bluuebunny/crossref_metadata_2025 huggingface dataset:
Low and Infra-Low Frequency Measurements in Lead Titanate Solid Solutions
Authors: Bormanis K. , Satarov S.A. , Kalvane A. , Burkhanov A.I. , Shil'nikov A.V. , Dambekalne M.
Published: March 2009

The study of PSN-PT ferroelectric relaxor ceramics exhibiting extreme values of some physical parameters near the morphotropic phase boundary is reported. The results are discussed to account for the relaxor properties related to defects and disordering of the PSN-PT system.
Influence of the External Field on the Polarization in the Surface Layer of Strontium Barium Niobate Crystals
Authors: Malyshkina O.V. , Movchikova A.A. , Ped'ko B.B. , Zaznobin T.O.
Published: March 2009

The influence of an external electrical field and annealing on the polarization state in the
surface layers of strontium-barium niobate (SBN) single crystals is studied. The investigation was
carried out by pyroelectric method and method of thermal Barkhausen effect (TBE). Essential
difference was found to exist in the switching behaviour of pure SBN crystals and SBN doped with
Cr, Ce and Cr/Ce impurities.
Diffusion of Hydrogen in the Ni30Ti50Cu20 Shape Memory Alloy
Authors: Mazzolai Giovanni , Biscarini A. , Coluzzi B. , Mazzolai Fabio M. , Straube U.
Published: March 2009

The chemical diffusion coefficient (Dc) of hydrogen in the Ni30Ti50Cu20 shape memory
alloy has been determined in the temperature range 700 - 1150 K by investigating the kinetics of H2
absorption. The mobility of H has also been deduced between 250 K and 280 K from a Snoek-type
internal friction peak. The values of the Einstein diffusion coefficient (DE) derived from the
relaxation time of this peak were in keeping with those of Dc obtained at low H contents
(nH = H/Me < 0.01 ). The combined Arrhenius plot of DE and Dc gave the following values for the
diffusion parameters: W = 0.52 ± 0.02 eV, D0 = (5±2)x10-4 cm2/s.
Microstructure Changes in Alloy AZ31B in Semisolid State and Its Mechanical Properties
Authors: Ji Ze Sheng , Sugiyama Sumio , Yanagimoto Jun
Published: March 2009

The structural changes of the wrought magnesium alloy AZ31B in semisolid state were
clarified using optical microscopy and hot-stage microscopy. The influence of heat treatment
variables was assessed. Compression tests covering a range from room temperature to 673 K were
carried out for mechanical property assessment; flow stress and breaking strain were determined. The
following are the results: (1) The grain growth of the hot-extruded AZ31B without preprocessing
sensitively reacted at temperature and retention time. (2) The hot-extruded AZ31B with 30 %
preprocessing showed an almost perfectly spheroidized structure in a semisolid state under certain
conditions. (3) Heating velocity markedly affected the spheroidizing rate of grains. (4) From the
direct observation of the hot-extruded alloy AZ31B by hot-stage microscopy, spheroidization was
observed in some crystal populations. (5) Spheroided materials in the semisolid temperature range
had a lower flow stress and a larger breaking strain than nonspheroidized materials. These results
indicate the possibility of manufacturing wrought magnesium alloy by cold working.
Experimental Determination of the Parameters for Modelling Semi-Solid Processing
Authors: Atkinson H.V.
Published: March 2009

The numerical modeling of semi-solid processing requires data on the rheological
properties of materials. This data is often obtained by rheometry but there are difficulties with
characterizing high solid fractions, where the torque which can be exerted with the rheometer is
insufficient. A number of other methods for measuring the flow parameters, including compression
between platens, have been utilized. The various methods will be reviewed in this paper.
Computational fluid dynamics modelers have often used data from steady state experiments but it is
the behaviour during rapid transients which is more relevant to the actual semi-solid processing route.
SiC Nanoparticles Reinforced Magnesium Alloys by Semisolid Process
Authors: Wang Zhao Hui , Kang Yong Lin , Zhao Hong Jin , Xu Yue
Published: March 2009

