bluuebunny/crossref_metadata_2025 huggingface dataset:
Enjeux et limites de la professionnalisation d’un groupe « minoritaire » : les éducatrices de jeunes enfants (EJE)
Authors: Hilbold Mej
Published: November 2016

Dans un contexte de travail massivement féminisé, minorisé, invisibilisé, les professions de la petite enfance ont à lutter contre des représentations de métiers féminins exercés « naturellement » par des femmes, fréquemment pensées comme figures maternantes, tirant essentiellement leurs compétences d’expériences relevant de la sphère privée. Leur arme historique contre ces représentations est leur « professionnalisation» - une professionnalisation pensée ici comme processus de subjectivation - , qui passe aujourd’hui, pour certaines catégories comme les éducatrices de jeunes enfants, par une formation au management d’équipe. La valorisation des professions doit-elle fatalement passer par une normalisation ? Comment cette profession se trouve-t-elle altérée sa professionnalisation ? Cet article s’appuie sur des données empiriques récoltées auprès de personnels de crèches collectives et d’étudiants et formateurs en centres de formation pour éducateurs de jeunes enfants (observations ethnographiques et entretiens non-directifs) et se caractérise au plan théorique par l’examen critique de la sociologie des professions éducatives au prisme des études de genre.
Formability of AA6082-T6 at Warm and Hot Stamping Conditions
Authors: Luan Xi , El Fakir Omer , Gao Hao Xiang , Liu Jun , Wang Li Liang
Published: November 2016

Forming limit diagrams (FLDs) of AA6082 at warm/hot stamping conditions were determined by using a specially designed test rig. The tests were carried out at various temperatures from 300 to 450°C and forming speeds ranging from 75 to 400 mm/s. The strain was visualized and measured using ARGUS software provided by GOM. The results clearly show that the formability of AA6082-T6 sheet metal, in terms of the limit major strain, increased by 38.9 % when the forming temperature was increased from 300°C to 450°C at a speed of 250 mm/s, and increased by 42.4 % when the forming speed was decreased from 400 to 75 mm/s at a temperature of 400°C. It was verified that hot stamping is a promising technology for manufacturing complex-shaped components.
Formability of Explosive Welded Mg/Al Bimetallic Bar
Authors: Mróz Sebastian , Szota Piotr , Bajor Teresa , Stefanik Andrzej
Published: November 2016

The paper presents the results of physical modelling of the plastic deformation of the Mg/Al bimetallic specimens using the Gleeble 3800 simulator. The plastic deformation of Mg/Al bimetal specimens characterized by the diameter to thickness ratio equal to 1 was tested in compression tests. The aim of this work was determination of the range of parameters as temperature and strain rate that mainly influence on the plastic deformation of Mg/Al bars during metal forming processes. The tests were carried out for temperature range from 300 to 400°C for different strain rate values. The stock was round 22.5 mm-diameter with an Al layer share of 28% Mg/Al bars that had been produced using the explosive welding method. Based on the analysis of the obtained testing results it has been found that one of the main process parameters influencing the plastic deformation the bimetal components is the initial stock temperature and strain rate values.
Thickness and Microstructure Analysis on Hot Gas Bulged Cup-Shaped Parts of Ti-22Al-24.5Nb-0.5Mo
Authors: Wu Yong , Liu Gang , Liu Zhi Qiang , Kong Bei Bei
Published: November 2016

Ti2AlNb based alloy has been paid more and more attention in recent years because of their high application potential in jet engines for good mechanical properties at high temperature. However, the control of microstructure and mechanical properties for components in sheet metal forming is very difficult because the complex phase transformation. In this paper, a cylindrical part was produced by hot gas forming and the formability of a Ti-22Al-24.5Nb-0.5Mo sheet with thickness of 2mm was studied at 985°C. It is found that the parts could be formed with small bottom-corner radius of 4mm with outer diameter of 60mm and the depth of 20mm. The strain distribution and thinning ratio of the parts were analyzed. The maximum thinning ratio was 56.3% near to the small corner. The microstructures of the original blank and the cylindrical parts were observed by optical microscopic (OM). It is found that the orthorhombic (O) phase and α2 phase significantly reduced during the forming process. On the other hand, at different position of the parts, different microstructures appear because of different strain values.
Effect of Thermomechanical and Austenite Partitioning Processing on Microstructure and Mechanical Properties of 0.4 Carbon Steel Containing Aluminum
Authors: Farahat Ahmed Ismail Zaky , Mohamed Masoud Ibrahim
Published: November 2016

Casting of steel with different aluminum content was carried out. Thermo-mechanical process was carried out at 1200°C. A cross-sectional area reduction of 95% was done using hot forging hammer. Two regimes of thermomechanical processes were adopted in this study. First regime was intercritical annealing (between AC1 and AC3 to obtain 50% austenite and 50% ferrite) followed by rapid quenching in salt bath to the martensite zone for 15minutes to produce ferrite, martensite and carbon saturated austenite and to prevent the whole transformation of austenite to martensite. The second regime was reheating 50oC above AC3, followed by rapid quenching in salt bath to the martensite zone (for 15 minutes) to get partially partitioned martensite and super saturated retained austenite. The initial tensile strength after hot forging is 1067MPa and 942MPa for alloys 1 and 2 respectively. The tensile strength after intercritical annealing is 1621MPa while after quenching from austenite to martensite zone with austenite partitioning is 2113MPa. Elongation after intercritical annealing and austenite partitioning is null due to bad shapes and distribution of ferrite with sharp corners.
Excellent Formability of Light Metals Sheets by Friction Stir Incremental Forming
Authors: Otsu Masaaki
Published: November 2016

