International Journal of Microstructure and Materials Properties (22 papers in press)
Early-age Concrete Strain Error Detecting Method under Continuous Temperature Change
by Fang Yu
Abstract: The stiffness of concrete members and the free energy of material degenerate under the continuous temperature change, and the strain error exists. In order to solve the above - mentioned problems , Early-age Concrete Strain Error Detecting Method under Continuous Temperature Change is proposed.Through accurate measurement of concrete strain error, the nonlinear creep model of early age concrete structure under continuous temperature change is deduced. The coupling relationship between material stress and creep is quantitatively analyzed to improve the strength of concrete. A method for detecting early age concrete strain error under continuous temperature change based on concrete splitting tensile strength microscopic analysis and low cycle fatigue test is proposed. The nonlinear relationship model of concrete strain amplitude and the number of fatigue cycles under continuous temperature is established. Considering constraint parameters of concrete such as buckling, fatigue and strength, concrete constitutive model is constructed. The ratio of concrete strength degradation value to the initial peak stress is plastic strain index for strain amplitude uploading and concrete deformation modulus nonlinear creep relation modulus with loading age is analyzed. The concrete compression test is carried out by concrete splitting tensile strength micro-analysis method. The low-cycle fatigue test is used to achieve concrete strain error detection. Test results show that the method used to detect early age concrete strain error under continuous temperature change has better reliability and strain error test results and experimental results are in good consistency.
Keywords: Continuous temperature variation; Early age concrete; Splitting tensile strength; Strain; Fatigue; Strength.
Evaluation of the impact of temperature distribution on the degradation process of bituminous pavements : Thermal non-destructive approach.
by Abdelilah Bannour
Abstract: The originality of this study resides in taking into account the effect
of the heat flux, the surface layer thickness and the rate of voids in the interface
on temperature distribution within surface course. In this work, a numerical
simulation was performed, which aim at studying the amplitude of the temperature
distribution differs under the effect of the variation of the heat flux, the variation
of the thickness of the surface layer and the rate of voids in the interface. The
numerical simulation carried out to determine the effect of each of these factors,
showed that the distribution of the temperature remains very sensitive to the
increase of the flux but the influence of the other two factors less significant.
The contribution of this work proposes a means of helping pavement engineers
to design structures with excellent performance that are much more resistant to
temperature fluctuations throughout the pavement life span.
Keywords: Thermal non-destructive testing; Flexible pavement; Road deterioration; Numerical simulation; Finite elements; Temperature.
Low-temperature synthesis and characterization of its photocatalytic properties of BiNbO4 by combustion method using polyvinyl alcohol
by Bac Nguyen, Nhiem Dao, Dung Doan, Chuc Pham, Chi Nguyen, Lim Duong
Abstract: BiNbO4 nanopowders were synthesized by polyvinyl alcohol sol-gel combustion method using freshly starting material Nb2O5. nH2O. The prepared samples were characterized by X-ray diffraction, field-emission scanning electron microscopy, transmission electron microscopy and thermal gravimetric and differential thermal analysis. The orthorhombic single phase calcined at 750oC for 2 hours in the air was thoroughly studied with the highest photocatalytic properties in 25 nm average size. Methyl orange was used to evaluate the photocatalytic properties of BiNbO4 under the visible light irradiation which was degraded by 98%. The regeneration ability of the catalyst was reduced by only 1.65% from 98.85% to 97.20% after using four-times without recovery.
Keywords: BiNbO4 nanopowders; combustion method; methylene orange degradation; polyvinyl alcohol.
Study on Bayer Digestion Behavior of Low Grade Bauxite with High Sulfur
by Xuejiao Zhou, Yongli Chen, Jianguo Yin, Wentang Xia, Xiaoli Yuan
Abstract: Low grade bauxite with high sulfur is rich in nature but difficult to be applied industrially. Sulfur in bauxite leads to a series of remarkable negative effects in Bayer process. This work is focused on the dissolution behavior of sulfur, iron and aluminum from a low grade bauxite. The process parameters such as holding time, alkali concentration and temperature were optimized. Scanning electron microscope, X-ray diffraction and X-ray fluorescence were used to characterize the morphology, phase and composition of the bauxite and residue. The results indicate that the relative digestion rate of aluminum can approach to 75%. The increase in iron digestion rate enhances the sulfur digestion rate, enlightening us that it is possible to remove sulfur and iron simultaneously by the seed precipitation for high sulfur bauxite. This research is a novel technical support and theory guidelines for utilizing the low grade bauxite with high sulfur.
