bluuebunny/crossref_metadata_2025 huggingface dataset:
Rapid Manufacturing Experience in Training
Authors: Hernández P. , Monzón M.D. , Benítez A.N. , Marrero M. , Ortega Z. , Díaz N. , Ortega F.
Published: July 2013

Rapid Manufacturing (RM) is considered as a set of innovative manufacturing technologies, many of which are in continuous development phases, and are becoming increasingly important to develop new products with high added value. Procesos de Fabricación research group, at the University of Las Palmas de Gran Canaria (ULPGC) is a founding member of the Spanish Rapid Manufacturing Association (ASERM), and has over ten years of expertise in research, transfer and training activities in these new technologies. ASERM, marked among its strategic objectives to promote and support RM training. As a result of this, the association participates in the European Project named Knowledge Transfer of Rapid Manufacturing (KTRM). Ingeniería de Fabricación educational innovation group (GIEIF) from ULPGC is working along other partners in this project and other training activities, because of the knowledge gained in these technologies.
Quality Training and Research around the Machine Tools
Authors: Rodríguez A. , Tabernero I. , Martínez S. , Lamikiz Aitzol
Published: July 2013

The best is to read these instructions and follow the outline of this text. The text area for your manuscript must be 17 cm wide and 25 cm high. The High Performance Manufacturing Group of the Faculty of Engineering of Bilbao has a workshop fully-equipped. In this way, these machine tools are valid both to support research carried out by the Group and also to improve teaching lessons, both theoretically and practically.
In this paper, the case of a five-axis milling machine was presented and analyzed. Each year, the new students are taught to design various systems of the machine and they are also encouraged to make some practical tests. This dual use of machines is very useful since it allows to carry out high level researches, as well as to train new students in theoretical and practical issues.
Wikipedia as a Tool for Active Learning. Experience Gained within the Framework of the Wikifabricación Project
Authors: Abellán-Nebot J.V. , Bruscas G.M. , Serrano J. , Romero F.
Published: July 2013

Wikipedia, the Free Encyclopedia, is one of the most visited websites on the Internet and it is a tool which students often use in their assignments, although they do not usually understand the basics underlying it. To overcome this limitation and promote the active learning approach in our courses, last year an educational innovation project was carried out that was aimed mainly at improving students skills in technical writing as well as their ability to review the technical contents of the Wikipedias. Additionally, it sought to explore new opportunities that these tools can offer both teachers and students. This paper describes the experiment carried out in a second-year undergraduate engineering course, the results of which show that introducing activities such as edition and revision within Wikipedia is an interesting way to enhance transversal competencies as well as others related to the main contents of the course.
Teaching-Learning Methodology of Progressive Die Design Based on Solidworks®
Authors: Miguel V. , Naranjo J. , Manjabacas M. Carmen
Published: July 2013

The present work describes a design experience related to a progressive die carried out with Solidworks®. The potential of uses of this software are emphasized pointing its advantages and the needed designer interaction. The graphic power, the ease of doing draws and the simulation capacity are the main characteristics that authors point out. The possibility of checking some parts by FEM allows to assure the functionality of the manufactured designs. Three different learning strategies are proposed: expositive classes, short-time practices and long-time supervised works.
Synthesis, Molecular Properties and MIC Studies of D-Ring Chalcone Derivatives of 20-Keto Pregnenolone
Authors: Lone Imtiyaz H , Bhat M. Amin
Published: July 2013

An efficient and simple synthesis of 17-chalconyl derivatives of pregnenolone and their antibacterial and antifungal evaluation is reported. The scheme involves the transformation of the starting pregnenolone to the corresponding Chalcone derivatives by the well-known Claisen-Schmidt reaction. Determination of Minimum inhibitory concentrations (MICs) is reported on these newly synthesized Chalcone derivatives of pregnenolone. The prediction of molecular properties is also discussed. Compounds showing lower MIC values also followedLipinski’s rule of 5. The results showed that the activity of the tested agents against each microbe varies due to structural differences between the microorganisms.
Electron Microscopy: A Versatile Tool in Nanoworld
Authors: Shah M.A.
Published: July 2013

Microscopy is the characterization of objects smaller than what can be seen with the naked human eye, and from its inception, optical microscopy has played a seminal role in the development of science. In the 1660s, Robert Hooke first resolved cork cells and thereby discovered the cellular nature of life. Robert Browns 1827 observation of the seemingly random movement of pollen grains [ led to the understanding of the motion that still bears his name, and ultimately to the formulation of statistical mechanics. The contributions of optical microscopy continue into the present, even as the systems of interest approach nanometer size. What makes optical microscopy so useful is the relatively low energy of visible light: in general, it does not irreversibly alter the electronic or atomic structure of the matter with which it interacts, allowing observation of natural processes in situ. Moreover, light is cheap, abundant, and can be manipulated with common and relatively inexpensive laboratory hardware.Science and technology ever seek to build structures of progressively smaller size. This effort at miniaturization has finally reached the point where structures and materials can be built through atom-by-atom engineering. Typical chemical bonds separate atoms by a fraction of a nanometer (109 m), and the term nanotechnology has been coined for this emerging area of development. By manipulating the arrangements and bonding of atoms, materials can be designed with a far vaster range of physical, chemical and biological properties than has been previously conceived. But how to characterize the relationship between starting composition, which can be controlled, with the resulting structure and properties of a nanoscale-designed material that has superior and unique performance? Microscopy is essential to the development of nanotechnology, serving as its eyes and hands.
Extraction of EPS from Mould Fungi Isolated from City Houses and its' Antibiosis against Pathogenic Bacteria
Authors: Nanda Anima , Raghavan M.
Published: July 2013