The results about friction stir incremental forming of light metals sheets from the beginning of development to the latest in the author’s laboratory are introduced. Comparison of formability by the conventional single point incremental sheet metal forming and friction stir incremental forming for magnesium alloys, aluminum alloys and titanium sheets were introduced. Effect of tool rotation direction, multistage forming and double side forming are also introduced.
Hot Deformation and Microstructural Characteristics of Nitrogen Enhanced 316L Stainless Steel
Authors: Kumar Santosh , Aashranth B. , Samantaray Dipti , Arvinth Davinci Marimuthu , Borah Utpal , Bhaduri A.K.
Published: November 2016

Dynamic recrystallization (DRX) in 316LN austenitic stainless steel with 0.14wt% nitrogen has been studied using hot isothermal compression tests carried out in temperature range 1073-1423K and strain rate range 0.001 - 10 s-1. Critical strain and stress for DRX has been characterized using experimental data. Analysis of results shows that for the entire domain the critical stress is directly proportional to peak stress. However, no clear relationship between εc and εp prevails over the entire tested domain. Dynamic Recrystallized (DRX) grains are quantified by GOS and KAM maps. The four stages of DRX progression have been identified using the correlation between GOS and critical strain at different deformation conditions.
Investigation of Tensile and Compressive Creep Behaviour of AA2050-T34 during Creep Age Forming Process
Authors: Li Yong , Shi Zhusheng , Yang Yo Lun , Lin Jian Guo
Published: November 2016

The tensile and compressive creep behaviour of aluminium alloy 2050 with T34 initial temper (AA2050-T34) during creep-ageing process has been experimentally investigated and analysed in detail. Both tensile and compressive creep-ageing tests under various stress levels (ranging from 100 MPa to 187.5 MPa) have been carried out at a temperature of 155 °C for 18 hours. The results show that creep strains under tensile stresses are much larger than those under the same levels of compressive stresses and a new “double primary creep feature” with five-stage creep behaviour has been observed in the alloy during the creep-ageing tests. The conventional power-law creep equation was applied to analyse the new creep behaviour of the alloy at the steady-state creep stage. Furthermore, the power-law relationship between the applied stress and the corresponding creep strain rate was found to be effective in all creep-ageing stages of the alloy and was used for further analysis. These analyses indicate that the dislocation and diffusion mechanisms may both contribute to this new creep behaviour and may play different roles in different creep-ageing stages. Moreover, the evolution of the creep resistance or threshold creep stress of the alloy during the creep-ageing process was quantitatively investigated by the proposed relationship. These results help to not only understand the new creep behaviour of AA2050-T34 during the creep-ageing process, but also facilitate further constitutive modelling of this new creep behaviour for its creep age forming applications.
Analysis of Material Flow in Oval Upsetting Using Mild-Wedged Die
Authors: Nomura Takashi , Ngyuen Con , Kitamura Kazuhiko , Matsunaga Keiichi
Published: November 2016

In multiple stages forging, an appropriate pre-form has reduced production cost, loss of material, and forging load, and it has also improved die life. However, it is difficult for beginner to make the process design of the pre-form because they have poor technical information. For example, experts have experimental knowledge how to form an oval cylinder by upsetting of a right cylinder with a mild-wedged die. This oval upsetting needs no container with oval hole. This paper investigates the oval upsetting with the relationship between the nose angle of the mild-wedged die and the shape of the product for assistance of the process design in forging. As the results, when the mild-wedged die having an appropriate angle and nose radius was applied to the upsetting, the oval cross-sectional ratio of the major axis to the minor axis achieved 1.45.
Microstructure and Mechanical Properties of Ti/Cu Clads Manufactured by Explosive Bonding at Different Stand-Off Distances
Authors: Skuza Wojciech , Paul Henryk , Berent Katarzyna , Prazmowski Mariusz , Bobrowski Piotr
Published: November 2016

In this study, unalloyed titanium (Gr.1) and deoxidized high phosphorus copper plates were joined through explosive welding process. Different stand-off distances were used to investigate their influence on the microstructure and mechanical properties of the clad fabricated at the same amount of explosive charge. Microstructures near-the-interface were examined with the use of scanning electron microscope equipped with energy dispersive X-ray spectrometer and then microhardness measurements were carried out on the clad. Microstructure examinations showed that with increasing stand-off distance the length and amplitude of the waviness and the quantity of melted zones in areas near-the-interface increase. The inclusions of the melted zones are formed behind the wave crests on titanium side or within the wave vortex. Microhardness measurements indicate a significant increase of both plates microhardness, especially near-the-interface.
Prevention of Local Thinning and Springback in Hot Stamping of Thin Sheets
Authors: Nakagawa Yuki , Mori Ken-Ichiro , Maeno Tomoyoshi
Published: November 2016

