bluuebunny/crossref_metadata_2025 huggingface dataset:
Influence of Surface Roughness on the Corrosion Behaviors of DP590 Steel
Authors: Fang Bai You
Published: January 2021

The influence of surface topography on the corrosion behaviors of DP590 steel was studied by damp heat tests and electrochemical measurements in this paper. Results show that the corrosion behaviors of DP590 steel cannot be evaluated by using average surface roughness (Sa) due to the little difference of surface roughness. Reduced valley depth (Svk) showed a good correlation with corrosion resistance in the potentialdynamic polarization test, and the greater Svk, the better the corrosion resistance. Furthermore, DP590 sample with higher proportion of peak on the surface tended to have more corrosion points during the damp heat test since peaks were electrochemically active.
Hot Stamped Aluminium for Crash-Resistant Automobile Safety Cage Applications
Authors: Pujante Jaume , Frómeta David , Garcia-Llamas Eduard , Gimenez Maria , Casellas Daniel
Published: January 2021

Hot stamping, also known as press hardening in the context of sheet steel, has steadily gained relevance in the automotive industry, starting off as a specialist application and turning into a staple technique in the production of safety cage products in little more than a decade. However, despite the weight reduction offered by martensitic steels, further improvement could be obtained by substituting these components by high-performance aluminium. In this regard, the very same process of hot stamping could be employed to attain the required combination of shape complexity and mechanical properties at a reasonable cost for mass-market application, if the limitations imposed by cycle time and process window could be overcome. In this work, the feasibility of hot stamping of 6000-series aluminium alloy sheet is studied, first in dilatometry experiments and later in semi-industrial conditions in a pilot facility. A cycle time shortening strategy is employed, and compared to the conventional thermal cycle in terms of implementation and obtained results. In addition to basic characterization, aluminium thus processed is studied in terms of fracture toughness, in order to obtain data relevant to crashworthiness that can be readily compared with alternative materials.
Tailored Liquid Phases for Enhanced Sintering of Advanced PM - Steels
Authors: Geroldinger Stefan , de Oro Calderon Raquel , Gierl-Mayer Christian , Danninger Herbert
Published: January 2021

The application of “masteralloys” as alloying carriers in Powder Metallurgy (PM) steels enables the introduction of highly oxygen‑sensitive alloying elements for advanced PM‑steels, by using a tailored liquid phase. The characteristics of the liquid and its interaction with the iron base powder are determining factors for final microstructure and dimensional behaviour. In this study, theoretical calculations and experimental findings are presented for the masteralloy systems Fe_Mn_Si_C, Fe_Cr_Si_C and Fe_Mn_Cr_Si_C. Lowered melting temperatures and narrow melting temperature intervals could be achieved. The interaction between Fe base material and the masteralloys was studied by infiltration and DTA experiments. It was found that by adjusting the C and Si content in the masteralloy, liquids with widely varying properties could be obtained. This might be a key for tailoring microstructures, properties and dimensional stability of advanced PM‑steels.
Thermal Barrier Coatings for Molybdenum Produced Using Nanopowders
Authors: Góral Marek , Kubaszek Tadeusz , Drajewicz Marcin , Borowski Przemyslaw
Published: January 2021

The molybdenum is one of the most important refractory metals used in aerospace industry. The main disadvantage of Mo is low oxidation resistance at elevated temperature and the using of protective coatings is necessary. In present article the new types of protective coatings produced by slurry method were developed. The slurries contained Al nanopowder and Si powder as well as non-organic binder (H2CrO4 and water). After immersion and drying the samples with slurries were heat treated at 1000°C in Ar atmosphere. The thickness of obtained coatings was in range 10-20 μm. The presences of phases form Mo-Al as well Mo-Si systems was analyzed using scanning electron microscopy. The developed coatings were used as a bond coat for ceramic layer produced by plasma spray physical vapour deposition method (PS-PVD). In this process the columnar ceramic layer contains yttria stabilized zirconia (YSZ) was obtained wit thickness above 100 μm. The obtained results showed that it is possible to obtain TBC coating on molybdenum contained Al-Si bond coat and outer YSZ ceramic layer. The proposed coating can be used in aerospace applications.
Increasing Hardenability and Hardness of Quenching and Tempering Alloys by Substituting Chromium with Manganese
Authors: Gramlich Alexander , Pape Fabian , Heßling Götz , Bleck Wolfgang
Published: January 2021

This study investigates the influence of the substitution of chromium (-0.8 wt.−%) by manganese (+1.3 wt.−%) in a standard quench and tempering steel and the predictability of property changes through simple simulations, only dependent on the chemical composition. The substitution of chromium by manganese leads to an increased hardness (+50 HV10) and a reduction of the critical cooling speed from 19 K s−1 for the reference alloys to 9 K s−1 for the new alloy and a nearly constant hardness of (600 HV10) after Jominy-test. The commercial software JMATPRO is used to simulate and predict key properties for the industrial production. It is shown that a successful simulation of phase transformation temperatures and the general directions of change can be predicted, but more complex properties like critical cooling rates or hardenability need more sophisticated methods.
Brazing of Stainless Steel Using Electrolytic Ni-P Plating Film and Investigation of Corrosion Behavior
Authors: Hashimoto Anna , Liu Shu Bin , Shohji Ikuo , Kobayashi Tatsuya , Hirohashi Junichiro , Wake Tsunehito , Arai Susumu , Kamakoshi Yuichiro
Published: January 2021