An aero-allergenic fungus in the indoor environments has been associated with adverse respiratory symptoms leads to different allergenic diseases viz., allergic asthma, bronchitis, rhinitis, and hay fever in the atopic human beings. Moreover, fungal assessment and exposure has traditionally relied upon questionnaires for health issues especially to children. The present study is an attempt to record the incidence and seasonal periodicity of airborne fungal spores in indoors and outdoors of an industrial city house, Hosur, Tamilnadu by Petri-plate settlement method. In qualitative and quantitative way, fungal spores considerably varied from indoors to outdoors as well as from season to season. Apart from fungal growth on culture plates and spore counts, new immunoassays for extracellular polysaccharides (EPS) have enabled quantisation of fungal agents in house dust in a more timely and cost-effective manner, possibly providing a better measure of fungal exposure. The present data investigated outdoor air harbored maximum fungal spores (53%) in comparison to indoor air (47%). Incidence of fungal species was predominated with more number of propagules during mid winter (December) and early rainy (July) periods in comparison to other months. Qualitatively,Aspergilluswas found with the highest frequency and had eleven members i.e.,A. awamori, A. fumigatus, A. niger, A. flavus, A. flavipes, A. nidulans, A. ochraceous, A. japonicus, A. terreus, A. versicolorandA. wentii,but quantitatively,Penicilliumwas isolated highest in its contribution to total CFUs followed byAspergillus. Out of the 32 isolated fungal taxa,Aspergillus fumigatus, A. awamori, A. niger,Rhizopus stoloniferandAlternaria alternatawere the predominant aeroallergens, which cause different types of respiratory/lung diseases among atopic human beings. Samples were sieved and fine dust was analyzed for EPS fromAspergillusandPenicilliumspp., though they are considered as more allergenic. In seasonal periodicity, winter contributed the maximum spore load followed by rainy. Summer was found with the least in harboring the spore mass in the indoors and outdoors.Alternaria alternata,which is accounted as a human allergen for sporosis inducer and an agent for hay fever and other pathologies, was also intermittently recorded. The extracellular polysaccharide (EPS) collected was further treated against the human pathogen to check its antimicrobial activity, which can be used as a good replacement of antibiotics.
Review of Advanced Daylighting Systems
Authors: Rayaz S. , Rubab S.
Published: July 2013

Daylight is the most underutilized resource in modern buildings. Artificial light can be dispensed away in institutional buildings such as offices, banks, schools etc. having only daytime occupancy by proper architectural design of fenestrations The design of a day lighting space is both an art and a science. The biggest challenge facing the lighting designer is to admit only as much light as necessary and distribute it evenly throughout the space without introducing glare or heat. In hot / warm climates, it has become common practice in windows spaces to specify blinds and glazing with high shading coefficients to control glare and minimize heat gain. However, this practice reduces the effectiveness of lighting systems that dim automatically. Improved systems are needed to capture natural daylight and distribute it uniformly throughout a space while controlling heat gain and glare. One such system is the light shelf. Light shelves shade the space from direct sunlight and reflect this sunlight onto the ceiling for a deeper and more uniform distribution. Reflective blinds offer good control of glare and solar protection. Innovative day lighting systems are designed to redirect sunlight or sky light to areas where it is needed with excessive luminance and glare. These systems use optical devices that initiate reflections, refractions, and / or use total internal reflection of sunlight and sky light. Advanced day lighting systems can be designed to actively track the sun or passively control the direct sunlight and sky light. In this paper, we review the state of the art of several advanced day lighting systems which are designed to maximize the energy-saving potential of day lighting, while improving comfort and visual performance at an “affordable” cost.
Reduction Kinetics of Chromite Pellets
Authors: Khan D.M.A.
Published: July 2013

Plain Chromite and Ore- Coal/charcoal Compositepellets were Reduced in the CO Atmosphere between 1350°C and 1600°C in a Superkenthal Muffle Furnace. the Reaction Followed the Path of First Order Reductionkinetics and the Reduction was under Chemical Reaction Rate Control. Theactivation Energy was Calculated in the Range from 225KJ/mole to 342KJ/mole.The Insitu Carbon Present in the Composite Pellets Motivated the Gasificationreaction of Carbon and the Reduced Fe and Cr Act as the Catalysts to Propagatethe Reduction in the Forward Direction.
Characterization of HA/Ta Composite Coatings Fabricated by Vacuum Plasma Spraying
Authors: Huang Li Ping , Xie You Tao , Ji Heng , Zeng Yi , Zheng Xue Bin
Published: July 2013