In hot stamping of thin quenchable steel sheet, local thinning, springback and hardness of stamped parts were investigated. The sheets having 0.6, 1.0 and 1.6 mm in thickness were heated at 900 °C by a furnace and hot-stamped into a hat shape. Local thinning around the bottom corner of the hat-shaped part for a thickness of 0.6 mm was considerably remarkable in comparison with those above 1.0 mm in thickness. Local thinning was relieved for a transfer time of 15 s from the furnace because of the uniformity of the temperature distribution. In addition, the springback was prevented above 5s.
Process Effects in Short Cycle Stretch Forming of Tinplate Can Bodies
Authors: Schneider Matthias , Liewald Mathias
Published: November 2016

Short Cycle Stretch Forming (SCS) is an innovative stretch forming technology developed at the Institute for Metal Forming Technology (IFU) at the University of Stuttgart. The SCS technology combines plane pre-stretching of blank and subsequent deep drawing operations within the same stroke of press ram. The sheet metal thickness is reduced while denting resistance and yield stress increases due to hardening effects.Current research work focuses on applying SCS-technology to rotational-symmetrical bodies. A process simulation for SCS-Cupping process was performed for food cans. Based on these results a tool was manufactured and commissioned. The results showed that the thickness of cup bottoms of two-piece drawn and ironed (D&I) steel cans can be reduced. Therefore, it is possible to save material costs in serial production based on a reduced blank diameter.In this paper the different effects leading to the thinning of steel can bottom and failure types, such as, wrinkling and cracking are observed in a number of experimental series. Based on these results, the tool geometry was optimized and an advanced tool was manufactured. The results of this paper show that SCS-Cupping offers promising potential to save material, as well as outlining the main effects for this technology.
Ultrasonic-Assisted Metal Staking with 15 kHz Oscillation Frequency
Authors: Leicht Uwe , Merklein Marion , Engler Sebastian
Published: November 2016

To comply with increasing product requirements, the use of function-optimized materialsis claimed. Joining technology thereby becomes increasingly important to use high strength materialonly in postulated sections. Staking is a joining by forming technology that is highly reliable andcost efficient. High process forces and sufficient formability of the material limit the suitability inclaimed miniaturization for use in industrial applications. A promising approach to break these processlimitations is the use of superposed high frequency oscillation, whereby joining forces could bedecreased. The present study indicates first trials of an ultrasonic (US) assisted staking process of highstrength martensitic steel. Based on high temporal instrumentation, such as laser vibrometer, contactdetection and high-resolution force measurement, the process sequence is characterized and studiedin detail. The researches confirm high potential in force reduction of mean values due to superimposedhigh frequency oscillation with a high dependency on amplitudes. In process, two differentforce-characteristics within three regimes can be identified. Since US assisted forming processes arewell known in literature with harmonic oscillating force signals during process, hammering and soirregular force peaks with changes in contact signal within process, are identified for first time anddemonstrate a highly promising field of application.
Study on Wire Rod Drawing Process Using the Rotating Die
Authors: Tzou Gow Yi , Chen Dyi Cheng , Lin Shih Hsien
Published: November 2016

This study proposes a cold drawing technology of wire rod with rotating die; it carries out an FEM simulation on rotating drawing using DEFORM-3D commercial software. Frictions among the die and the wire material are assumed as constant shear friction. The effective stress, the effective strain, the velocity field, and the drawing force can be determined from the FEM simulation. In this study, effects of various drawing conditions such as the rotating angular velocity, the half die angle, the frictional factor, the die filet on the drawing forming characteristics are explored effectively. From this FEM simulation, it is noted that the rotating die effect can reduce the drawing force and increase the material flow.
Development of a Process Map for Wire Drawing of Pearlitic Steel by Finite Element Analysis Coupled with Damage Evolution
Authors: Lee Yong Shin
Published: November 2016

This work is concerned with the development of a new process map for wire drawing of pearlitic steel considering damage evolution. In this study, a ductile damage is defined as a porosity or void volume fraction and the porosity evolution model proposed by Lee and Dawson is adopted. Dilatational plastic deformation due to growth of micro voids is also considered. Correspondingly, an Eulerian finite element analysis coupled with damage evolution model is utilized in order to reflect the effects of dilatational plasticity due to growth of micro voids. Also, the accumulated damage in wire drawing could be evaluated. Finite element simulation for wire drawing of pearlitic steel are performed for various process conditions such as a half die angle and an area reduction ratio. Especially, the effects of process parameters on the deformation characteristic as well as damage evolution in wire drawing are carefully examined. Finally, a new process map is presented in terms of a half die angle and an area reduction ratio, which can identify the successful process conditions for wire drawing of pearlitic steel. Thus, it would be expected that this process map will help an engineer for the design of wire drawing of pearlitic steel.
Modelling Central Consolidation during Hot Rolling of Cast Products
Authors: Farrugia Didier
Published: November 2016