Electrodeposited Ni-11 mass%P alloy plating film was fabricated on the surface of stainless steel SUS304 to conduct brazing of SUS304 plates for a heat exchanger. Brazing of SUS304 plates with electrodeposited Ni-11P layers was carried out using a hydrogen reducing furnace. The microstructure and joint strength of the brazed joint were also investigated. From the result of the microstructural observation of the cross section of the joint, it was found that the brazing filler metal is homogeneously distributed without defects such as voids between the SUS304 plates. The results of electrochemical measurements showed that the P-concentrated phase in the Ni-11P alloy is preferentially dissolved in NaCl aqueous solution.
Micromechanical Simulation Approach of Dual Phase Steel Artificial Microstructure Using Random Field Model
Authors: Heddar Mohamed Imad Eddine , Matougui Nadjoua , Mehdi Brahim
Published: January 2021

In this study, a random field (RF) model with a Gaussian kernel was applied to generate an artificial microstructure of dual phase (DP) steels. Micrographs obtained from Scanning Electron Microscopy (SEM) were analyzed using image processing software to extract the grain size and the volume fraction of each phase. Based on watershed (Ws) segmentation and quantitative analysis, the real and artificial microstructures were compared by analyzing grain features related the solidity, grain size and aspect ratio (the proportional relationship between its width and its height). Consequently, this approach allows to simulate the overall stress-strain behavior of the analyzed microstructures. As a result, it was shown that the strain localization starts to develop at the ferrite/martensite interface and that the RF model could replicate the micromechanical behavior of DP steels.
Orthotropic Behaviour of Magnesium AZ31 Sheet during Strain Localization
Authors: Henseler Thorsten , Ullmann Madlen , Prahl Ulrich
Published: January 2021

It is known that metallic materials are characterized by anisotropy of their mechanical properties, with this being attributed to the conditions during the manufacturing process. For sheet metals, this anisotropy occurs symmetrically to the three orthogonal axes of the rolling, transverse and normal direction. This characteristic is referred to as orthotropic behaviour and manifests itself, for example, in earing during cupping tests. Therefore, orthotropic yield criteria are highly relevant for the numerical simulation of sheet metal forming processes. The Lankford coefficient, also known as the r-value, is a good experimental measure for characterizing orthotropic ductile behaviour of sheets, and can easily aid in parameter identification for yield criteria such as the Hill approaches. In the present investigations, Lankford coefficients were determined as a function of local strain in uniaxial tensile tests through high-resolution digital image correlation. The sample direction was varied between 0°, 45° and 90° to the rolling direction and the test temperature varied from RT to 350 °C at three different strain rates (0.01-1 s-1). By means of a novel backward analysis, the measuring range for the Lankford coefficients was positioned exactly in the necking area. An increase in temperatures showed a decrease in the initial Lankford coefficient. The results showed non-constant Lankford coefficients and commence the course of a natural exponential function depending on the local strain. Regardless of strain rate, the results revealed that the Lankford coefficients (r-values) at 150 °C, 250 °C and 350 °C approaches a steady-state of r = 1.14 with strains greater than 50 %.
Effect of Compressive Residual Stress on Film Formed by Mechanochemical Multifunction Cavitation Processing
Authors: Ijiri Masataka , Kato Fumihiro , Maeda Daisaku , Shimonishi Daichi , Yoshimura Toshihiko
Published: January 2021

Recently, mechanochemical multifunction cavitation (MC-MFC) was developed to improve the corrosion resistance of the magnesium surface. MFC is a technology that combines water jet peening and ultrasound cavitation. MC-MFC is a technology that adds phosphoric acid to water. It can improve the corrosion resistance by forming a phosphate film on the Mg surface. Conventional anodic oxidation, plating, and chemical vapor deposition can improve corrosion resistance by forming a film on the Mg surface, but it is difficult to improve characteristics such as compressive residual stress on the surface. MFC-treated surfaces have previously imparted various properties such as imparting compressive residual stress necessary to improve the fatigue strength to Al alloys and Cr-Mo steels. In this study, the effect of film formed on MC-MFC processed surface on compressive residual stress was investigated.
Grain Refinement of Fe-X Alloys Fabricated by Laser Powder Bed Fusion
Authors: Ikehata Hideaki , Jägle Eric
Published: January 2021

Grain refinement tendency of pure Fe and Fe-X (X=5~10at%Al, 2~10at%Ti) alloys produced by laser powder bed fusion (LPBF) process was investigated. Pure Fe, Al, and Ti powders were dry mixed and cubic samples were built from the mixtures. The microstructure analysis revealed that (1) the microstructure of pure Fe consisted of equiaxed grains having an average diameter of 1.7 μm with fine iron oxide particles. (2) Fe-5 and 10at%Al alloys showed coarse columnar grains. (3) Fe-2at%Ti shows a mixture of fine equiaxed and columnar shape grains. (4) the microstructures of Fe-5at%Ti and 10at%Ti alloys are fully equiaxed, and grain refinement tendency was confirmed with increasing Ti content. Ti(N,O) oxi-nitrides are efficient in reducing the grain size because of the low lattice misfit with the ferrite matrix. Additionally, the effectiveness of Ti(N,O) particles as grain refiners was confirmed by building samples using TiN powder mixed with Fe-10at%Al and Fe-2at%Ti. While these alloys alone are coarse grained, a dispersion of Ti(N,O) particles achieved a fine-grained microstructure.
The Influence of Introduced Strains on the Exfoliation Corrosion Behavior of Mg-14mass%Li-1mass%Al Alloy
Authors: Ikoma Hayato , Morishige Taiki , Takenaka Toshihide
Published: January 2021