Keywords: low grade bauxite with high sulfur; Bayer digestion; dissolution rate; simultaneous removal of sulfur and iron.
Processing of PA2200/HDPE by SIS: Effect on Microstructure and Mechanical properties
by SAGAR BALIGIDAD, Chandrashekar U, Elangovan K, Shankar S
Abstract: Application of polymer blend offers advantages like controlled composition, free-form structure and better operating parameters for rapid prototyping (RP) of parts. This study focuses on the investigation of parts produced by using different blend ratios of PA2200/HDPE and by selective inhibition sintering (SIS) technique. Study includes evaluation of blend ratios and the influence of operating parameters on the density, mechanical properties and the microstructure of the generated parts. Microstructure of parts produced with differing PA2200/HDPE blends have been found to be heterogeneous with co-continuous and disperse phase, depending upon the percentage of HDPE in the blend. Part-density and porosity of 3D printed parts also varied as a function of the blend composition. The blends 80/20 and 50/50 showed poor ultimate strength, indicating a low likeliness between PA2200 and HDPE components. The 20/80 blend showed higher ultimate strength due to high HDPE content. It also discloses a change in creep behavior as a function of change in polymer composition.
Keywords: PA2200/HDPE blend; Selective Inhibition Sintering; density; Mechanical Properties; Microstructure,.
Optimization of Forging Parameters of 35C8 Steel Using Grey Relational Analysis
by Md Israr Equbal
Abstract: In metal forging operations desired microstructures with optimum mechanical properties of the forged part is really a tedious job. The microstructures, as well as the mechanical properties, depending on many process variables either directly or indirectly. The significant influence of the process parameters may be different for different responses. This study involves investigation of the optimal set of process parameters such as forging temperature, percentage deformation and cooling rate in hot forging of commercial medium carbon forging steel (AISI 1035). All forgings have been completed in between flat dies of 150 ton hydraulic press. To reduce the number of experimental runs Taguchis L9 (34) orthogonal array was used. Analysis of variance (ANOVA) is employed to determine significant parameters. Response tables and graphs were used to find the optimal levels of parameters. Empirical models have also developed relating response and process parameters. Based on the experiments conducted on L9 orthogonal array, analysis has been carried out using the Grey Relational Analysis, a Taguchi method. The confirmation experiments were carried out to validate the optimal results. The mechanical properties obtained have been correlated with microstructures using a high magnification optical microscope.
Keywords: Metal forging; Microstructure; Orthogonal array; ANOVA; Grey relational analysis.
Experimental Investigation of Mechanical Properties of High-Temperature Ni-Based Super alloy by Varying The Wt. % of Aluminum
by Mohan Kumar Pradhan, Amar Pradhan
Abstract: Superalloys are widely used in many advanced industries due to its strength and resistance to oxidation at elevated temperature. The objective is to prepare a Ni-based superalloy with three different Al wt %, and the effects Al element on the oxidation behavior was studied under the high-temperature condition at 950 ◦ C in dry air isothermal oxidation test. X-ray diffraction and scanning electron microscopy technique swereused to study the micro-structures. as wt. % of Al increases from 5 to 6 it promotes the γ phase precipitate, which directly increases the volume fraction of γ phase in the microstructure of superalloy which enriches Al cativity and stimulates continuous Al 2 O 3 protection layer to increase oxidation resistance of the alloy. Further compressive strength and micro Vickers hardness of the three samples are also tested. With the Al wt. %increases from 5 to 6 mechanical properties increase significantly.
Keywords: Super alloy; Mechanical Properties; Oxidation; Micro-structure,rnSEM; XRD.
Study on High Temperature Collapse Detection Technology of Reinforced Concrete Columns Strengthened with Angle Steel
by Fang Yu
Abstract: Reinforced concrete column strengthened with angle steel has strong high temperature resistance. Through the quantitative analysis and testing of the high temperature collapse of concrete column, the formula design of reinforced concrete column is improved to enhance the high temperature collapse performance of concrete column. Reinforced concrete columns high temperature collapse technology strengthened by angle steel based on bilinear elastic hysteretic model is proposed and equivalent linear recursive analysis method is used to calculate the restoring force model of concrete column. The lateral load and yield strength analysis of angle steel reinforcement are analyzed by three-linear hysteresis model. The foundation shear force stiffness model of reinforced concrete column under different loads is constructed and the relationship between temperature and collapse fatigue fracture under bilinear elastic hysteresis mechanics model is modeled to achieve high temperature collapse detection. Experimental results show that the method can be used to calculate the ultimate crack depth and fracture toughness reliability of concrete column and detect high temperature collapse of reinforced concrete columns. It can be effectively combined with regular field nondestructive testing and long-term strain monitoring to achieve high temperature collapse of concrete column detection.