Extending the range of finished product sizes from a given ingot or concast bloom or billet section is often limited by the minimum area reduction required to ensure effective central consolidation and final mechanical properties. Predicting effective consolidation or level of remnant porosity for a range of steel grade, billet size, pass schedule/roll design and thermo-mechanical conditions has always been an important issue on plant, much more lately in view of recent trends for larger ingots and development of combined forging/rolling strategies. This paper will focus primarily on a fast analytical technique based on roll gap shape and consolidation factors obtained from Finite Element (FEM) Models. New developments based on FEM submodelling are presented briefly. Healing capabilities based on diffusion bonding can be obtained from [1-3].
Parameters Design of Discontinuous Dot Indenter in Fine Blanking Process with Different Thickness Workpiece
Authors: Zhou Fei , Mao Hua Jie , Liu Yan Xiong , Hua Lin
Published: November 2016

This paper proposes a new blankholder to fine blanking process. V-ring indenter has been widely applied in fine blanking to produce clean cut parts, however, it is difficult to be manufactured, the machining accuracy of which is hard to ensure and the cost is very high. In this approach, the fine blanking process combined with discontinuous dot indenter was put forward and the parameters design for workpiece with different thickness was studied with the finite element simulation and the orthogonal experiment methods. The larger burnished surface zone can be obtained by optimizing discontinuous dot indenter parameters. In addition, the relationship between the discontinuous dot indenter parameters and the workpiece thickness was got from data processing. Finally, applying this relationship to fine blank workpiece with different thickness, nearly full clean cut surface part was obtained.
Methodology for Modelling Diffusion Bonding in Powder Forging
Authors: Wang Yi , Mohammed Idris K. , Balint Daniel S.
Published: November 2016

Interfacial bonding has a significant influence on the quality of processed components formed by powder forging. Consequently, modelling the bonding process is important for controlling the condition of the components and predicting optimum forging process parameters (e.g. forming load, temperature, load-holding time, etc.). A numerical model was developed in the present work to simulate diffusion bonding (DB) during the direct powder forging (DF) process. A set of analytical equations was derived and implemented in the finite element (FE) software Abaqus via a user-defined subroutine. The DB model was validated using a two-hemisphere compression simulation. The numerical results demonstrated that the DB model has the ability to: 1) determine the bonding status between powder particles during the forging process, and 2) predict the optimum value for key powder forging process parameters. The DB model was also implemented in a representative volume element (RVE) model which was developed in an earlier work to simulate the powder forging process by considering particle packing and thermo-mechanical effects.
Hybrid Calculations of Bending Deformations for 20 Roll Cold Rolling Mill
Authors: Mauer Paul , Weyh Bernhardt , Mauk Paul Josef
Published: November 2016

In multi-high mills, the slim fixed floating work rolls are supported by primary and secondary intermediate rolls and several supporting rolls mounted pairs-wise on supporting shafts. Over the eccentric adjustment of saddle assemblies and hydraulic adjustment device the roll gap adjusts the specific elastic bending deformation of the support system. Based on a hybrid calculation model the influence and limits of an active adjustment device for 20 roll mill will be presented. Thereby the bending deformations as well as the contact deformations of the complete system including the forming process in settings of the elementary plasticity theory (EPT) will be considered.The modeling of the bending deformations of the roll systems are based on FE-Beam elements. The flattening in the contact zone between the rolls will be formulated by a modified non-linear approach, according to Hertz-Johnson. The contact of the deformed zone is aligned in the discretized EPT-roll model by Alexander with Hitchcock-flattening. The iterative analysis of the compact models leads to “force-deformation-relations”, which provides the influence of the variation of the gap. The force-deformation-relations will be detailed discussed in parameter studies of a real 20 roll mill.
Influence of the Deformation Method on the Microstructure Changes in AZ31 Magnesium Alloy Round Rods Obtained by the Rolling Process
Authors: Stefanik Andrzej , Szota Piotr , Mróz Sebastian , Bajor Teresa , Boczkal Sonia
Published: November 2016

This paper presents the research results of the microstructure changes of the round rods of AZ31 magnesium alloy in the hot rolling processes. The rolling was conducted in duo mill and a three-high skew rolling mill. Numerical modelling of the AZ31 magnesium alloy round rods rolling process was conducted using a computer program Forge 2011®. The verification of the results of numerical modelling was carried out during laboratory tests in a two-high rolling mill D150 and a three-high skew rolling mill RSP 40/14. Distributions of the total effective strain and temperature during AZ31 rods rolling process were determined on the basis of the theoretical analysis. Microstructure and texture changes during both analysed processes were studied.
Fabrication of Deep Cup with Flange by In-Plane Stretch Forming Applying Compressive Force in Thickness Direction
Authors: Kajikawa Shohei , Iizuka Takashi , Kuboki Takashi
Published: November 2016

This paper presents a new stretch forming method that applies compressive force for forming a deep cup with a flange. In this method, a punch and a die having a hole are used, and the main parameters are the depth of the die hole, ddh, and the clearance between the punch and the die, c. The effect of ddh and c was investigated by using an aluminum blank of thickness 2 mm in an experiment and a finite element analysis (FEA). When ddh was too small, the material flow could not be controlled appropriately, and when ddh was too large, a local thinning occurred during initial stretching into the die hole. When c was set at large, the side wall thickness of the formed cup was uneven, but a deep cup could be obtained by setting c below a half of the blank thickness. As a result, a deep cup of height 8.3 mm and with a flange was formed successfully under the condition that ddh was 1.5 mm and c was 0.5 mm.
Friction Stir Welding of Copper Alloy CuETP
Authors: Sibalic Nikola , Vukcevic Milan
Published: November 2016

