongly. Sandwich composites of that type were produced by roll-bonding. Their quality and their position were controlled by Lockin thermography. The forming behaviour of sandwiches with different geometry, size, type and the position of the inlays was tested by deep drawing and bending and analysed with the help of digital photogrammetry and compared to experimentally obtained mechanical properties. As a result, the local inlays, as well as their geometry, size and type strongly influence the forming limit conditions. The differences in flow behaviour of non-reinforced and reinforced sandwich regions after deep drawing and bending will be presented, as well as the influence of the position of the inlays.
Fabrication of Bulk Functionally-Graded Syntactic Foams for Impact Energy Absorption
Authors: Adachi Tadaharu , Higuchi Masahiro
Published: January 2012

Function of functionally-graded (FG) foams as energy absorption material for impact was discussed on the basis of theoretical analysis, and fabrication process of the foams was proposed in the paper. The FG foams were found to be useful as impact absorber due to progressively local fracture or cushion in the theoretical analysis. Next the fabrication process of the FG foams was suggested. The graded dispersion of the micro-balloons was conducted before curing the matrix resin in the process. The density distributions in the FG foams were confirmed to be predicted by the numerical analysis on the basis of floating the micro-balloons. Finally, compression tests were carried out to evaluate mechanical properties.
Comparison of Experimental and Numerical Results for the Quasi-Static and Dynamic Tensile Behaviour of a Commercial Ti6Al4V Alloy as a Function of Initial Crystallographic Texture
Authors: Coghe Frederik , Tirry Wim , Peirs Jan , Verleysen Patricia , Dalgaard E. , Wanjara Priti , Rabet Luc , van Houtte Paul
Published: January 2012

Quasi-static tensile tests and high strain rate split Hopkinson bar tensile experiments were used to mechanically characterize a commercially available Ti6Al4V alloy. The material was tested along different directions as to assess the influence of the initial crystallographic texture on the mechanical behaviour. In order to circumvent the problem of the limited thickness of the base material, special usage was made of the Linear Friction Welding technique. The results of the experiments were afterwards compared to the numerical results of a crystal plasticity code based on the viscoplastic self-consistent approach, taking into account twinning as an active deformation mode.
Controlling of Distribution of Mechanical Properties in Functionally-Graded Syntactic Foams for Impact Energy Absorption
Authors: Higuchi Masahiro , Adachi Tadaharu , Yokochi Yuto , Fujimoto Kenta
Published: January 2012

In the study, novel fabrication processes of functionally-graded (FG) syntactic foams were developed to control distribution of the mechanical properties in the FG foams for highly impact energy absorption. In order to control mechanical properties, the density distributions in FG foams were graded by floating phenomenon of the light-weight micro-balloons in matrix resin during curing process. The density distribution in the foam could be controlled by adjusting the average volume fraction and the turning procedure of the mold before grading the micro-balloons in the foam. The compression tests of the fabricated FG foams suggested that the foams had high absorption of impact energy since the foams collapsed progressively due to the grading of the density distribution.
Phase Transformation of Powdered Material by Using Metal Jet
Authors: Kira Akio , Tomoshige Ryuichi , Hokamoto Kazuyuki , Fujita Masahiro
Published: January 2012

The various techniques of phase transformation of the material have been proposed by many researchers. We have developed several devices to generate the ultrahigh pressure by using high explosive. One of them uses metal jets. It is expected that the ultrahigh pressure occurs by the head-on collision between metal jets, because the velocity of the metal jet is very high. By mixing a powdered material with metal jets, the pressure of the material becomes high. The purpose of this study is to transform the phase of the powdered material by using this high pressure. The powders of the graphite and hBN were applied. The synthesis to the diamond and cBN was confirmed by X-ray diffraction (XRD). In this paper, the mechanism of the generation of the ultrahigh pressure is explained and the results of the observation of the powder by using scanning transmission electron microscope (STEM) are reported.
Underwater Explosive Welding Using Detonating Code
Authors: Mori Akihisa , Fukushima Ayumu , Shiramoto Kazumasa , Fujita Masahiro
Published: January 2012

Detonating code, which is a flexible code with an explosive core, is normally used to transmit the ignition of explosives with high detonation velocity 6 km/s. Therefore it is difficult to use detonating code for the explosive welding of common metals toward the detonating direction since the welding velocity exceeds the sound velocity of metals. Hence, an explosive welding method using underwater shock wave generated by the detonation of detonating code was tried. In the present investigation, the details of the experimental setup and results are reported. And the welding conditions are discussed through numerical simulation. From these results it is observed that the above technique is suitable to weld thin metal plates with relatively less explosives.
Dynamic Tensile Properties of Magnesium Nanocomposite
Authors: Guo Y.B. , Shim V.P.W. , Tan B. W. F.
Published: January 2012