Mg-Li alloys have much better formability than traditional Mg alloys. However, the corrosion resistance of Mg-Li alloys are low due to Li addition and cold-worked Mg-Li alloys sustain exfoliation corrosion, which is serious problem for practical use of Mg-Li alloys [1]. According to our previous report, the elongated grains may be the cause of the exfoliation corrosion. In this study, the exfoliation corrosion behavior of Mg-14mass%Li-1mass%Al (LA141) alloy processed by equal channel angular extrusion (ECAE) is characterized to see the corrosion morphology of the samples introduced more grains than rolling. The specimens processed by rolling showed only elongated grains and the ones processed by ECAE (Route A) at 2 and 4 times showed elongated grains and partially equiaxial grains and in the samples fabricated by ECAE (Route Bc) at 2 and 4 times, equiaxial grains were found by optical microscopy. In corrosion examination, the specimens of rolling and ECAE (Route A) developed exfoliation corrosions and the samples of ECAE (Route Bc) didn’t sustain exfoliation corrosion. This results were consistent with our previous report. Then the corrosion behavior of rolled and ECAEed samples were focused. The evaluation of the time until crack initiation and the number of cracks were employed to see the corrosion morphology of the samples
Influence of Chromium and Niobium on the Press-Hardening Process of Multiphase Low-Alloy TRIP Steels
Authors: Jirková Hana , Vrtáček Jiří , Peković Michal , Janda Tomáš , Kučerová Ludmila
Published: January 2021

Press-hardening is an intensively developing forming technology which is mainly used for the production of car body parts. Because it is a hot forming technology, small forming forces can be utilized and, due to the lower spring-back effect, more accurate products are achieved. In car bodies, materials with high energy absorption and a sufficient hardening coefficient are mainly used in impacted parts. One of these materials is TRIP multiphase steels with different chemical composition. In these steels, it is possible to achieve an ultimate strength up to 1000 MPa with the ductility of 20-30%. In order to achieve the desired properties, it is necessary to select a suitable heat treatment that allows to achieve a multiphase structure. Phase transformations and mechanical properties are influenced by the use of suitable alloying elements. Three low-alloy, multiphase TRIP steels with different chemical compositions with a carbon content of 0.2% were chosen for the experimental program. The first steel was alloyed only with manganese and silicon, in the second niobium was added, and in the third the influence of chromium on increase of hardenability and strength was investigated. Press-hardening was performed in a heated forming tool. To describe the effect of the cooling rate, the forming was carried out in a tool at room temperature and after preheating to 425°C. The influence of holding time in the tool at 425°C to support the formation of bainite and retained austenite stabilization was also investigated. Mixed ferritic-bainitic-martensitic structures with some retained austenite content were obtained.
Effect of Cooling Rate below Ms Temperature on Hydrogen Embrittlement of TRIP-Aided Martensitic Steels
Authors: Kakefuda Naoya , Aizawa Shintaro , Sakata Ryo , Kobayashi Junya , Itoh Goroh , Hojo Tomohiko
Published: January 2021

Low alloy TRIP steel is expected to be applied to automobile bodies because of its high strength, high ductility, and excellent impact properties and press formability. It has been reported that the low alloy TRIP steel of hydrogen embrittlement resistance is improved by utilizing the hydrogen storage characteristics of highly stable retained austenite. Therefore, for the purpose of increasing the volume fraction of retained austenite, it was produced at various cooling rates below the martensite transformation start temperature. As a result, the volume fraction of retained austenite increased, and then the effect of hydrogen embrittlement decreased. The matrix phase and retained austenite is refined with decrees of the cooling rate. It is considered that the size and surface area of the retained austenite also affected the improvement of hydrogen embrittlement resistance.
Carrier Concentration of CeFe2Al10 as a Candidate of Thermoelectric Material
Authors: Kawamura Yukihiro , Sekine Chihiro , Nishioka Takashi
Published: January 2021

The study of Hall effect of Kondo semiconductor CeFe2Al10 is reported as a candidate of thermoelectric material used at low temperatures. Single crystals of CeFe2Al10 with orthorhombic crystal structure were grown by Al self-flux method. An anisotropy of the Hall effect is clarified by measuring Hall resistance by changing the direction of electrical current, magnetic field, and voltage respect to all the three crystal axes of orthorhombic crystal structure. The Hall effect of CeFe2Al10 has a strong anisotropy against the direction of magnetic field but weak anisotropy against the directions of current and voltage. The value of carrier concentration indicates that CeFe2Al10 is matallic, which causes a low performance as a thermoelectric material. In order to improve the value of dimensionless figure of merit, the electrons should be doped to CeFe2Al10.
Magnetic and Mechanical Properties of Fe-Cr-Si-Mo Alloys by MIM Process
Authors: Kimura Masahiro , Shimizu Toru , Watari Hisaki
Published: January 2021