Experimental researches that were performed in order to determine the mechanical parameters in the process of joining of materials using the FSW process are presented in this paper. The paper presents the joining of CuETP sheet copper alloy, with thickness of 5 mm, and provides details of the friction stir welding process. Besides that, the influence of tool geometry and the regime of welding on the quality of welded joints, was investigated. Experimental studies are made on the basis of the adopted multifactoral orthogonal plan, with varying of factors on two levels and repetition in the central point of the plan. Parameters varied in the experiment were: welding speed, rotation speed of tool, angle of pin slope, pin diameter and shoulder diameter. The family of tools is provided, based on the adopted geometric parameters. The experiment was carried out in a laboratory at ambient temperature in conditions similar to those in the production. In order to determine the quality of welded joints, mechanical tests were performed in the paper, and tensile strength and impact toughness were determined.
Hot Stamping of Titanium Alloy Sheets into U Shape with Concave Bottom and Joggle Using Resistance Heating
Authors: Maeno Tomoyoshi , Yamashita Yuya , Mori Ken-Ichiro
Published: November 2016

The hot stamping of α+β titanium alloy sheet into U shape with concave bottom using resistance heating were performed. Since both edges of the sheet in contact with a pair of electrodes were not heated, cracks occurred around the corners of the bottom due to the partially high flow stress. The cracks were prevented by slitting both edges before resistance heating because of the elongation of the edges. In addition, the hot stamping of titanium alloy sheet into joggle using partial resistance heating were performed. The distortion of sheet was reduced by reduction in area of resistance heating
Effect of Multistage Deformation during the Pipe Processing on Mechanical Properties of Steels Strength Grade X70-X80
Authors: Khadeev Grigorii , Ringinen Dmitrii , Efron Leonid
Published: November 2016

In this research effect of the pipe forming on strength properties of rolled metal was investigated. Deformed state of metal during pipe processing was analyzed and tests with specimens from plate were performed. Analysis of the experimental data was exploited to evaluate effect of the strain on yield stress in each stage of the pipe forming and specimen flattening. The model for estimation of mechanical properties of the rolling mill product based on the required mechanical properties of the pipe was created.
Numerical and Experimental Study on Sheet Hydroforming of 2A12 Aluminum Alloy
Authors: Wang Chu , Wan Min , Yuan Wen Nan
Published: November 2016

In this paper, the sheet hydroforming process of 2A12 aluminum alloy with uniform die cavity pressure on to the blank is proposed and investigated both primarily through the finite element method (FEM) and experiments. The influence of the die cavity pressure curve on the quality of the products was explored and the measures to promote the sheet formability were discussed. The results from the studied case indicate that the profile of the cavity pressure was one of the fundamental parameters directly related to the product's quality and precision. Excessive or insufficient initial pressure is not conducive for the reduction of wall thickness thinning and guarantee of wall thickness uniformity. And the wall thickness thinning is reduced and the thickness evenness is improved by increasing the maximum cavity pressure within a proper range. Moreover, an optimum cavity pressure curve generated by the numerical and experimental methods was properly applied in forming the aluminum alloy part without rupture and with slight wrinkle in the flange area. The study demonstrates that the results of simulations based on the identified parameters were in reasonable agreement with those from experiments.
Temperature Effect on Sorption Capacity of PP Melt Electrospun Ultrafine Fibers in Marine Oil Spill Clean up
Authors: Bubakir Mahmoud M. , He Wan Lin , Li Hao Yi , Ding Yu Mei , Yang Wei Min
Published: November 2016

Marine Oil spills have become a serious environmental problem, and contribute to severe impacts and economic losses. Fast and efficient cleanup of oil from marine environment is vital. The use of sorbents is one of the most efficient techniques in removing oil from water. In this work, pure polypropylene (PP) ultrafine fibers with 2 μm diameter were prepared by air assisted melt electrospinning device to be used as oil sorbent. Two fiber samples were used in this study, fluffy, cotton like appearance and oriented, cloth like appearance with different porosities. The influence of temperature change on oil/water mixture was studied. Fluffy fibers showed a better performance in sorption capacity. Results indicated that change in temperature was an important factor in determining the sorption capacity of the fibers. Additionally, in contrast to solution electrospinning, melt electrospinning is safer, cost effective and environmental friendly because of solvents elimination.
Study on the Acquisition Method of Tire Rubber Parameters Based on Simple Shear Test
Authors: Wang Ruo Yun , He Jian Yun , An Ying , Hu Yong Kang , Fu Xin Hua , Yang Wei Min , Tan Jing
Published: November 2016

Tire simulation gradually becomes an important mean to ensure the quality of the tires. In order to guarantee the reliability of the analysis, the study on the method of obtaining the material parameters is also increasing. According to tire force situation of actual work, the acquisition method of tire rubber parameters based on simple shear test and its application in finite element analysis were studied in this paper. In this research, the international advanced dynamic mechanical analyzer was used to test the tire rubber, and the experimental results were processed by Yeoh hyper-elastic model. The hyper-elastic parameters and thus obtained could be used for finite element analysis of tires, and the simulation results showed that these parameters could be used to simulate the tire performance. In addition, the results could also provide certain guidance for the design and manufacture of tire.
Structure and Electrical Conductivity of Polystyrene/Carbon Black Composites Prepared by Microlayer Coextrusion
Authors: Li Chang Jin , Xiong Liang Zhao , Yuan Cong Ji , Jiao Zhi Wei , Yang Wei Min
Published: November 2016