Keywords: Angle steel reinforcement; Reinforced concrete column; Collapse detection.
A case study of mechanical and metallurgical properties of friction stir welded AA6063 AMC
by NARINDER KAUSHIK, Sandeep Singhal
Abstract: This experimental work deals with the comparative examination of microstructural and mechanical properties of as cast and friction stir welded, AA6063/SiC matrix composite. AA6063/10.5 wt. % SiC aluminum matrix composite was produced by employing stir casting route. Specimen Plates having thickness 6mm were cut from the fabricated composite matrix and friction stir welded successfully. The FSW was performed by using a tool rotational rate of 1400 rpm and tool transverse rate of 124 mm/min. A square pin profiled tool made of AISI H13 tool steel was used. The microstructural study revealed that FSW produced a notable reduction in the size of reinforcement agents and their homogeneous distribution in the stir zone as compared to the base metal composite matrix. Frictional heat generated during FSW had impacts on the growth, dissolution and reprecipitation of the hardening precipitates. The microstructural changes resulted in improved mechanical properties. The SEM fracture analysis revealed that the fracture behavior was changed from ductile to brittle after FSW.
Keywords: FSW; AMC; AA6063; Microstructure; Mechanical properties; Tensile strength; Microhardness; Fracture.
Factors Affecting Properties of High Strength Geopolymer Concrete Cured at Ambient Temperature.
by Aslam Hutagi, Rajasab Khadiranaikar
Abstract: This paper experimentally investigates the factors affecting properties of high strength Geopolymer Concrete using low calcium fly ash and granulated blast-furnace slag. The aim is to produce high strength geopolymer concrete with ambient curing and to study its properties in the fresh and hardened state. Effect of ground granulated blast-furnace slag, alkaline liquid, water-binder ratio and molarity on workability and strength are studied. Ground granulated blast-furnace slag content is varied from 0% to 40 % of the total binder with sodium silicate to sodium hydroxide ratio 2.5. The molarity of the solution was 14M and 16M. Activator content 30%, 35% and 40% of total binder. Increases in strength were observed in geopolymer concrete with higher ground granulated blast-furnace slag ratio in the mix. Fly ash is replaced by 40% ground granulated blast-furnace slag to achieve compressive strength of 77 MPa.
Keywords: geopolymer concrete; strength,GGBFS; alkaline liquid; water-binder ratio and molarity.
Micro-magnetic response of friction stir welded steel plate at various magnetizing frequency and magnetic field intensity
by Avinash Ravi Raja, Meghanshu Vashista, Mohd Zaheer Khan Yusufzai
Abstract: The research goal of present experimental work was to analyze the variation in magnetic response (at different magnetizing frequency and magnetic field intensity) of IS-2062 steel of grade B upon friction stir welding. Tungsten carbide tool having 15 millimeter shoulder diameter was used to weld the steel plates having 3 millimeter thickness with welding speed of 150 millimeter per minute and revolving speed of 800 revolutions per minute.Welded steel plates were characterized using Barkhausen Noise analyzer. Magnetic response of material, before welding and after welding was recorded in terms of Barkhausen Noise signal parameters that are root mean square value of signal and number of pulses. Both the signal parameters was observed to correlate well with grain refinement and changes in micro-hardness upon friction stir welding of steel at different analysis parameters such as magnetic field intensity and excitation frequency.
Keywords: Friction Stir Welding; Barkhausen Noise analysis; Microstructure; Micro-hardness.