Plasma sprayed hydroxyapatite (HA) coatings on titanium alloy substrates have been used extensively due to their excellent biocompatibility and osteoconductivity. However, the low bonding strength between HA and Ti substrates is still problematic in the long-term implantation lifespan. In this paper, HA/Ta composite coatings with various Ta contents (20% and 60%) were fabricated by vacuum plasma spraying (VPS). The microstructure, phase composition of the coatings was characterized by scanning electron microscopy (SEM) and X-ray diffraction (XRD), respectively. The results revealed that the coatings had a rough surface and lamellar structure including some pores. ASTM C-633 standard was used for the measurement of bonding strength, which was found increasing with the increase of Ta contents in the composite coatings. The bonding strength of the composite coating containing 60% Ta (H4T6) reached to 37.2 MPa, which is about 1.9 times that of HA coating. In vitro bioactivity evaluated in simulated body fluids (SBF) showed that bonelike apatite layer was formed on the composite coatings surface, which indicated the good bioactivity of the HA/Ta composite coatings.
Responses of Human Bone Marrow-Derived Stromal Cells to Calcium Silicate Coatings with Different Chemical Stability
Authors: Xie You Tao , Huang Li Ping , Zheng Xue Bin
Published: July 2013

Abstract: Calcium silicate (CS) ceramics have good biocompatibility, high bonding strength with titanium alloy substrates, and are potential candidates for implant coating materials. The osteo-integration of coated implants with host bone tissue is greatly affected by the degradation of these coating materials in biological fluid. In this paper, zirconia adopted calcium silicate (CaO-ZrO2-SiO2, CZS) ceramic powder was synthesized. Plasma spraying was used to prepare the coating with Ti-6Al-4V as substrates. Human bone marrow-derived stromal cells (hBMSCs) culture system was used to evaluate the cytocompatibility of the CS and CZS coatings. Results showed that more cells were adhered to the CZS coating with high proliferation ratio than those on CS. The dissolution of CS and hereby elevated pH value were contributed to the decreased cell adhesion and proliferation.
Oxidation of Tantalum Nitride
Authors: Hamaguchi Kazuya , Tsuchiyama Tomoyuki , Matsushita Junichi
Published: July 2013

Tantalum (Ta) can be use a suture for operation and implant material in order not to react with body fluid and stimulate a human body. In this study, the stable oxide of a tantalum, tantalum oxide layer produced by oxidation of the tantalum nitride, TaN powders by high temperature oxidation were investigated in order to determine the possibility of its a distributed aid for biomaterial composite such as an artificial root etc. The sample, TaN powder oxidized at high temperature exhibited a steady mass gain with increasing oxidation temperature. Based on the results of the XRD, tantalum oxide, Ta2O5 was detected on the samples. It is considered, the TaN showed a good oxidation film produced by high temperature oxidation.
Characterization and Cell Response of Novel Hydroxyapatite/Glyceride-Based Polyurethane Porous Scaffold
Authors: Du Jing Jing , Zuo Yi , Zou Qin , Li Yu Bao
Published: July 2013

The glycerides of castor oil (GCO) were copolymerized with isophorone diisocyanate (IPDI) to generate glyceride-based polyurethane (GCPU), meanwile blending with hydroxyapatite (HA) powder to fabricate porous composite scaffolds. The effect of HA content on mechanical properties of the resulting polymer scaffolds and the in vitro cell response of HA/GCPU scaffolds were investigated, by use of mechanical testing, FTIR, SEM and MTT assay. The results showed that the compressive strength increased with HA content, and the HA/GCPU scaffold with 40 wt% HA reached about 4.6 MPa, much higher than the scaffold without HA (only 605 kPa). The SEM observation, live-dead staining assay and MTT assay demonstrated the excellent biological properties of HA/GCPU scaffolds, which support cell adhesion and proliferation. This novel class of HA/GCPU porous scaffolds have prospect and advantage for bone repair and regeneration.
Effect of Pore Forming Agent on Microstructures and Properties of Porous Molybdenum
Authors: Lu Zhen Lin , Rao Xiao Jie , Xu Xiao Feng
Published: July 2013

The porous molybdenum was prepared by addition of pore forming agent and powder metallurgy method. The results show that the species and amount of pore forming agent are the primary influencing factors for the microstructures and properties of porous molybdenum. The pore shapes in porous molybdenum are regular and uniformly distributed. The porosity of porous molybdenum would be the largest and the transmission rate would be the best when sodium chloride was selected as pore forming agent. The compressive fracture strength of porous molybdenum would be more than 30MPa when the ammonium hydrogen carbonate was selected as pore formimg agent and its addition was 70 % (volume fraction). But the porosity would be the lowest.
Relationship between Nitrogen Content and Mechanical Properties in Al1-xCrxNy Thin Films
Authors: Pham Thi Huyen Tram , Paumier Fabien , Le Bourhis Eric , Goudeau Philippe
Published: July 2013