In recent years, metal injection molding (MIM) has been adopted as a process for manufacturing a solenoid valve which is a component of an electronic fuel injector, and PB permalloy components have been commercialized. However, Ni, an element of PB permalloy, is expensive material, making it difficult to produce the fuel injector component at a low cost. As a solution to this problem, we studied the magnetic and mechanical properties of Fe-Cr-Si alloys by MIM process. These results revealed that the magnetic and mechanical properties were improved by reducing Cr content. However, reducing Cr content is expected to reduce corrosion resistance of the alloys. In this study, Fe-Cr-Si-Mo alloy specimens containing Mo to improve corrosion resistance are manufactured by MIM process, and we investigated the magnetic and mechanical properties. These results revealed that Fe-10Cr-3Si-2Mo alloy is a material with an excellent balance between magnetic and mechanical properties.
Structural Changes in Multi Principal Element Alloys in Dependence on the Aluminium Content
Authors: Kirschner Johannes , Eisenmenger-Sittner Christoph , Bernardi Johannes , Großalber Alexander , Frank Simon , Simson Clemens
Published: January 2021

The development of novel light metal alloys represents an important task in the further optimization of technical materials. Multi-component systems with more than 4 metals are very promising to outperform currently existing alloys, but lack significant research in systems not dominated by transition metals to date. In this work, alloys containing the elements Al, Cu, Mg and Zn were produced using magnetron sputter deposition. A detailed structural investigation using electron microscopy provided valuable insights into the influences of different metals and their relative proportions in the alloy on material properties.
Shape Memory Properties of Ti-Ni Shape Memory Alloy / Shape Memory Polymer Composites Using Additive Manufacturing
Authors: Kitamura K.
Published: January 2021

Shape memory alloys (SMAs) have the disadvantage that cooling is difficult and the actuating speed during cooling is slow. To resolve this problem, shape memory material actuators that operate only with heating is required. SMAs are characterized by a low apparent Young's modulus below the transformation temperature and a strong shape recovery force above the reverse transformation temperature. Alternatively, shape memory polymers (SMPs) have two properties: shape fixability and shape recovery. The SMPs are hardened below the glass transition (Tg) temperature and the material is recovered to memorized shape above the Tg temperature. The other hand, 3D printer is a machine that can directly output a 3D-designed product designed by a computer in 3D, and molded materials such as polymer, resin, metal, and ceramics. In this research, we developed the SMC of SMA wire and SMP sheet using adhesive that develops actuates into two shapes only by heating.
Fabrication of Three-Dimensional Microstructure Film by Ni-Cu Alloy Electrodeposition for Joining Dissimilar Materials
Authors: Kobayashi Tatsuya , Shohji Ikuo
Published: January 2021

Metals with a three-dimensional microstructure film can be joined to plastics by the anchor effect. The three-dimensional microstructure films can be electrodeposited by a Ni-Cu alloy. In this study, the effects of the ratio of the concentration of Ni amidosulfate and Cu sulfate in the plating solution and plating current density on the shapes and microstructures of electrodeposited films were investigated. When the ratio of the concentration of the Ni amidosulfate and the Cu sulfate is 0.47-1.4:0.06 (M/L), a dendritic-type electrodeposited structure was generated at plating current density of 10 mA/cm2. When the ratio of the concentration of the Ni amidosulfate and the Cu sulfate is 0.47:0.6-1.2 (M/L), a feathery-type and needle-type electrodeposited structure was generated.
Severe Plastic Deformation of Copper, Binary Cu-Zn Solid-Solution Alloys, and High-Strength Brass by High-Pressure Torsion
Authors: Kunimine Takahiro
Published: January 2021

Severely-deformed high-strength brasses were investigated by leveraging high-pressure torsion (HPT) processing in order to obtain more enhanced mechanical properties of copper alloys. Pure copper, binary Cu-Zn solid-solution alloys and high-strength brasses including aluminum and manganese additions were selected for experiments. For comparison of these materials, zinc equivalent parameter was used. These materials were subjected to the HPT processing, followed by hardness tests and tensile tests. The maximal hardness value of the nanostructured high-strength brass with β phase matrix was reached 420 HV. The HPT processed high-strength brass with β phase matrix showed significant increase in the yield stress and tensile strength with sacrificing ductility. The tensile specimen of the high-strength brass with β phase matrix was fractured before initiation of necking. It was found that utilizing β phase matrix is also beneficial for controlling enhanced strength of high-strength copper alloys for not only casting process but also severe plastic deformation.
Structural Characterization of a Biogenic Secretion Extracted from the Tendon or Ligament in Rabbits for Artificial Ligament Formation
Authors: Kuzumaki Toru , Yamaguchi Tatsuya , Shimozaki Kengo , Nakase Junsuke , Torigoe Kojun
Published: January 2021