Morphological behavior of Carbon/Carbon and Carbon/Carbon-Silicon Carbide composites under reciprocating sliding conditions against uniphase and multiphase material
by Parshant Kumar, Vijay Kumar Srivastava
Abstract: The goal of this paper is to assess the variation in morphological behavior of carbon/carbon and carbon/carbon-silicon carbide composite under reciprocating sliding against uniphase and multiphase substrates with variation of normal load. Chrome steel was chosen as uniphase and carbon/carbon and carbon/carbon-silicon carbide composites were slid in self and complementary mated pairs for multiphase materials. The worn surfaces were analyzed under scanning electron microscope. Morphological study of worn surfaces showed that carbon/carbon composites slid against chrome steel didnt show much abrasion whereas carbon/carbon-silicon carbide composites showed abrasion and, hard silicon carbide particles abraded the formed friction film. In self-mated pairs, carbon/carbon composites mainly showed delamination wear, and carbon/carbon-silicon carbide composites primarily showed matrix peeling and abrasion. In complementary mated pairs, carbon/carbon composites generated some wear debris with sharp edges. The abrasion and adhesion of carbon/carbon-silicon carbide composite were very less in case of complementary mated pair.
Keywords: Morphology; Dry sliding; Surface; Ceramics; Fibers; Composites; Carbon; Silicon carbide; Delamination; Adhesion; Abrasion.
Influence of Fe on the Microstructure and Mechanical Properties of Low Al-SI Alloys
by Oscar Sotomayor, Carlos Diaz, Antonio Pancho
Abstract: The present study investigates the influence of iron (precipitation of Fe-rich phases) on microstructure, ultimate tensile strength, elongation after fracture and hardness of the aluminum alloy A356, for which metallographic analysis and testing of mechanical properties were performed for iron weight percentages of 0.5, 0.8 y 1%. Phases identification was carried out by X-ray diffraction, which revealed the precipitation of β iron intermetallic phase of stoichiometry 〖Al〗_5 FeSi and monoclinic crystal structure. Cooling rate (0.45 °C / s) for sand mould was calculated through secondary dendrite arm spacing whose average length was 62.75μm. Microhardness measurements showed the hard nature of the β phase, which produced a general increase on the alloy’s hardness. The tensile strength reduced slightly (~11% for 1 wt. % Fe) unlike the fracture elongation (ductility) which suffered greatly reduces with iron increase (~ 54% for 1 wt. % Fe).
Keywords: Fe influence on AL, β phase, A356.
Special Issue on: Induction Heating and Heat Treatment
Computer simulation of single frequency induction surface hardening of gear wheels: analysis of selected problems
by J. Barglik, A. Smagór, A. Smalcerz
Abstract: Induction surface hardening of gear wheels is a complex technological process making possible to obtain a thin hardened surface zone of the tooth and to keep soft their internal part. Mathematical modelling of the process is still a serious challenge. It requires triply coupled simulation of non-linear, transient physical fields mostly in 3D formulation. The paper deals with the analysis of various factors influencing on accuracy of computations including material properties, heat transfer parameters and modified values of critical temperatures. The main goal of the paper is to evaluate an influence of three material properties: electric conductivity, specific heat and thermal conductivity on the accordance between computations and measurements. Exemplary investigations are provided for the single frequency induction hardening of gear wheels made of steel 41Cr4.
Keywords: induction surface hardening; material properties; coupled problems; modified upper critical temperatures; austenitisation.
Modelling and optimisation of electromagnetically coupled solid manufacturing processes
by F. Bay, J. Alves, J. Barlier
Abstract: Electromagnetically-coupled manufacturing processes cover a wide range of applications - such as magnetic pulse forming processes or induction heat treatment processes. This paper presents a computational model and numerical tool developed in our laboratory for modelling these processes taking into account their specificities.
Keywords: computational modelling; finite elements; multiphysics couplings; process optimisation; electromagnetic couplings; induction heating processes; magnetic pulse forming processes; heat transfer.
Numerical modelling of industrial scale high frequency welding of cladded pipes
by Wladimir Ebel, Martin Kroll, Alexander Nikanorov, Egbert Baake
Abstract: The aim of this work is to develop a model to simulate the high frequency (HF) welding process for cladded pipes and to find process parameters to solve the inconvenient power proportion between the cladding layers. A 2D model of HF pipe or profile welding was created. This model considers the most important parameters of the longitudinal HF-welding process of thin walled cladded pipes. Effects of welding speed, current frequency and material properties have been examined. The material combination of the metal sheets contains S235 as the carrier material and the corrosion resistant alloy 625 for the inner tube cladding. The results have been compared to an available experiment and to gain the basic validation of the model. An approach is proposed to facilitate high frequency welding of cladded pipes under consideration of industrial requirements for a chosen material combination.
Keywords: cladded material welding; profile welding; high frequency welding; induction welding; longitudinal pipe welding; longitudinal profile welding; S235; alloy 625; continuous pipe production; divergent compounds welding; electric resistance welding.