To get further insight into Nitrogen stoichiometry influence which is of utmost importance since it influences the phase structure and consequently the mechanical properties of the AlCrN coatings, we carried out a systematically study of AlCrN coatings comprising coatings production, mechanical properties survey, and composition and phase structure characterizations. Al1-xCrxNythin films have been synthesized by two physical vapour deposition - PVD systems: ion- beam (IBS) and magnetron sputtering (MS). Composition of the coatings was studied by both Energy Dispersive X- ray Spectrometer (EDXS) and Rutherford Backscattering Spectroscopy (RBS), the latter technique being very sensitive to light elements such as nitrogen. Most compositions are revealed to be sub- stoichiometric with Nitrogen (y 1-xCrxNyfilms show a similar coefficients of friction (COF) evolution with average values observed between 0.4 – 0.8 depending on the nitrogen content.
Feasibility of Hydrothermal Nitrogen Doping Process for Enhancing Visible Light Photocatalytic Activity of Metatitanic Acid Powder
Authors: Park Se Keun , Woo Ji Eun , Shin Hyun Ho
Published: July 2013

Wide band-gap photocatalyst is active only under UV light irradiation. Nitrogen doping into photocatalyst is able to extend the light absorption to the visible light region, allowing more solar energy to be utilized in photocatalytic applications. The hydrothermal process is widely applied for the preparation of nitrogen-doped TiO2. The hydrothermal method is attractive for its simplicity and environment friendly conditions. Metatitanic acid (MTA) is an industrially available intermediate product in sulfate process for TiO2production, which is mesoporous material with large speciﬁc surface area and pore volume. In this work, MTA powder was hydrothermally treated with three types of nitrogen sources (urea, hexamethylenetetramine, and ammonium hydroxide) and subsequently heat-treated in N2flow. The results of UV-Vis diffuse reflection spectra and XPS show that it is possible to dope the nitrogen dopant into MTA by the hydrothermal process and the post-heat treatment. Higher photocatalytic activity in photodegrading rhodamine B dye under visible light was obtained when processed in ammonium hydroxide (MTA-A), but weaker in the samples of urea (MTA-U) and hexamethylenetetramine (MTA-H).
Preparation of Hematite by Drip Thermal Oxidation Using a Fluidized Bed for Conversion to Electromagnetic-Wave-Absorptive Magnetite
Authors: Nakazato Tsutomu , Iikuma Yoichi , Kai Takami
Published: July 2013

Electromagnetic wave absorbing properties in GHz region were investigated for magnetite prepared by hydrogen reduction of hematite, which was synthesized via drip thermal oxidation using a fluidized bed. The magnetite powder product showed better absorption ability when the precursor hematite was prepared at a higher bed temperature, which also induced an improvement in morphology. This morphological enhancement is believed to result from the rapid thermal oxidation treatment of the hematite powder in the bed along with an accelerated evaporation of aqueous FeCl2 solution.
Simulation Study on HPDC Process for Automobile Part with Aluminum Alloy
Authors: Kwon Hong Kyu , Seo Kwang Kyu
Published: July 2013

In this research, in order to optimize casting design of an automobile part (Gear Box), Computer Aided Engineering (CAE) was performed by using the simulation software (Z-Cast). The simulation results were analyzed and compared with experimental results. During the filling process, internal porosities caused by air entrap were predicted and reduced remarkably by the modification of the gate system and the configuration of overflow. With the solidification analysis, internal porosities caused by the solidification shrinkage were predicted and reduced by the modification of the gate system. For making better permanent High Pressure Die Casting (HPDC) mold, cooling systems on several thick areas are proposed in order to reduce internal porosities caused by the solidification shrinkage.
Synthesis and Characterization of Zeolite from Glass by Hydrothermal Processing
Authors: Tsujiguchi Masato , Kobashi Tadashi , Kanbara Junji , Utsumi Yasuhiko , Kakimori Nobuaki , Nakahira Atsushi
Published: July 2013

Zeolite is a microporous aluminosilicate material with uniform pore size of less than 2 nm and chemical, mechanical, and thermal stability. In general zeolite is synthesized from silica, alumina, mineralizer (alkali metal hydroxide and fluoride) and water. Recently it has been reported that various zeolites is synthesized from soda-lime glass, slag and coal fly ash as silica and alumina source. On the other hand, the production volume of various kinds of high-quality glass which are utilized for high-tech products such as liquid crystal displays and plasma displays is rapidly increasing. The purpose in this study is to synthesize a zeolite from crushed aluminoborosilicate glasses which is used as LCD panels glass substrate. According to the XRD analysis, it was found that the synthesized sample had zeolite related structure. And the results of SEM observation of the products suggest that the zeolite structure was obtained as well as XRD results. It was thought that zeolite was successfully synthesized from the glass by this synthetic processing.
Crystallographic Features of Low-Carbon Bainite Formed under Non-Isothermal Conditions
Authors: Panpurin S.N. , Zolotorevsky Nikolay Y. , Titovets Yuri F. , Zisman A.A. , Khlusova E.I.
Published: July 2013

The effects of cooling rate and austenite structure on bainite formation was investigated by means of electron backscatter diffraction analysis and processing of obtained orientation data. Variant pairing tendency of bainitic ferrite was found to depend on the austenite grain size, austenite plastic deformation and cooling rate. In the bainite formed at low cooling rate the variant pairs having the same Bain axis correspondence are more frequent, while at high cooling rate the variant pairs having the same parallel correspondence of close-packed planes are formed side by side preferably. At the same time, these features are influenced significantly by structural state of parent austenite.
Modelling of Strain Rate and Temperature Dependent Flow Stresses of Supercooled Austenite for AISI 4140
Authors: Schwenk Maximilian , Kaufmann Bernhard , Hoffmeister Jürgen , Schulze Volker
Published: July 2013