Thus far, our research group has conducted a basic investigation for the development of an artificial ligament, which was performed by utilizing a biogenic secretion that was derived from the Achilles tendon in mice; this was achieved using the film model method. In this study, an attempt has been made to derive a biogenic secretion from the Achilles tendon (tendon gel) and the medial collateral ligament (ligament gel) in rabbits. Subsequently, a discussion was carried out on the possibility of forming a ligament-like structure that was based on the structural, mechanical, and spectroscopic investigations. The tendon gel was successfully formed from a parent tendon that was preserved in vivo for 3, 5, 10, and 15 d. Further, an aligned collagen fiber emerged in the tendon gel, which was subjected to tension on every preservation date. Further, the mechanical behavior of the tendon gel specimens was classified in two groups. The values of the Young's modulus of the specimens preserved for 10 and 15 d were higher than those of the specimens preserved for 3 and 5 d. Within the range of this experimental condition, the aligned collagen fiber structure was formed by applying a tension of approximately greater than 0.05 N. Conversely, only a 10-d preservation period yielded a sufficient amount of ligament gel for the experiment. Notably, the volume of ligament gel was less than that of the tendon gel. In the ligament gel specimen without the synovial membrane, the collagen fiber structure was formed by applying a tension, which was similar to that experienced by the tendon gel specimen. However, the cross-linking and growth of collagen fibers in the ligament gel samples were insignificant as compared with those of the tendon gel samples.
Enhancing High-Temperature Creep Resistance of In Situ TiAl-Based Matrix Composite by Low Volume Fraction of Ti2AlC Particles
Authors: Lapin Juraj , Kamyshnykova Kateryna
Published: January 2021

Samples of TiAl-based matrix in-situ composite with the chemical composition Ti-46.4Al-5.1Nb-1C-0.2B (at.%) reinforced with a low volume fraction of primary Ti2AlC particles were prepared by vacuum induction melting in graphite crucibles and centrifugal casting into graphite moulds. The hot isostatic pressing (HIP) of the as-cast samples and subsequent heat treatments leads to the formation of equiaxed grains with fully lamellar α2(Ti3Al) + γ (TiAl) microstructure and uniformly distributed Ti2AlC and TiB particles. The minimum creep rates of the in-situ composite are significantly lower compared to those measured for the counterpart low carbon benchmark alloy with the chemical composition Ti-47Al-5.2Nb-0.2C-0.2B (at.%) at temperatures ranging from 800 to 900 °C and applied stress of 200 MPa. The studied in-situ composite shows also significantly improved creep resistance compared to that of some TiAl-based alloys with fully lamellar, convoluted and pseudo-duplex microstructures at a temperature of 800 °C and applied stress of 200 MPa.
Impact of Microstructural Anisotropy of As-Cold-Sprayed Cu Deposits on its Annealing Effect
Authors: Li Yu Juan , Wei Ying Kang , Luo Xiao Tao , Li Chang Jiu
Published: January 2021

Cold spraying is being developed as effective and promising additive manufacturing process. However, how to create a deposit by cold spraying with comparable properties to bulk material is still challenge. It is well known that post-spray annealing is an effective process to enhance the deposit properties. In this paper, copper deposits are cold-sprayed at three different sets of spray conditions corresponding to three mean particle velocities of 578, 745, and 807 m/s. The tensile strength, thermal conductivity and electrical conductivity are measured at three different directions to clarify the anisotropy of deposit properties, which are parallel to gun moving direction and other two perpendicular directions. Furthermore, the influence of post-spray annealing on the anisotropy effect is also investigated by examining the effect of spray conditions and annealing conditions on the deposit properties at three different directions. The results clearly demonstrate the anisotropy of as-deposited Cu. Although it can be found that post-spray annealing significantly improves the properties of the as-sprayed deposits and reduces anisotropy of Cu deposit properties, the microstructure of the as-sprayed initial Cu deposit presents a significant effect on final annealed deposit. Therefore, an optimized cold-sprayed deposit will benefit manufacturing of a deposit with comparable properties with bulk by cold-spraying combined with post-spray annealing.
Performance of 14Cr ODS-FeCrAl Cladding Tube for Accident Tolerant Fuel
Authors: Li Jing , Wu Sa Jian , Wang Yong Li , Xiong Liang Yin , Liu Shi
Published: January 2021

In the framework of Accident tolerant fuel (ATF) program, several types of claddings and pellets with enhanced accident tolerance have been developed for light water reactors. Oxide dispersion strengthened (ODS) FeCrAl alloys have been considered as a promising candidate for cladding materials due to their good mechanical strength, excellent structural stability and chemical durability at high temperature. The out-of-pile performance of 14Cr ODS-FeCrAl cladding tube fabricated by cold-rolling, such as microstructure, thermophysical property, mechanical property, and corrosion resistance, has been examined and discussed. The results confirm that iron-based ODS alloy is one of the promising candidates to be used as ATF cladding. It could also aid in the supplement of property database of ODS-FeCrAl for future use in nuclear cladding and structural applications in next generation nuclear systems.
Inhomogeneous Microstructure and its Thermal Stability of AlSi10Mg Lattice Structure Manufactured via Laser Powder Bed Fusion
Authors: Liu Mu Lin , Takata Naoki , Suzuki Asuka , Kobashi Makoto
Published: January 2021

The inhomogeneous microstructure and its change by annealing for an AlSi10Mg lattice structure with a body-centered cubic unit cell additively manufactured via laser powder bed fusion (LPBF) were investigated. The as-built lattice structure exhibited a cellular microstructure consisting of a number of primary α-Al phases decorated with α-Al/Si eutectic structure. The developed microstructure varied depending on the locations of the node and strut parts of the lattice structure. At the location near the bottom surface of the node part, the cellular microstructure became coarser and more equiaxed than those at the location near the top surface. At the location near the bottom surface of the strut part, the columnar α-Al phases were often elongated along the direction of the strut part. After the annealing at 300 °C for 2 h, numerous Si particles finely precipitated within the primary α-Al phases and coarsening of the eutectic Si phases occurred. After the annealing at 530 °C for 6 h, the microstructural characteristics changed significantly. A significant coarsening of the Si particles and the formation of Fe-containing intermetallic phase (β-AlFeSi) with a plate-shaped morphology occurred. The microstructures became homogeneous in the whole area of the lattice structure annealed at 530 °C for 6 h.
Study of Nb Solubility in Hot Charging Process
Authors: López Beatriz , Pereda Beatriz , Bastos Felipe , Rodriguez-Ibabe J.M.
Published: January 2021