In this study, a Mg-6wt%Al alloy and its composite containing 0.22vol% Al2O3 nanoparticles are fabricated using a disintegrated melt deposition technique, and samples are subjected to quasi-static and dynamic tension. Compared to quasi-static loading, both materials exhibit significantly higher yield stresses and tensile strengths, much better ductility, and thus a higher energy absorption capacity under dynamic tension. In terms of nanoparticle addition, its influence on the mechanical properties are not notable; enhancement of the elastic modulus, yield stress and tensile strength are negligible, and there is a small reduction in ductility. The tensile behaviour obtained in this investigation was compared with results of previous compression tests, and significant tension-compression asymmetry in the response is observed. The tensile yield stress is noticeably larger than that in compression, and the profile of the stress-strain curve for tension differs from that for compression – it is convex upwards for tension, but concave upwards for compression. A possible reason for this asymmetry is the occurrence of twinning in compression and its absence in tension.
Impact Compressive Failure of a Unidirectional Carbon/Epoxy Laminated Composite in Three Principal Material Directions
Authors: Yokoyama Takashi
Published: January 2012

The impact compressive failure behavior of a unidirectional T700/2521 carbon/epoxy laminated composite in three principal material directions or fiber (1-), in-plane transverse (2-) and through-thickness (3-) directions is investigated on the conventional split Hopkinson pressure bar (SHPB). Cubic and rectangular block specimens with identical square cross section are machined from an about 10 mm thick composite laminate. The uniaxial compressive stress-strain curves up to failure at quasi-static and intermediate strain rates are measured on an Instron testing machine. It is shown that the ultimate compressive strength and strain exhibit no strain-rate effect in the 1-direction, but a slight strain-rate effect in the 2-and 3-direction over a range of strain rates from10-3 to 103/s.
Sintered Lamellar Soft Magnetic Composites: Shaping and Magnetic Properties
Authors: Bernier Fabrice , Lemieux Patrick , Isac Mihaiela , Guthrie Roderick I.L. , Thomas Yannig
Published: January 2012

Sintered lamellar soft magnetic composite (SL-SMC) is a promising material for power frequency applications and for all types of electric motors, including induction motors. Alumina coated Fe-3%Si particles cut from steel sheets offer both the advantages of standard laminated steel products, and of soft magnetic composites (SMC). As SMC’s, this material can be shaped using standard near-net shape powder metallurgy (P/M) techniques, which represents a big advantage over coated laminated steel assemblies. Indeed, the P/M process, as compared to laminated steel assemblies, gives access to better design and improved motor assembling techniques, at lower production costs, by limiting machining and stamping. The unique structure of the SL-SMC offers better DC magnetic properties than standard SMC’s, allowing them to cover a larger range of applications. However, there still remains work to be done in developing this new technology to its full potential, using low cost industrial techniques. This paper is divided into two main parts. The first is dedicated towards assessing the possibility of producing SL-SMC parts using an automatic industrial compaction press. The impact of two different lubrication systems, admixed solid lubricants and die wall lubrication, on the density and green strength of the motor parts, will be determined. Also, the process capability will be evaluated on the basis of “part to part” stability. The second section of this study will determine the impact of different processing parameters on the mechanical and magnetic properties of the Fe-3%Si alloy. Results show that by carefully controlling heat treatment, very high maximum induction, low magnetic loss and good mechanical property, can all be reached in fabricated parts.
Influence of Laser Processing on Polycrystalline Silicon Surface
Authors: Dobrzański Leszek Adam , Drygała Aleksandra
Published: January 2012

This paper presents technology of multicrystalline silicon solar cells with laser texturisation step. The texturing of polycrystalline silicon surface using Nd:YAG laser makes it possible to increase absorption of the incident solar radiation. Moreover, the additional technological operation consisting in etching in 20 % KOH solution at temperature of 80°C was introduced into technology of the photovoltaic cells manufactured from laser textured wafers allows to remove laser induced defects but cause the texture to flatten out reducing it optical effectiveness. This paper demonstrates, that laser processing is very promising technique for texturing multicrystaline silicon independent on grains crystallographic orientation compared to conventional texturing methods in technology of solar cells.
Effect of Boron on Microstructure and Impact Toughness of a 10%Cr Martensitic Steel
Authors: Dudova Nadezhda , Kaibyshev Rustam
Published: January 2012