The numerical modelling of heat treatment has become an essential tool in understanding distortion potentials for case hardening. When looking at other surface hardening processes such as induction or laser hardening, high heating and cooling rates automatically lead to higher strain rates during the heat treatment cycle. So far, there have been almost no investigations on the strain rate as well as temperature dependency of the mechanical properties of supercooled austenite. In this paper, the typical induction and laser hardening steel AISI 4140 has been used in order to determine the influence of strain rate and temperature on the mechanical behaviour. The experiments are based on tensile tests, using a specifically designed thermo-mechanical simulator. The experimental results show that a positive strain rate sensitivity for strain rates up to 1 s-1 results. Especially in the temperature interval where austenite formation occurs during heating, the strain rate sensitive flow stress might lead to an alteration of the plastic strains in comparison to conventional heat treatments at low heating rates. The material model presented in this paper allows a good reproduction of the experimental data over a wide range of strain rates and temperatures.
Recrystallization Behavior of 0.11% Ti-Added Complex Phase Steel during Hot Compression
Authors: Zhang Mei , Huang Chao Bin , Zeng Wei Ming , Fu Ren Yu , Li Lin
Published: July 2013

Double-hit isothermal deformation and multi-pass continuous cooling hot compression tests were carried out to study the recrystallization behavior of a 0.11 (in mass %) Ti-microalloyed complex phase (CP) steel. The influence of different deforming temperatures and holding times on microstructure evolution was investigated. The results showed that a pronounced austenite grain refinement after appropriate recrystallization process has been detected. The grain size decreases continuously from 176μm to 20μm after four-pass compression. It has been verified that non-crystallization temperature (Tnr) of the experimental steel is about 975°C under the deformation conditions. Based on the stress-strain curves, a kinetic method was established to predict the non-recrystallization temperature of the studied steel during nonisothermal continuous hot deformation.
Microstructure and Mechanical Properties of X80 Induction Heating Bends
Authors: Yang Liu Qing , Liu Yu , Feng Bin , Fan Yu Ran , Yao Deng Zun
Published: July 2013

By using physical thermal simulation technology, combined with metallographic analysis, tensile tests, impact and hardness tests, effects of heating temperature and cooling speed on microstructure and mechanical properties of X80 induction heating bends were investigated. The results show that as the heating temperature rises, TS of X80 induction heating bends increases gradually. However, when the heating temperature rises above 1100°C, plasticity and toughness of the bends begin to decrease, and grain growth tends to be obvious. When the heating temperature is 1050°C, X80 induction heating bends have a good strength and toughness. As the cooling rate increases, strength and toughness of X80 bends are improved considerably. In the cooling rate range between 20°C/s and 30°C/s, the microstructure of X80 bends is mainly composed of polygonal ferrite and granular bainite. Due to the very high dislocation density inside granular bainite and the fine and dispersed M-A constituents, X80 induction heating bends have a very good strength and toughness.
Microstructural Evolution during Tempering of 16Cr-5Ni Stainless Steel: Effects on Final Mechanical Properties
Authors: De Sanctis Massimo , Valentini Renzo , Lovicu Gianfranco , Dimatteo Antonella , Ishak Randa , Migliaccio Umberto , Montanari Roberto , Pietrangeli Emanuele
Published: July 2013

In this work, the structural behaviour during tempering of two different heats of 16Cr-5Ni supermartensitic stainless steel has been studied by means of dilatometry, transmission electron microscopy and X-ray diffraction. A thermomechanical simulator (Gleeble 3800) has been also used to characterize the effects on final mechanical properties of different tempering temperatures in the range 600 °C to 700 °C and the influence of sub-zero cooling on industrial double tempering treatments. It has been found that the pre-existence of retained austenite in as-quenched conditions can induce significant differences in the microstructural evolution during tempering and on the final mechanical properties of industrial components, thus inducing problems in controlling final maximum hardness allowable by normative requirements.
Introduction of Materials Modelling into Processing Simulation
Authors: Guo Zhan Li , Turner Richard , Da Silva Alisson D. , Sauders Nigel , Schroeder Florian , Cetlin Paulo R. , Schillé Jean Philippe
Published: July 2013

The introduction of materials modelling into computer-aided engineering (CAE) processing simulation has become popular in recent years, whereas the fundamental challenge lies in the development of material models that can calculate the properties essential for processing design and simulation. This paper reviews the recent development of such models and the material data that can be calculated include physical, thermophysical, and mechanical properties, as well as phase transformation kinetics. The calculated material data has been used as input to numerous CAE packages for the simulation of casting, welding, forming and heat treatments. Two case studies are presented here, one on the simulation of residual stress in linear friction welding of titanium alloys, and the other on the prediction of distortion and residual stress in heat-treated large steel rings.
Steel Property and Process Models for Quality Control and Optimization
Authors: Tamminen Satu , Tiensuu Henna , Juutilainen Ilmari , Röning Juha
Published: July 2013