Electrically conducting composites with a structure of alternating (A-B-A)n layers were prepared by a novel microlayer coextrusion, which were consisted of alternating layers of polystyrene (PS) and layers of carbon black (CB)-filled polystyrene (PSCB). The co-continuous structure with selective location of CB in PSCB layers was controllable by changing the number of multiplying elements, and decreased the percolation threshold and electrical resistivity of multilayered composites because of the double percolation effect. In addition, the multilayered composites exhibited better mechanical properties than that of the conventional blends, which were related to the layered structure and small size of CB aggregates.
Advances in Microcellular Foam Processing of PLA
Authors: Han Zhi Zhong , Zhang You Cheng , Yang Wei Min , Xie Peng Cheng
Published: November 2016

PLA is a bio-based biodegradable plastic, which has excellent biocompatibility and biodegradability. Because the mechanical properties of microcellular foaming material is similar to petroleum-based plastics (PS), PLA foams have been considered as ideal alternative materials. However, PLA has several inherent drawbacks such as low melt strength and slow crystallization kinetics, which severely inhibit the PLA foaming process to produce high-density forms and uniform cell morphology. By adding a chain extender or nanoparticles, and blending with other biological materials, these ways could effectively enhance the expansion ratio and the cell density of PLA and improve the mechanical properties of PLA foams. The most current investigations on microcellular foaming of PLA were reviewed in the article, and outlook of PLA foams was raised.
Crystal Structure and Thermal Property of 1-Ethyl Acetate Pyridinium Ionic Liquid
Authors: Zhao Ya Mei , Su Yan , Cui Hong Meng , Zheng Chang Zheng , Yang Jing
Published: November 2016

[EAPy][PF6] Pyridinium ionic liquid was synthesized by two-step process: introduction of one ethyl acetate group and anions metathesis. Additionally, single crystals of the IL was first obtained by solvent-evaporation method in growth systems. [EAPy][PF6] crystallizes in the monoclinic space group C2/c, with unit cell parameters a =22.748 Å, b =6.204 Å, c =18.552 Å, β =92.66°, z =8,V=2615(3) Å, Dc =1.58 Mg/m3 and F(000)=1264. In its supramolecular structure, the double zigzag chains are formed by hydrogen bonds and these [P(1)F6]- and [P(2)F6]- anions are sandwiched respectively by pyridinium rings and ethyl acetate groups in the packing pattern. Moreover, [EAPy][PF6] exhibits relatively high thermal stability and obvious supercooling during the cooling process, which makes pyridinium IL difficult to crystallize.
Effects of Homogenization Treatment on Dispersoid Characteristics and Recrystallization Behavior in an Al-Zn-Mg-Cu-Zr Alloy
Authors: Xiao Xiang , Liu Cheng , Zhao Jian , Li Wei
Published: November 2016

In the present research, a comprehensive study on the effect of the homogenization treatment on the characteristics of dispersoid and recrystallization behavior in an Al-Zn-Mg-Cu-Zr alloy has been conducted by means of optical micrography, scanning electron micrography and transmission electron micrography. The influence of three process parameters of the homogenization treatment, first stage holding temperature, holding time and heating rate, on the dispersoid characteristics has been throughly studied. The result shows that holding at 400°C for sufficient time is highly beneficial for obtaining fine and uniformly distributed Al3Zr particles. Compared with the high heating rate treatment, the slow one apparently leads to significantly smaller Al3Zr dispersoids, the dimension of the dispersoids decreases from 35 nm to 22 nm, and the number density of Al3Zr particle in the center of the grains increases from 13/μm2 to 35/μm2. The percentage of recrystallized grains of the alloy is found to be affected by dispersoid distribution.
Influence of Wiper Height on 7A55 Slabs
Authors: Wang Li Juan , Zhong Hao , Wang Xiang Jie , Cui Jian Zhong
Published: November 2016

In this paper, weak water cooling technology by wiper is introduced for the casting of 520×1650 mm 7A55 alloy slabs. By analyzing from experiment comprehensively, it indicates that the position of wiper will exert big influence on slab quality. Under the conditions of the experiment, if wiper height is below the bottom of sump, there will be more than 70% possibility for slab to have cracks. If it is excessively higher than 80 mm, the top of the sump, porosity will incur and macro-segregation will be enlarged. The experiment determines the correct height of wiper.
New Progress on Er-Containing Micro-Alloying Aluminum Alloys
Authors: Wu Xiao Lan , Nie Zuo Ren , Wen Sheng Ping , Gao Kun Yuan , Huang Hui
Published: November 2016