It was shown that in a 10% Cr martensitic steel enriched by boron this element tends to segregate within M23C6 carbides having the film-like shape and precipitated on the boundaries of prior austenite grains (PAG), mainly. It leads to a low value of Charpy V-notch impact toughness of 6 J/cm2. These carbides are highly resistant against the spheroidizing. Only the tempering at 770°C leads to the final formation of M23C6 carbides having the equiaxed shape. Concurrently, this tempering strongly decreases boron segregation. As a result, the 10% Cr martensitic steel exhibits a high value of Charpy V-notch impact toughness of 260 J/cm2.
Accelerated Microstructure Transformation Caused by Thermal-Mechanical Fatigue
Authors: Mandziej Stan T.
Published: January 2012

Thermal mechanical fatigue (TMF) was found to accelerate microstructure transformation in martensitic-bainitic Cr-Mo-V creep-resisting steels used in power generation. Particular role in this acceleration has been ascribed as being due to configurations of dislocations generated in the compression part of the TMF cycle, which dislocations in the tensile part of the cycle appeared to assist precipitation processes while important role in this acceleration is due to Bauschinger effect. Based on this finding an accelerated creep test (ACT) on Gleeble thermal mechanical simulator was developed to gain in a short time of less than 30 hours the microstructures and properties of steels and welds similar to these appearing after the long-term exposure in power plants. Investigations by scanning electron microscopy and transmission electron microscopy confirmed similarity of microstructure transformation after the ACT with this occurring after the multi-year real creep in power generating installations, in particular in these where premature failures occurred.
Fracture Resistance in GFRP-BMC Composites Induced by Sub-Millimeter Length Fiber Dispersion
Authors: Faudree Michael C. , Nishi Yoshitake
Published: January 2012

Based on previous results of both an increase of nearly 40% in static tensile strain by shortening fiber length from commercial 6.4 mm to 0.44 mm in an unsaturated polyester/styrene-butadiene GFRP-BMC composite containing 20 mass% short E-glass fibers and their acoustic emissions (AE), the fracture resistance mechanics of sub-mm length fiber dispersion reinforcement is proposed. Since the 40% strain increase acts to improve strength and toughness, the mechanics is useful. This paper aims to present the mechanism of strain-driven improvement where microcracks are prevented from propagating beyond the critical crack size (2ac) for thermoset polymers, resulting in an increased and more dispersed total microcrack surface area as recorded by AE raising fracture strain.
Brittle Crack Propagation/Arrest Behavior in T-Joint Structure of Heavy Gauge Steel Plates
Authors: Handa Tsunehisa , Nishimura Kimihiro , Shiomi Hiroshi , Tsuyama Seishi
Published: January 2012

Brittle crack arrestability is extremely important in welded joints of heavy gauge steel plates used in large container ships. Recently, much attention has been focused on potential crack propagation along welds using large heat input. This paper examines the application of a T-joint to the strength deck structure of container ships to enhance crack arrestability. The crack arrest toughness, Kca, for crack arrest was varied. The ESSO test of T-joint components showed that brittle crack was arrested at the T-joint if the steel plate used for the flange had a high Kca value in the range from 4900 to 7300N/mm3/2. FE-analysis of the stress intensity factor K indicated that brittle crack propagation was arrested under the condition that the K-value at the running crack tip was less than the Kca of the material. In the T-joint, it was noted that the K-value around the area of the deepest point of the crack decreased and was finally less than the Kca of the flange plate when the brittle crack penetrated suddenly into the flange plate to a 10mm depth. This phenomenon shows the advantage of using a T-joint for brittle crack arrest in the flange plates of strength deck structures.
Quality of Interfaces in Cu/Al Dissimilar Friction-Stirred Welds
Authors: Avettand-Fènoël Marie Noëlle , Taillard Roland , Ji Gang
Published: January 2012

The current work focuses on the particular case of dissimilar 6082 Al alloy/pure copper butt-friction stirred joints. It takes advantage of voluntarily non optimized welding conditions in order to test the potential of an original approach of identification of the welding defects by means of a single tensile test. The sequence and mechanism of the fracture events arise from their localization on the fracture surfaces thanks to strain maps obtained by digital image correlation. This technique of flaws identification is proved to be particularly efficient at least with the present highly damaged welds.
Effect of Processing Parameters on Superplastic and Corrosion Behavior of Aluminum Alloy Friction Stir Processed
Authors: Burgueño A. , Svoboda Hernán Gabriel , Svoboda H.
Published: January 2012