High quality and low variability in the properties of the products are the main goals in manufacturing. The quality of the product is verified by testing different properties. It can be improved with models developed for event prediction. This paper presents with application examples the modelling steps required for effective process modelling. First, the pre-processing and feature extraction phase are illustrated. The modelling phase concentrates especially on the heteroscedasticity problem that is commonly present in industrial applications. The process monitoring and control parameter optimization based on these models is presented, as well as the solution for the lack of observations for the dependent variable. Many of the developed models are in daily use in different process states in steel industry. They enable the design of new products and the analysis of the effects of different process parameters on variability reduction. The proposed methods are application independent.
Numerical Simulation of Temperature Field during Vacuum Sublimation Purification of Metal Tm
Authors: Zhang Xiao Wei , Miao Rui Ying , Wang Zhi Qiang , Li Zong An
Published: July 2013

The thermo physical parameters of Tm vapor and the range of sublimation temperature have been determined by vapor pressure of metal Tm, and a 2-D axis-symmetric heat transfer model has been developed to investigate the temperature distribution in sublimation furnace. The simulation results show that, due to the heat loss at crucible bottom, the temperature of crucible, solid metal and Tm vapor increases with crucible height increasing, reaches the maximum value in the middle of crucible in height direction, and then decreases rapidly, and the maximum temperature is closer to the heating body temperature with its increasing; at the outside surface of condenser, the temperature decreases sharply, and the temperature curves with various heating body temperature are almost overlapped, the condensing region of Tm vapor is not affected by the heating body temperature; the temperature of upper surface of solid Tm is about 30°C lower than that of heating body, and the absolute and relatively temperature differences decrease correspondingly with increasing of heating body temperature.
Numerical Investigation on Void Nucleation around Inclusions under Combined Mechanical and Thermal Cycling Conditions
Authors: Jin Cheng , Shi Chun Yuan , Li Guan Lin , Niu Ji Tai
Published: July 2013

In this paper a numerical investigation on the void nucleation behaviors under combined mechanical and thermal cycling conditions have been performed. A finite element unit cell model is conduct to calculate the local stress-strain field and describe the process of void nucleation from inclusion. Numerical results show that the thermal mismatch stress between the particles and matrix can assist the external load to cause interface debonding. Under certain mechanical and thermal cycling conditions, complicated stress and strain hystereses developed in the matrix. Both the plastic strain and plastic energy density of the interface will be accumulated during every thermal cycle. The plastic energy accumulation of the interface will first reach the debonding value and failure occurs. Based on the numerical calculation, a new energy based failure criteria is proposed to characterize the behaviors of void nucleation under combine mechanical and thermal cycling conditions.
Optimization of Local Laser Heat Treatment Process Using a Simple FE-Model
Authors: Järvenpää Antti , Kiuru T. , Määttä Antti , Jaskari Matias , Mäntyjärvi Kari
Published: July 2013

Local laser heat treatment is an efficient method to manufacture tailored heat-treated steel strips. It can be applied to soften narrow zones of the strip in order to improve its formability on desired areas. However, the properties achieved are dependent on several process parameters. An objective is to develop a predictive model to optimize the heat treatment parameters instead of using experimental trials. In the present study, a finite element model was applied to predict the maximum temperature and heating and cooling rates, as well as the heat distribution along the heat treated area. To develop the model and to test its feasibility, experiments were performed, in which process parameters were varied to study their effects on temperature distribution in a 6 mm thick abrasion resistant steel grade. Scanning of a laser beam was used to optimize the width and depth of the heat-affected zone.In practice, local laser heat treatment process parameters have to be optimized with care for successful results. The most important task is to minimize the temperature gradient between the surfaces and to keep the peak temperatures close to the austenitizing temperature. The results indicate that a simple model can be used to predict the outcome of the heat treatment, so that finite element modeling can be adopted as a suitable tool for design of local heat treatments, allowing more advanced treatments and applications with complex geometries.
Precipitation Processes in High-Manganese Steels
Authors: Paul Georg , Khlopkov Kirill
Published: July 2013

The highly interesting properties of high manganese steels can be further improved by microalloying. The introduction of carbon-nitride precipitates improves the yield strength and the microstructural control during the production process. Due to the high manganese content in these austenitic steels significant changes in the precipitation behaviour have to be expected in comparison to conventional carbon-manganese steels. However, although crucial for steel design, this has not been systematically described before. Preliminary results showing the effect of Nb and V are presented. Namely the softening behaviour is related to the precipitation state. In summary this allows describing the precipitation-time-temperature evolution and provides the necessary background for the alloy and process design.
Study on Cyclic Strain Localization and Fatigue Fracture Mechanism in High Manganese Twinning-Induced Plasticity Steels
Authors: Hamada Atef S. , Porter David A. , Puustinen Jarkko , Karjalainen L. Pentti
Published: July 2013