The aim of this work is to investigate the dissolution behavior of Nb in hot charging hot rolling configurations. To do so, an indirect experimental procedure is used to quantify the amount of Nb present in solution before rolling. The method is based on the effect of dissolved Nb on static recrystallization kinetics due to its solute drag effect. After different thermal cycles, simulating cold and hot charging conditions, double hit torsion tests have been performed with a 0.23%C steel microalloyed with 0.03% Nb. By means of these tests, the static softening behavior has been determined. Comparison of the recrystallization times allows indirect evaluation of the amount of Nb in solid solution after each treatment. The results have been correlated with the precipitation state of the samples.
Defect Reduction and Quality Optimization through the Modelling of Plastic Deformation and Metallurgical Evolution
Authors: Mancini Silvia , di Nunzio Paolo Emilio , Notargiacomo Sandro , Langellotto Luigi
Published: January 2021

The finite element modelling is a well-established technique in studies of plastic deformation. Many commercial codes, both general purpose or dedicated, implement general constitutive laws sufficient for a first level use. However, some issues need to be addressed by using specific formulations or require more advanced modelling to take into account complex behaviors. In the present contribution, an overview of the main issues that arise in the study of hot deformation processes and their theoretical and software tools available in CSM SPA is presented with their applications to industrial cases. The overview on methodologies for modelling of plastic deformation starts from the more conventional rheological laws, through the implementation of innovative rheological laws, the microstructural and mechanical coupling and tailored material characterization and concludes with the identification of criteria for the evaluation of the internal quality of the finished products, such as the porosity closure. The applications presented concern mainly the rolling of long products.
Grain Boundary Engineering of Strain-Annealed Hastelloy-X
Authors: Muhammad Waqas , Wei Daniel , Martin Étienne
Published: January 2021

The present study investigates the occurrence and effectiveness of the dissociation mechanism of Σ3 CSL boundaries into its variants such as Σ9 and Σ27a-b during strain-annealed grain boundary engineering (GBE) of Hastelloy-X. Multiple cold-rolling strain levels and annealing conditions are studied and it is observed that the density of ∑3 boundaries decreases proportionally to the amount of strain induced boundary migration (SIBM) during the GBE process. The dissociation mechanism of Σ3 annealing twins is activated at the onset of SIBM, causing an increase in the density of the Σ3n variants. It is shown that at high annealing times or temperatures, the rate of generation of CSL boundaries through dissociation mechanism is lower than their annihilation rate. It is further suggested that the dissociation mechanism of ∑3 boundaries during GB migration is more efficient when the amount of applied strain prior to annealing is kept low, thus promoting disruption of the random GB network.
Effect of Stress Gradient on Heat Cycle Fatigue Life Prediction of Solder Joints by Repetitive Bending Test
Authors: Matsushima Michiya , Endo Kei , Kawazoe Tetsuya , Fukumoto Shinji , Fujimoto Kozo
Published: January 2021

Strength of solder joints is usually evaluated by a shear test and a pull test. The reliability of the solder joint is evaluated by the repetitive pull tests of solder bulk specimens. However, the stress and strain field that caused by thermal load on the solder joint of the product model for estimating the reliability is different from these tests. Therefore, we proposed a repetitive bending test as a reliability test of solder joints producing the stress and strain field caused at the solder joint of product model. We proposed a repetitive multi-point bending test as a method to predict the fatigue life of the solder joint in the thermal cycle test in a short period of time. The influence of strain gradient on the inelastic strain amplitude used for lifetime evaluation is estimated. The controllability of the strain gradient by the three-point bending test parameters is investigated. The effect of residual stress on inelastic strain amplitude during sample preparation for thermal cycle test is also evaluated.
Nickel Supported Modified Zirconia Catalysts for CO2 Methanation in DBD Plasma Catalytic Hybrid Process
Authors: Mikhail Maria , da Costa Patrick , Cavadias Simeon , Tatoulian Michael , Ognier Stephanie , Galvez Maria Elena
Published: January 2021

The methanation reaction has recently received considerable attention as a perspective CO2 utilization technology leading to the formation of renewable natural gas methane. This reaction is favorable at low temperature, but it is hindered of slow kinetic rates, whereas below a temperature of 270°C, the CO2 conversion is practically 0, and at higher temperatures, 350-400°C, the co-existence of secondary reactions favors the formation of CO. This is the reason why new catalysts and process conditions are continuously being investigated to maximize the methane selectivity, preferably at low reaction temperatures and at atmospheric pressure. Thus, this work is focused on the use of a heterogeneous catalyst Ni/ Zirconia supports modified by rare earth metals such as Lanthanum, tungsten and Yttrium combined to a Dielectric Barrier Discharge plasma. Three catalysts were prepared by a conventional wet impregnation method, using 15 wt% of Ni loading over zirconia supports modified with different promoters. To better define the physical, textural and chemical properties, the catalysts were characterized by the means of BET, XRD, H2-TPR, CO2-TPD. The influence of basicity, Ni crystallite size and the Ni-support interaction on the catalytic activity was clearly evidenced.
Physical Modelling of Strain Induced Roughness of Copper Wire during Dieless Drawing Process
Authors: Milenin Andrij , Byrska-Wójcik Dorota , Wróbel Mirosław
Published: January 2021