Friction Stir Processing (FSP) is a variant of Friction Stir Welding, and can be used to modify the materials microstructure to functionalize it. Superplastic forming is a technological process used to produce components with very complex shapes. In the last two decades it has been a topic of major development. In Fine Structure Superplasticity (FSSP), the initial grain size exerts a strong influence on the superplastic strain rate and temperatures. Refining grain size (GS) the parameters (temperature and strain rate) of superplastic forming could be optimized. Thermal stability is also an important factor to obtain superplasticity. FSP is used to refine GS, but the optimum processing parameters are still under study over different materials. Corrosion resistance can be affected by FSP too, but the information about it is scarce. In the present study, 7075-T651 aluminium alloy was friction stir processed under different conditions in order to improve superplastic behavior. Tool profile, rotation rate and traverse speed were analyzed. Microstructures with <4 μm grain size were obtained. The maximum superplastic elongations, in a range of 740 to 900%, at 400°C were obtained at 1x10-2s-1 strain rate. The results were discussed in terms of constitutive equations and microstructure evolution. Localized corrosion potentials were obtained. Localized corrosion resistance was affected by friction stir processing.
Microstructure and Mechanical Properties of FSWed Aluminum Extrusion with Bobbin Tools
Authors: Okamoto K. , Sato A. , Park Seung Hwan C. , Hirano Satoshi
Published: January 2012

Bobbin FSW technique is assessed in terms of process productivity and robustness considering the metallurgical and mechanical qualities of the joint. Several different designed bobbin tools were applied to aluminium A6xxx alloy extrusions, at feed rate of 400-1000mm/min with tool rotation speed of 600-1000rpm. In case of A6068-T6, a joint efficiency of 68% was achieved at 600mm/min, which is almost equivalent to the productivity and quality of the conventional FSWed joints, hence the potential of bobbin FSW technique was suggested. The bobbin tool design was further optimized considering the practical process robustness to the part fit issue, and defect free welds have been achieved for the joints with a set gap up to 1mm. However, the oxide remnant, so called “lazy S” was observed in a joint made with an inadequate designed tool, which significantly deteriorates the mechanical properties.
Underwater Welding of Duplex Stainless Steel
Authors: Łabanowski Jerzy , Fydrych Dariusz , Rogalski Grzegorz , Samson Krzysztof
Published: January 2012

The present work was conducted to assess the weldability of duplex stainless steel at underwater conditions. Interest of underwater welding of this steel grade is connected with necessity of preparing welding repair technologies for subsea pipelines widely used in offshore oil and gas industry. The GMA local cavity welding method was used in the investigations. Welded beads were performed underwater at 0.5 m depth and in the air. Metallographic examinations of welds, ferrite content assessment in microstructure and hardness test were performed. The good weldability at underwater conditions of duplex stainless with the use of GMA local cavity method was confirmed.
Degradation of Gel-Coat Layer in Glass/Polyester Laminate in Seawater Environment
Authors: Landowski M. , Budzik M. , Imielińska K.
Published: January 2012

Glass/polyester laminate coated with gelcoat layer of different thickness 0,5; 1,5; 3 mm was studied in terms of blistering behaviour and water sorption in hot water environment. Blistering was found to be accelerated for thin (0,5 mm) gel-coat layer compared to the thick (1,5; 3 mm), however no significant difference in blistering behaviour was observed between the laminates with gel-coat thickness 1,5 and 3 mm which may suggest that increasing the gel-coat thickness is effective only to a certain thickness limit. Microscopic studies demonstrated that blistering behaviour was related to the formation of subsurface cracks – longer and less densely distributed in thin gel-coat layers in contrast to numerous small cracks formed in the thick gel-coats.
Effect of Crystallization Process at Cryogenic Conditions on the Functional Properties of the SUPERSTON Alloy Used in Production the Ship’s Propellers
Authors: Majkowska Beata , Serbiński Waldemar
Published: January 2012