The fatigue cracking mechanisms of two high Mn TWinning-Induced Plasticity (TWIP) steels are investigated in detail using electron channelling contrast imaging (ECCI) and electron backscatter diffraction (EBSD). Furthermore, the fracture surfaces of the fatigued steels have been studied by employing a field emission gun scanning electron microscope (FEG-SEM). The fine details of the fatigued surface topography are verified using an atomic force microscope (AFM). The results indicate that the fatigue crack embryos nucleate at an early stage of the fatigue life as a result of local straining at grain and annealing twin boundaries at sites, where persistent slip bands create dislocation piled-ups that impinge on boundaries. The EBSD measurements showed that unlike in monotonic straining, the formation of deformation twins is not observed under cyclic straining.
Simulation Study on the Influence of H2 on the Carbon Deposition in ICVI of Thick-Walled Perform
Authors: Xu Peng , Liao Dun Ming , Zhou Jian Xin , Pang Sheng Yong
Published: July 2013

A two dimensional model was employed to simulate the densification process of thick-walled hollow cylinder preform of C/C composite. Using the hydrogen inhibition model, carbon deposition processes under different partial pressures were compared and the efficiency of densification was analyzed. Then the density distribution of some definite time was analyzed to explain the mechanism of hydrogen inhibition. The results showed that with the adjunction of hydrogen, density distribution in preform was improved while the deposition process took a longer time.
Physical Simulation of Weldability of Weldox 1300 Steel
Authors: Węglowski Marek Stanislaw , Zeman Marian , Lomozik Miroslaw
Published: July 2013

In the present study, the investigation of weldability of new ultra-high strength - Weldox 1300 steel has been presented. The thermal simulated samples were used to investigate the effect of welding cooling time t8/5on the microstructure and mechanical properties of the heat affected zone (HAZ). In the frame of these investigation the microstructure was studied by the light (LM) and transmission electron microscopies (TEM). It has been shown that the microstructure of the Weldox 1300 steel is composed of tempered martensite, and inside the laths the minor precipitations mainly V(CN) and molybdenum carbide Mo2C were observed. Mechanical properties of parent material were analysed by the tensile, impact and hardness tests. In details the influence of cooling time in the range of 2,5 - 300 s. on hardness, impact toughness and microstructure of simulated HAZ was studied by using welding thermal simulation test. The results show that the impact toughness and hardness decrease with the increase of t8/5under the condition of a single thermal cycle in simulated HAZ. The continuous cooling transformation diagrams (CCT-W for welding conditions) of Weldox 1300 steel for welding purposes was also elaborated. The steel Weldox 1300 for cooling time in the range of 2,5 - 4 s showed martensite microstructure, for time from 4 s to 60 s mixture of martensite and bainite, and for longer cooling time mixture of ferrite, bainite and martensite. The results indicated that the weldability of Weldox 1300 steel is limited and to avoid the cold cracking the preheating procedure or medium net linear heat input should be used.
Physical and Numerical Simulations of the Microstructure Evolution in AA6082 during Friction Stir Processing by Means of Hot Torsion and FEM
Authors: Krumphals Friedrich , Gao Zeng , Zamani Hassan , Mitsche Stefan , Enzinger Norbert , Sommitsch Christof
Published: July 2013

A reproduction of the conditions occurring during friction stir processing, where a fine grained structure according to the process parameters rpm, transverse speed and pressure develops is the main focus in the present work. To physically simulate such a friction stir process, hot torsion tests at constant temperatures were carried out in a Gleeble ® 3800 machine at different strains and strain rates. The specimens were immediately water quenched after hot deformation to avoid any static recrystallization. The microstructure was investigated to characterize the grain size evolution and misorientation as a function of the local strain, strain rate and temperature. Dynamic recovery was observed followed by continuous dynamic recrystallization at large deformations. By means of DEFORMTM3D the occurring strain, strain rate and temperature distributions, which are decisive for the observed microstructure evolution, were evaluated.
Development of Predicted Stress and Strain during Conventional and after Mitigation of Welded Aluminium-Manganese Alloy
Authors: Soul F. , Ateeg M.
Published: July 2013

The trend in automotive, aircraft, and marine industries is the increasing use of sheet materials to reduce weight in components and optimize materials performance. Welding is the main fabrication and assembly process in many of these industrial applications. However, in using thin-shell structures in such applications, welding may results in significant residual stresses and out-of-plane distortion. Transient thermal stresses, residual stresses, and distortion sometimes cause cracking and mismatching of joints. High tensile residual stresses are undesirable since they can contribute to fatigue failure. The analysis and measurement of temperature and stresses in component are often too complex to conduct in practise, and thus finite element models provide feasible approach to examine these matters. In this paper, finite element analysis has been performed using the ANSYS package to study the behaviour of longitudinal residual stress and strain in a welded thin aluminium-manganese alloy. The model presented simulates conventional welding and welding with the introduction of welding mitigation technique for enhancement of heat transfer, in which a trailing heat sink was applied. The thermal profiles obtained using the mitigation technique is completely different from those obtained in the conventional cooling. The localized transient residual stress and through-thickness strain after applying a cooling sink are discussed. The transient residual stress behaviour was highly affected by the modified temperature distribution and magnitude due to introducing the heat transfer enhancement.
Characterizing the Decomposition of Ti2AlC during its Brazing with Cu by Using Ag-Cu Filler Alloy
Authors: Wang Guo Chao , Zhang Jie , Liu Xiao Wen
Published: July 2013