Erbium is an effective micro-alloying element in aluminum alloys and has been investigated intensively. Similar with the addition of Sc in aluminum alloys, nanosized L12-ordered Al3Er precipitates were formed coherently with the matrix in Er-containing micro-alloying aluminum alloys. Further, in the case of the addition of both Er and Zr, core-shell-structured Al3(ZrxEr1−x) precipitates, instead of Al3Er, were observed in a fine dispersion. Those thermally-stable precipitates can refine the grain size, minimize the segregation, homogenize the microstructure, enhance the strength, hinder the recrystallization, and thus improve the comprehensive performance of the aluminum alloys. This paper presents the effect of Er on the microstructure, mechanical properties and thermal stability of aluminum alloys. The research of some typical commercial aluminum alloys containing Er, is also reviewed here.
Recent Advances in Research and Industrial Technologies for Aluminum Alloys in Japan
Authors: Sato Tatsuo
Published: November 2016

Recent advances in the fundamental research on the alloy development, microstructure control, property evaluation for aluminum alloys and industrial technologies in Japan is introduced. The production status of aluminum in Japan is also introduced together with the activities in the aluminum organization and academic society. Some of the recent research topics, nanohetero structure and nanocluster controlling, are presented.
Fabrication of Cladding Billet in Diameter of 160mm/148mm by Direct Chill Casting Process
Authors: Cui Jian Zhong , Han Xing
Published: November 2016

The AA4045/AA3003 cladding billet, which has a low clad ratio of 7.5% in size of φ160mm/φ148mm, was prepared successfully by the modified direct chill casting process. Microstructures, elements distribution and mechanical properties of the bonding interface were examined. The results show that metallurgical bonding interface can be obtained with the optimal parameters. The metallurgical bonding interface is free of any discontinuities due to the elements diffusion across the interface. The hardness of the interfacial region is higher than that of the AA3003 but lower than that of AA4045, suggesting that the interface bonding strength is higher than the strength of AA3003. The shearing strength is 82.3 MPa, indicating excellent metallurgical bonding.
The Effect of Heating Rate on the Density and Spatial Distribution of Dispersoids during Homogenisation of 6xxx Aluminium Alloys
Authors: Remøe Magnus S. , Marthinsen Knut , Westermann Ida , Pedersen Ketill , Røyset Jostein , Reiso Oddvin
Published: November 2016

Two 6xxx alloys with different Mn-content have been homogenised in a furnace at 575 oC for 2 hours and 15 minutes. Three different heating rates to the homogenisation holding temperature were chosen, as this was expected to affect the precipitation behaviour of the dispersoids. The study focused on developing a reliable procedure for the characterization of the density and spatial distribution of dispersoids in aluminium alloys; both in terms of sample preparation, microscopic techniques and quantitative analyses of results. Scanning electron microscopy (SEM) has been used to evaluate the dispersoid characteristics for the different alloys and heating rates. The results indicate an increase in dispersoid number density and a more uniform distribution of dispersoids for the lowest heating rate, as compared to the more rapid heating rates, for the alloy with 0.05 wt% Mn. For the alloy with 0.15 wt% Mn the number density increased with the heating rate. This is suggested to be due to particle coarsening as an effect of the low heating rate where the samples spend longer time in the furnace.
Grain Growth Behavior of AlMg5 Alloy Fabricated by Using a New Mg Mother Alloy Containing Al2Ca during Homogenization and Hot Compression
Authors: Kim Bong Hwan , Yoon Young Ok , Kim Shae K.
Published: November 2016

Grain growth behavior of AlMg5 alloy fabricated by using a new Mg mother alloy containing Al2Ca (referred to as AlMg5-Al2Ca hereinafter) was investigated during homogenization and subsequent hot compression test. Normal AlMg5 alloy using a commercial Mg mother alloy showed abnormally grown large grains in its microstructure after homogenization at 520 ̊C for 12hrs, while the grain growth in the AlMg5-Al2Ca alloy was completely suppressed by formation of stable Al4Ca during solidification on grain boundary. The compressive flow stress of normal AlMg5 alloy at 400 ̊C was significantly increased after homogenization because of lack of grains having proper slip directions to the applied load. But the flow stress of AlMg5-Al2Ca alloy showing no grain growth during homogenization was slightly decreased implying lower energy needed for subsequent thermo-mechanical processing.
Study of Hot Deformation Behavior of 6082 Aluminum Alloy
Authors: Wang Peng Long , Jiang Hai Tao , Zhang Rui Jie , Huang Shi Yao
Published: November 2016

A set of hot deformation experiments 6082 aluminum alloy were carried out on the Gleeble-3500 thermal simulation machine. The true stress-strain curves were obtained in the condition of temperatures 425 ̊C,450 ̊C,475 ̊C and 500 ̊C, strain rate 0.01s-1, 0.1s-1, 1s-1 and 10s-1. At the low strain rate (0.01s-1, 0.1s-1), true stress-strain curves exhibited typical work hardening and flow softening features, but at the high strain rate (1s-1, 10s-1), true stress-strain curves just exhibited typical work hardening. The peak stress of current alloy decreased with temperature and increased with strain rate, which can be represented by a hyperbolic sine equation using the Zener-Hollomon parameter (Z). The processing map was calculated and analyzed according to dynamic materials mode (DMM). The processing map showed the reasonable hot working region of 6082 aluminum ally.
Friction-Stir Welding of Zr-Modified AA5083 Sheets in Different Conditions
Authors: Malopheyev Sergey , Mironov Sergey , Kaibyshev Rustam
Published: November 2016