The purpose of this paper is to show results of laser treatment at cryogenic conditions of the SUPERSTON alloy used for ship’s propellers. That modification process ought to bring beneficial changes of microstructure and residual stresses in the surface layer. During the laser remelting at cryogenic conditions the microstructure changes significantly. This is related to synergistic effects of the solidification rate, phase transformations in the solid state and laser treatment parameters. That crystallization process had influence on functional properties such as corrosion and cavitation resistance of the SUPERSTON alloy which were tested during researches.
Numerical Modeling of Magnetorheological Elastomers Microstructure Behavior under Magnetic Field
Authors: Miedzińska Danuta , Slawinski Grzegorz , Niezgoda Tadeusz , Boczkowska Anna
Published: January 2012

Magnetorheological elastomers (MREs) are a class of so called “smart materials” which rheological and mechanical properties can be reversibly and rapidly controlled by an external magnetic field. MREs have attracted increasing attention and obtained broad application prospects recently. They can be used in valves, dumpers, brakes or sensors constructions. In the paper, the numerical models of a magnetorheological elastomers microstructure are presented. The influence of the applied magnetic field during the curing process of elastomer is taken into consideration in each model. The developed structures are built of the hyper elastic material which surrounds the iron particles. The models are first loaded with the external compression force and then with the internal forces simulating the influence of the applied magnetic field. The results of the numerical analyses are shown as the displacement, stress and strain distributions in each model. The influence of the MRE microstructure on the strength behavior of the researched material is strictly visible as the non-homogeneity in the described distributions.
Wear and Corrosion Characteristics of the Layers Type (Mn-P) Formed on Aluminium Alloys
Authors: Serbiński Waldemar , Wierzchoń Tadeusz
Published: January 2012

Aluminium alloys are the materials of choice when high-strenght-to-weight rations are required in structural components, and used widely in the automotive and aerospace industries. As an example, the use of an aluminium components in the automobile industry has greatly increased due to weight savings and resultant fuel economy improvements. There are many methods of surface consolidation of an aluminium alloys. This work presents the hybrid creation method of the newly layers type (Mn-P) on the AlSi13Mg1CuNi alloy, its microstructure, hardness, chemical and phase compositions as well as wear and corrosion resistance. Growth the wear resistance of an aluminium alloy coated with the layer type (Mn-P) is visable. The corrosion characteristics of these layers are also considered.
FEM Analysis of Lower Premolar Root Canal Filling
Authors: Bojar Witold , Walke Witold
Published: January 2012

Materials utilizing dentin adhesive technology were developed to provide more effective seal of a root canal. The combined use of new bondable root filling materials and self-adhesive sealers may increase the fracture resistance of filled canals. The null hypothesis of a positive influence on tooth biomechanics by a modern root canal filling material was tested in this study. In order to determine the strength characteristics of the analyzed endodontically treated human tooth the FEM (finite element method) was applied. Lower premolar was used to create a three dimensional model. Its canal was obturated using vertical compaction technique, gutta-percha and resin sealer, access opening was filled with composite resins. Strain analysis of the several elements of the tooth restoration does not allow attributing positive influence of contemporary obturating materials on mechanical properties of root canal dentin. Hypothetically, such an influence would have a filling material with comparable to dentin modulus of elasticity and flexural strength. It was also stated that loading the tooth with 250 N had an effect on increasing the tensions on the interface between filling material – sealer – canal wall. The stresses exceeded 4 MPa, reaching in extreme areas 10 MPa, what practically outweigh adhesion strength of modern root canal sealers. This phenomenon may provoke detachment of a filling from canal walls and therefore led to bacterial leakage. Results of this biomechanical analysis of the endodontically treated human premolar are valuable for a proper evaluation of mechanical properties of modern endodontic filling materials.
Positive Effect of Hydrogen Treatment in Titanium Ti-6Al-4V Alloy
Authors: Sozańska Maria
Published: January 2012