One of the possibilities of the dieless drawing is the production of ultrafine wire. In this case, it is possible for additionally stretch the wire, obtained in the conventional way. This may allow to obtain a wire of smaller diameter than the industry produces. However, the significant problem is the increase of the strain induced roughness of wire during dieless drawing. This problem has become important due to the fact that the resulting roughness can be comparable to the diameter of the wire and significantly reduce the workability. Thus, the solution of these problems requires plastometric studies of the material, physical and numerical modeling for prediction the roughness of the wire under conditions of dieless drawing. The experimental study shown, that the surface roughness of the copper wire after dieless drawing increases significantly at a deformation temperature above 300°C. The total roughness is associated both with the formation of oxides and the strain induced roughness.
Creep Resistance of Ultrafine-Grained VT8M-1 Alloy
Authors: Modina Iuliia Mikhailovna , Polyakov Alexander V. , Dyakonov Grigory , Yakovleva Tatyana Vitalyevna , Stotskiy Andrey G. , Valiev Roman , Semenova Irina P.
Published: January 2021

This paper is aimed to study the creep behavior of two-phase ultrafine-grained VT8M-1 (Ti-5.7Al-3.8Mo-1.2Zr-1.3Sn) titanium alloy obtained by rotary swaging (RS). It is shown that the 100-hour creep strength of the ultra-fine grained (UFG) VT8M-1 alloy retains high values at temperatures up to 400 °C. An increase in the testing temperature to >450 °C leads to a decrease in the creep rupture strength. The relationship between the microstructure and creep resistance of UFG alloy is discussed.
The Domain of Portevin-Le Chatelier Effect in Al-3Mg Alloy
Authors: Mogucheva Anna , Yuzbekova Diana , Borisova Yuliya Igorevna
Published: January 2021

An Al-3Mg (wt. %) alloy was studied after equal channel angular pressing and subsequent cold rolling. The mechanical behavior of the alloy in the temperature range from 223 K to 373 K (from –50°C to 125°C) at strain rates 2.1×10–1 – 5.2×10–5 s–1 was investigated. The analysis of stress-strain curves was performed to determine the conditions of manifestation of the Portevin – Le Chatelier (PLC) effect in investigated alloy. The deformation curve at a temperature of 298 K (25°C) and a strain rate of 1×10–3 s–1 is characterized by instability of plastic flow in contrast to the deformation curves obtained under other studied strain rate/temperature conditions. Stress oscillations at the necking stage were observed at high temperatures (>323 K (50°C)) and lower strain rates (1×10–4 s–1 and 5.2×10–5 s–1) forming the left border of the PLC effect domain. In general, deformation curves are characterized by the absence of stress serrations during the uniform elongation.
The Effect of Hydrofluoric Acid Concentration in Sulfuric Acid-Based Desmutting Solution for Aluminium Alloys
Authors: Monetta Tullio , Carangelo Anna , Bravaccino Francesco , Sinagra Ciro , Acquesta Annalisa
Published: January 2021

The natural oxide layer, which spontaneously covers the surface of aluminium and its alloys, is well adherent to the surface, but it does not show adequate corrosion resistance in many conditions. In order to improve the material anti-corrosion performance, it is necessary to replace the surface oxide by a conversion coating. The first step to do this is to prepare the alloy surface to subsequent treatments. The pre-treatment implemented before the conversion treatment is one of the main factors responsible for the performance of the conversion coating. It involves several phases, including desmutting that encompasses the part immersion in an acid or alkaline solution bath. In this work, the influence of hydrofluoric acid concentration in the desmutting bath's formulation was investigated. The samples surface were characterised by using electrochemical techniques, glow discharge optical emission spectrometry and contact angle measurements.
Strain Rate Dependent Mechanical Stability of Retained Austenite in Hot-Rolled Medium-Mn Sheet Steels
Authors: Morawiec Mateusz , Grajcar Adam
Published: January 2021

The paper presents microstructural and mechanical results of medium manganese steel deformed under high strain rates. The rotary hammer tests at strain rates of 250, 500 and 1000 s-1 were applied. Mechanical properties under dynamic tensile loads were determined. According to the obtained results, when strain rate increased the yield point of the steel increased. An opposite trend was present regarding total elongation. In case of tensile strength, its level is similar for all analyzed deformation rates. The microstructure of the steel after the dynamic tensile test is composed of bainite, martensite and martensitic-austenitic islands. The strain-induced martensitic transformation was identified in microscopic investigations.
Extra-Hardening of SPD-Processed Al-Mg Alloy with Minimum Grain Sizes
Authors: Morishige Taiki , Suzuki Yuto , Takenaka Toshihide
Published: January 2021