Optimal design of inductor addressed to a tailored heating forging process
by M. Baldan, T. Steinberg, E. Baake
Abstract: Present work's research goals concern the investigation of optimal inductor design for induction heating applied to a 'tailored' heating forging problem. The first part of this paper shows the advantages of adopting a 'tailored' inductive heating, compared to a homogeneous one. In addition to a significant simplification, results of simulation have shown that it is possible to save energy and enhance the overall efficiency. The developed model was then experimentally validated and used for a more rigorous inductor design. The aim of the second part in fact, is to perform an optimisation procedure in order to design an inductor able to provide the desired 'tailored' temperature profile.
Keywords: tailored heating; inductor optimal design; energy saving; induction heating; open die forging.
Three-criteria numerical optimisation as a base for designing induction mass heating
by Yu Pleshivtseva, E. Rapoport, B. Nacke, A. Nikanorov, P. Di Barba, E. Sieni, M. Forzan, S. Lupi
Abstract: The work contains the results of the researches carried out by the authors during past years in the field of multiple-criteria optimisation of induction heaters' design based on numerical coupled electromagnetic and temperature fields' analysis. The main goal of the studies is the application of different optimisation methods and numerical finite element method (FEM) codes to solve the multi-criteria optimisation problems formulated mathematically in terms of the typical optimisation criteria: maximum temperature uniformity, minimum heating time, maximum energy efficiency and minimum scale formation. Standard genetic algorithm, non-dominated sorting genetic algorithm NSGA-II, migration NSGA algorithm, and alternance method of the optimal control theory are applied as effective optimisation tools in practically oriented applications. The developed optimisation procedures are planned to be used for solving the wide range of real-life problems of the optimal design and control of different induction heating devices and systems.
Keywords: multi-objective optimisation; design; induction heating; genetic algorithm; NSGA-II; MNSGA-II; alternance method; optimal control theory.
Milliseconds pulse induction hardening
by A. Aliferov, M. Forzan, S. Lupi
Abstract: This paper presents a technology that allows a fast surface induction hardening of workpiece of relative small dimension by means of a single current shot. This technology was proposed already in 50's but at that time the availability of power converters limited its industrial application to the hardening of very small surfaces. Nowadays, the process can be applied in automotive industrial applications thanks to the availability of power converters in the megawatt range. Pulse induction hardening process is characterised by high power densities, heating times in the range of tens to hundreds of milliseconds and cooling rates attained by self-quenching without the use of external quenching means. In the paper, authors give some practical diagrams for the preliminary definition of the heating parameters that could help the design of this type of process.
Keywords: induction hardening; numerical methods; pulse discharge.
ELTA 7.0 program for induction heat treatment of gears
by Vladimir Bukanin, Alexander Ivanov, Alexei Zenkov
Abstract: Induction heat treatment of gear is a very complicated technology and needs to be investigated in detail. A great deal of researches using experimental methods and 3D computer simulation has been carried out to obtain required mechanical properties of steel. In order to perform these tasks more efficiently the authors offered to use a new version of ELectro-thermal analysis (ELTA) with a special Gear Application. An idea of 2D gear model, methods and structure of program is described. ELTA 7.0 can calculate integral parameters of inductor and temperature in the cross-section of gear for heating and cooling stages simpler and faster than in the case of 3D simulation. Several examples of induction hardening with single and double variable frequencies of power source are presented.
Keywords: gear hardening; induction heating; cooling diagram; ELTA 7.0 program.
Induction clamping of high-revolution tools by rotation in a system of unmovable permanent magnets
by Václav Kotlan, Pavel Karban, Ivo Doležel
Abstract: An alternative way of induction clamping is described, consisting in heating of the sleeve by its rotation in static magnetic field generated by suitably arranged permanent magnets. The most important dimensions of the heating system are optimised with the aim to reach the required increase of the bore of the clamping head at the highest possible efficiency and shortest time of heating.
Keywords: induction clamping; induction heating; finite element method; optimisation techniques; electromagnetic field; temperature field; numerical analysis.
Technologies advancing scan and single-shot induction hardening capabilities
by Collin Russell
Abstract: This paper presents recent inverter and inductor innovations that have advanced the performance and capability of modern scan and single-shot induction hardening equipment. The physics and critical design elements of both of these induction heat treatment processes are discussed in detail and practical case studies featuring numerical computer simulation are referenced throughout.
Keywords: induction heat treatment; scan hardening; single-shot hardening; computer simulation.