Positive nature of the effects of hydrogen on the properties of titanium alloys is manifested in the high temperature hydrogen treatment (HTM - Hydrogen Treatment of Materials), where hydrogen is temporary alloying component. This is possible because of the high values ​​of diffusion coefficients can be easily introduced into the titanium and it just as easily removed. Titanium and its alloys exhibit a high affinity for hydrogen absorption capacity, about 60% at. hydrogen at 600 °C. The hydrogen in titanium alloy is present in the form – an interstitial solution or titanium hydride. Since the specific volume of titanium hydride is about 13 ÷ 17% higher compared to α phase, it is high stress in the crystal lattice of this phase leads to local plastic deformation and large deformation phase. The paper presents the results of the possibilities of hydrogen using as a temporary alloying element in Ti-6Al-4V alloy. Treatment of hydrogen alloy consisted of three stages: hydrogenation in hydrogen gas atmosphere at 650 °C, a cyclic hydrogen-treatment (3 cycles 650 °C or 950 °C to 250 °C) and a dehydrogenation in vacuum (550 °C). It was shown that hydrogen affects appreciably changes the microstructure of surface layer of the tested titanium alloy. The aim of this study is thus to determine the effect of hydrogen on the two-phase microstructure, hardness, and corrosion resistance of the titanium alloy Ti-6Al-4V due to high-temperature hydrogen treatment.
Evaluation of Hydrogen Degradation by In Situ Ultrasonic Testing
Authors: Szwed Maciej , Lublińska Krystyna , Wielgat Marcin , Zagórski Andrzej , Spychalski Wojciech , Kurzydlowski Krzysztof J.
Published: January 2012

In this paper, the results are presented of the ultrasonic investigations of hydrogen degradation of 09G2S carbon steel. Samples of the steel were hydrogen charged with simultaneous registration of the ultrasonic signal. The results of ultrasonic investigations were verified by Light Microscopy (LM), Scanning Electron Microscopy (SEM) and X-ray microanalysis technique (EDS). It was shown that the in-situ ultrasonic flaw detection can be used to monitor the early stages of hydrogen degradation, i.e. the formation of microcracks caused by hydrogen trapping at nonmetallic inclusions and hydrogen blistering.
Effects of Laser Remelting at Cryogenic Conditions on Microstructure and Wear Resistance of the Ti6Al4V Alloy Applied in Medicine
Authors: Zieliński A. , Jażdżewska M. , Łubiński J. , Serbiński Waldemar
Published: January 2012

The titanium and its alloys can be subjected to surface treatment, including laser treatment. In this work a new laser treatment at cryogenic conditions of Ti6Al4V alloy has been described. The work has been aimed at establishing whether such surface treatment could be suitable for implants working under wear in biological corrosive environment. The remelting has been made with the use of CO2 continuous work laser at laser power between 3 and 6 kW, at scan rate 0.5 and 1 m/s. The microstructure, surface topography, hardness, microhardness and wear linear rate and mass loss under tribological tests made in Ringer`s solution have been made. The results have shown that despite the surface cracking the tribological properties in simulated body fluid have been substantially improved.
Indoor Atmospheric Degradation of Historical Metal Objects Studied by Spectroscopic Techniques
Authors: Żmuda–Trzebiatowska Iwona , Fietkiewicz Anna , Sliwinski G.
Published: January 2012

The surface layers resulting from prolonged exposure to the indoor environment and the bulk material of metal artifacts from the collection of National Museum in Gdansk are studied by means of spectroscopic techniques. The composition of the surface layers of the forged iron box lid covered with polychrome (XVI c.), and of the bronze female nude sculpture (antiquity) is obtained from the XRF and µ-Raman spectra. The elemental composition is confirmed by the LIP (Laser Induced Plasma) spectroscopic measurements. The quasi-nondestructive LIP technique applied for stratigraphic sampling performed with an accuracy of ca 2 µm across the multilayer surface coverage reveals such elements as C, Ba and Na in the uppermost layer. From coincidence of the XRF, Raman and LIP data the presence of surface contaminant CaCO3, the corrosion product FeO(OH) and patina Cu2 (OH)3Cl are concluded. It is shown that the complementary spectroscopic analysis allows for the in-depth study of the environmental impact on historical objects and delivers indications for the appropriate strategy of the planned conservation activities. Moreover, from the data collected from the technologies applied in the past, origin, provenance and routing of the artifacts can be concluded.
Modelling of the Heat Flux Density Distribution for Laser Beam Welding
Authors: Marmołowski A. , Kiełczyński W.
Published: January 2012

Great interest of the laser beam welding in industry is a new theoretical task, making planning the welding procedure specification and the quality control of welded joints easier. Estimating and calculating the dimensions of a weld pool and temperature distribution near weld mainly concern heat source modelling. In the presented work calculations of welding pool shape and thermal field for cylindrical-powered-normally model of heat source have been presented. Parameters of the model of heat source and weld pool geometry were determined using analytical-numerical calculations. The results of numerical calculations were compared with the experimental data for butt joint made by CO2 laser beam. Comparable results have been observed. Practical recommendations for assumptions of model parameters - the flux density energy distribution of the heat source in case of calculations of the thermal field in the vicinity of a weld pool are given.