Severe plastic deformation (SPD) processing of Al alloys could obtain high strength by grain refinement mechanism. The minimum grain size of Al alloy, obtained at higher strain rate at low temperature, is determined the stacking fault energy of the alloy. SPD-processed pure Al metal, has high stacking fault energy, has relatively large grain size. During SPD processing, large strain is introduced, and the dislocation is rearranged in the specimen. The re-arrangement of dislocation in SPD-processed Al alloy with intermediate stacking fault energy significantly delayed, thus the strain remains in the grain interior. The extra-hardening, a kind of strain hardening, results from an incomplete of dynamic recrystallization during SPD processing. Al-Mg solid solution alloy has intermediate stacking fault energy and the minimum grain size of this alloy approaches about 200 nm after SPD. The mechanical property of this alloy is remarkably higher than the predictable strength by Hall-Petch relationship due to the extra-hardening. In addition, the increase in strength by the extra-hardening varies with the Mg content of Al-Mg alloy. In this study, the effect of Mg content, i.e. the stacking fault energy of the alloy, on the degree of the extra-hardening of SPD-processed Al-Mg alloy was investigated in terms of the dislocation density and low-angle grain boundary of the alloy.
Effects of Retained Austenite Conditions on the Ductility of the Advanced High Strength Steels
Authors: Murakami Toshio
Published: January 2021

It was investigated that the effects of retained austenite (γR) conditions on ductility of advanced high strength steels for automotives. 0.4mass% C steels were heattreated in various austemper conditions to control the retained austenite conditions. In the result of the evaluation of mechanical properties of these steels, it was confirmed there were steels which indicated different elongation even if they had almost same volume fraction and carbon content of retained austenite. In order to clarify the reason, the conditions of retained austenite and work hardening behavior were investigated in detail. It was indicated that the existence of high carbon content region in a part of retained austenite promoted the deformation induced martensitic transformation in the high strain range and improved the elongation of AHSS.
Solid State Amorphization and Alloy Parameters for High Entropy Alloys
Authors: Nagase Takeshi
Published: January 2021

Fast electron irradiation can induce the solid-state amorphization (SSA) of many intermetallic compounds. The occurrence of SSA stimulated by fast electron irradiation was found in the Al0.5TiZrPdCuNi high-entropy alloy (HEA). The relationship between the occurrence of SSA in intermetallic compounds under fast electron irradiation and the empirical alloy parameters for predicting the solid-solution-formation tendency in HEAs was discussed. The occurrence of SSA in intermetallic compounds was hardly predicted, only by the alloy parameters of δ or ΔHmix, which have been widely used for predicting solid-solution formation in HEAs. All intermetallic compounds with ΔHmix ≤ -35 kJ/mol and those with δ ≥ 12.5 exhibit the occurrence of SSA. This implies that the intermetallic compounds with a largely negative ΔHmix value and a largely positive δ parameter are favorable for the occurrence of SSA.
Corrosion Resistance Evaluation of a Stainless-Steel Brazed Joint in HCl Solution
Authors: Nagata Hikaru , Ono Masa , Miyazawa Yasuyuki , Hayashi Yuji , Bizen Yoshio
Published: January 2021

To clarify the effect of the acid solution type on corrosion resistance, the corrosion behavior of stainless steel brazed joints in HCl aqueous solution was evaluated through electrochemical measurements. Anodic polarization curves of a ferritic stainless-steel base metal, Ni-based brazing filler metals, and a brazed joint were recorded. In addition, in situ observations were conducted to observe the corrosion behavior of each structure of the brazed joint. Corrosion potentials of the brazing filler metal were lower than that of the base metal. In situ observations of the brazed joint revealed the order of corrosion in aqueous hydrochloric acid. According to the electrochemical measurements, under an actual corrosive environment, the brazing filler metal can function as an anode and selectively corrode. In addition, the anodic polarization curve of the brazed joint showed values between those of the polarization curves of the brazing filler metal and the base metal, indicating that the corrosion resistance could be electrochemically evaluated in HCl aqueous solution.
Regularity for the Boltzmann equation conditional to macroscopic bounds
Authors: Imbert Cyril , Silvestre Luis
Published: January 2021

The Boltzmann equation is a nonlinear partial differential equation that plays a central role in statistical mechanics. From the mathematical point of view, the existence of global smooth solutions for arbitrary initial data is an outstanding open problem. In the present article, we review a program focused on the type of particle interactions known as
non-cutoff
. It is dedicated to the derivation of a priori estimates in

C^\infty

, depending only on physically meaningful conditions. We prove that the solution will stay uniformly smooth provided that its mass, energy and entropy densities remain bounded, and away from vacuum.
Detection and Phylogenetic Analysis of Fish Viruses Inhabiting Freshwater Ornamental and Food Fish Species in India: A Survey-Based Study
Authors: Bajpai Vertika , Pragyan Divya , Mohanty Jyotirmaya , Sahoo Pramoda Kumar
Published: January 2021

Molecular screening of viruses through PCR is a fast detection method and several variants of it have been developed to meet the shortcomings of conventional method. Extensive surveillance is an essential tool to have an estimate of circulating potential viruses in Indian aquatic systems. The present study focuses on standardization of semi-quantitative PCR-based diagnostics for eight freshwater fish viral pathogens and documents number of positive incidences after screening 437 numbers of samples during 2017-2020 for suspected fifteen freshwater finfish viral pathogens. Positive samples of Cyprinid herpes virus-2, carp edema virus and viral nervous necrosis virus from different regions of eastern Indian states viz., Odisha, West Bengal and Assam have given a scope of comparative phylogenetic analysis of strain variability in detail. Nevertheless, the study highlights the importance of rendering protection to native cultured fish by preventing their introduction and further spread on a local or national scale to either known or unknown susceptible fish species available in the region, and emphasize upon strengthening surveillance system.