The reaction process between Ti2AlC and Ag-Cu filler alloy was mentioned in our previous study. However, the reaction mechanism between Ti2AlC and filler alloy remained uncertain due to the existence of TiAl2, which was widely distributed in the dual-phase Ti2AlC substrate and exhibited intense reaction with Cu. In current research, pure-phase Ti2AlC was brazed to Cu using Ag-Cu filler alloy respectively at 850°C and 900°C for 10 min. First of all, to investigate the influence of TiAl2 on clarifying the reaction mechanism, Ti2AlC substrates with different component (single phase and dual phase) were joined to Cu at 850°C for comparison. However, in these joints, it was difficult to find any other reactant except for AlCu2Ti. Thus, the pure-phase Ti2AlC was brazed to Cu at 900°C, aiming to intensify the interaction between substrates and filler alloy. For characterizing the microstructure evolution in the joint, the typical region of the joint that contained all the reactants was selected and sliced by focused ion beam technology. Combining with transmission electron microscopy, all the decomposition products (e.g. Ti3AlC2 and TiC) in the joint were identified. Then the decomposition mechanism of Ti2AlC was clearly disclosed.
Effect of Friction and Lubrication on Formability of AA5182 Alloy in Hydroforming of Square Cups
Authors: Modi Bharatkumar , Ravi Kumar Digavalli
Published: July 2013

nfluence of friction and lubrication on formability of an aluminium alloy (AA5182) in hydroforming of square cups has been studied experimentally and numerically. Three friction conditions were created at the blank-die interface using hydraulic oil, Teflon and dry condition (no lubrication). Maximum thinning and minimum radius at the cup corners were taken as criteria for formability evaluation. Formability improved to a great extent with Teflon sheet as the lubricant. Lower friction allowed better draw-in of the material with higher uniformity of strain distribution and the maximum pressure that the material can sustain has significantly increased.
Numerical Simulation of Multiple-Step Incremental Roll-Bending Forming of a Large Metal Sheet to U-Shape
Authors: Hu Da Chao , Li Guo Qing , Fu Ze Min
Published: July 2013

Simulation of multiple-step incremental roll-bending forming and springback of large-scale sheet metal with U shape was implemented in this paper using ABAQUS. In view of the semi-ellipse shape of work piece, a geometric plan using fives arcs with different radius to approach the original shape in piecewise is proposed. On the basis of the programming, reasonable arrange the rolling steps, adjust the parameters in ABAQUS. The largest error of curvature radius of different arcs is less than 5% after simulation of the sheet metal forming according to optimized process fitting with Origin8.0. The results show that the incremental roll-bending method forming the semi-ellipse shape work piece is feasible.
Signal Processing Method (HT and HHT) of AE for Complex Fault Detection
Authors: Ha Jeong Min , Lee Jong Myeong , Lee Jeong Hoon , Gu Dong Sik , Choi Byeong Keun
Published: July 2013

In the signal processing method, envelope analysis is a useful method to evaluate the rolling element bearing problems and Wavelet transform is a powerful method to detect faults occurred on gearboxes. However, exact method for AE signal is not developed yet. Therefore, in this paper, two methods, which are Hilbert Transform (HT) and Hilbert-Huang transforms (HHT), will be compared for development a signal processing method for early fault detection system by using AE. HHT has better advantages than HT because HHT can show the time-frequency domain result. But, HHT needs long time to process a signal, which has a lot of data, and has a disadvantage in de-noising filter.
Fatigue Life Prediction of Stainless Steel Laser Lap Joints Based on Natural Frequency Changes
Authors: Shi Chun Yuan , Zhan Lan , Wang Hong Xiao , Wang Chun Sheng , Yang Wei
Published: July 2013

In this paper, fatigue damage and life prediction of laser lap joints were investigated based on natural frequency as the damage variable. At each fatigue stage, damage degree of laser welded specimen was monitored by the fatigue test and dynamic response tests. The results show that in the fatigue process during the increase in the number of fatigue cycles, each order natural frequency of test specimen decreased at different rate. There was almost no damage before the number of cycles reached 60% of the fatigue life, and then cracks began to initiate. When the number of cycles reaches 80% of the life, macroscopic cracks appeared and the predicted damage degree reached to 50%. Based on relation between the change rate of the natural frequency and the fatigue damage, a new fatigue life prediction model was established. The results from experimental tests were consistent with the fatigue life prediction model.
New Continuous Casting and Slab Tracking Simulators for Steel Industry
Authors: Louhenkilpi Seppo , Laine Jukka , Miettinen Jyrki , Vesanen Risto
Published: July 2013

Research group of Metallurgy at Aalto University has been developing simulation models and tools for continuous casting since from the early 80s. The main models developed are the heat transfer model, DYN3D, and the solidification and microstructure model IDS. The models have been further developed and integrated to a continuous casting simulator and to a slab simulator. The continuous casting simulator calculates the important phenomena taking place in the strand during casting and the slab simulator calculates the phenomena taking place in the slabs when they are transferred from caster to reheating furnace. The numerical solution algorithms in the simulators are so fast that they can be used in on-line applications. The simulators have today many new options as hydrogen removal and quality prediction modules. In this paper, the simulators and their modules are presented.