The effect of friction-stir welding (FSW) on microstructure and mechanical properties of Zr-modified AA5083 aluminum alloy was studied. FSW was observed to lead to the formation of fully recrystallized ultrafine-grained microstructures and preservation of nanoscale dispersoids in stir zone. The joint efficiency of the friction-stir welds for ultimate tensile strength was found to be 94% and 74% in the hot-rolled and cold-rolled preprocessed material conditions. The stir zone microstructure was predicted to be stable against abnormal grain growth during post-weld heat treatment.
Effect of Forging Temperature on Deformability and Structure Evolution of High Purity Aluminium during Multi-Directional Forging Process
Authors: Zhu Qing Feng , Wang Jia , Li Lei , Ban Chun Yan , Zhao Zhi Hao , Cui Jian Zhong
Published: November 2016

The effects of final forging temperatures on deformability and structure evolution of high purity aluminum during multi-directional forging process were investigated. The results showed that increasing the initial forging temperature is beneficial for controlling the sample shape in the initial forging passes. Recrystallization during the initial forging passes improves the deformability of the sample in the following low-temperature forging processes. An X-shape fine grain zone is formed in the sample due to the inhomogeneous deformation of multi-directional forging process. When the forging pass is 6, the final forging temperature has an important influence on the grain size in the fine grain zone. The grain size decreases from 302 μm to 60 μm with the final forging temperature decreasing from 310 °C to 65 °C. The X-shape fine grain zone caused by the inhomogeneous deformation cannot be eliminated by increasing the final forging temperature (even higher than the recrystallization temperature of high purity aluminium).
Microstructure and Mechanical Properties of Semi-Solid Die-Cast A356 Aluminum Alloy
Authors: Lei Si Min , Gao Li , Harada Yohei , Kumai Shinji
Published: November 2016

The present work deals with the relationship between microstructure and mechanical properties of A356 aluminum alloy which was produced via thixocasting process under different casting conditions. Feedstock billets were heated to a target temperature to obtain a semi-solid slurry with the required solid fraction. Some billets were heated to a fully-melted condition. In order to obtain fine and spheroidized Al grains, some billets for the partially melting were compressed axially by 33% at a room temperature before heating. The completely-melted and partially-melted slurries were die-cast by using a die-cast machine, and hour glass-shaped rod-type tensile specimens and small-size plate-type tensile specimens were obtained. Small cubic specimens were also collected from the die-cast products for microstructural evaluation. They were polished, and etched by Weck’s reagent. The partially-melted specimen which was compressed before heating shows the spherical Al grains. But the grain of the strain-free partially-melted specimen exhibited complicated morphology. The fully-melted specimen shows the fine and dendrite structure.
Partial Melting, Segregation Behavior and Nanomechanical Properties of AlCu2Si1Mg0.6 Alloy
Authors: Chikova Olga , Ovsyannikov Boris , Reznik Pavel
Published: November 2016

The microstructure, phase composition and nanomechanical properties of AlCu2Si1Mg0.6 alloy was studied where partial melting of grain boundaries during quenching. It was assumed that the following two low-melting eutectics were present along the grain boundaries: α-Al+Cu2Al+Mg2Si and α-Al+Al15(Fe,Mn)3Si2+Si. The measurements of nanohardness and the Young’s modulus in the sub micro volumes were carried out by means of the nanoindentation method using a NanoScan-4D scanning nanohardness tester. An algorithm offered is for calculating the additional pressure that occurs when the mechanical action on the metal having a partial melting of grain boundaries.
Response of Microstructure in High Strength Aluminium Alloy to Graff Sargent Etchant
Authors: Li Cheng Bo , Wang Shao Lin , Liu Sheng Dan , Zhang Xin Ming
Published: November 2016

The response of microstructure in high strength Al-Zn-Mg-Cu aluminum alloy 7055 to Graff Sargent etchant was investigated. It was found that grain boundaries and subgrain boundaries were easily corroded due to presence of η phase, and grain boundaries were corroded more rapidly than subgrain boundaries. The grain structure could be revealed quite clearly after immersion for about 15s. S (Al2CuMg) and Al7Cu2Fe phase were quite stable during immersion if the time was not very long. A dealloying for Al/Mg in the S and Al7Cu2Fe phase was found after long time immersion. Prolonged immersion resulted in serious corrosion of subgrain boundaries, consequently separation of fine subgrains.
Computational Simulation of Localised Corrosion in Anodised AA 2099-T8 Aluminium-Lithium Alloy
Authors: Ma Yan Long , Wu Hai Peng , Wang Zheng Xi , Liao Yi , Huang Wei Jiu
Published: November 2016

The initiation of localised corrosion in anodised AA2099-T8 alloy is simulated by using Cellular Automata (CA) method. For CA simulation, the system consisting of corrosive electrolyte, porous anodic alumina film and alloy matrix is described as a 500×300 two-dimensional square lattice. Eight types of cells are defined to construct the cellular space, with the Von Neumann neighbourhood (four cells neighbourhood) being selected. The cellular space is constructed such that a void generated by oxidation of the high-copper-containing Al-Fe-Mn-Cu-Li particle exists in the porous anodic alumina film consisting of a porous layer and a barrier layer. It is suggested that localised corrosion is preferentially initiated in the void defect region in the porous anodic film, which is related to increased corrosion product diffusion rate in this region compared with diffusion in other regions of the porous layer.