In this paper, SiC nanoparticles reinforced AM60 alloys were fabricated by semisolid
process with pretreatment of SiC nanoparticles. The microstructure, hardness and mechanical
properties of the alloys have been investigated. The X-ray photoelectron spectroscopy (XPS) was also
used for analyzing elements chemical status of the nanoparticles and the alloys. The microstructure,
hardness and mechanical properties of SiC nanoparticles reinforced magnesium alloys are better than
those of AM60 alloys without SiC nanoparticles addition. The results show that semisolid process
was suitable for fabricating SiC nanoparticles reinforced magnesium alloys.
Investigation of Flow Behaviour and Microstructure on X210CrW12 Steel in Semi-Solid State
Authors: Shimahara H. , Baadjou René , Kopp R. , Hirt Gerhard
Published: March 2009

This paper describes the basic investigation on material behaviour of cold working steel
X210CrW12 in semi-solid state concerning the semi-solid forging. It includes a study of flow
behaviour and microstructure by means of a high temperature isothermal upsetting test applying a
special cylinder sample with a shell, which is designed to avoid collapsing of samples during the
compression. The flow curve of the semi-solid steel is determined by an inverse modelling via FEM
using the obtained load curve of the samples and the separately obtained flow stress of the shell
material. An extensive microstructure study of the compressed samples provides a comprehensive
understanding on the flow mechanism of the semi-solid steel. At the end of the paper some general
restrictions and remarks for the semi-solid forging process are given based on the gained results.
The Effect of Frequency of Electromagnetic Vibration on the Micro Structure in Hypoeutectic Al-Si Alloy
Authors: Choi Jung Pyung , Hur Young Min , Nam Tae Woon , Yoon Eui Pak
Published: March 2009

The structural control of Al-Si alloy, which was not studied among various electromagnetic
processing of materials, was considered applying the alternating current and direct current magnetic
flux density. The main aim of the present study is to investigate the effects of electromagnetic
vibration on the macro and microstructure of Al-Si alloy in order to develop a new process of
structural control in Al-Si alloy. When the electromagnetic vibration is conducted for changing the
shape of primary aluminum, at low frequency (≤ 60Hz), the shape of dendrite is changed speroidal
shape. When the electromagnetic vibration is conducted for changing the shape of eutectic silicon, the
fact that a morphological change of the eutectic silicon from coarse platelet flakes to fine fiber shape
is observed with EMV (Electro Magnetic Vibration) process at high frequency(≥ 500Hz).
Microstructural Evolution and Wear Properties of In Situ Al-4.5Cu-5TiB2 Composite Processed in Mushy State
Authors: Herbert Mervin A. , Maiti Rabin , Mitra R. , Chakraborty M.
Published: March 2009

In-situ Al-4.5Cu-5TiB2 composite plates were stir cast with TiB2 particles formed
through mixed salt route. The as-cast samples with 30 volume percent liquid content were rolled in
mushy state down to 2.5 and 5 percent reduction in thickness per pass. The rolled products found to
be defect-free after the first pass were subjected to multiple roll passes in mushy state with identical
experimental conditions, adding up to seven. The wear properties of as-cast and mushy state rolled
composites were also investigated, and correlated with microstructure.
Design of Experiments for the Optimization the Process Parameters of Thixotropic Aluminum Alloy
Authors: Barcellona A. , Fratini Livan , Palmeri D.
Published: March 2009

The success of the thixoforming process depends on the possibility to confer to material,
when it is found in the semisolid state, a microstructure characterized by globular particles of solid
phase surrounded by a continuous film of liquid phase; such microstructure is obtainable through
particular thermo-mechanical treatments. In the present research, in order to optimize the influence of
process parameters in the step in which the thixotropic properties are conferred to the AA7075
aluminum alloy, the statistic technique of the Design Of Experiments (DOE) has been used. The
advantages in the application of such technique are expressible in terms of reduction the times of
development of process and more efficient use of resources. A Central Composite Design factorial
plan with two levels has been realized to allow the evaluation of experimental error and to check the
adequacy of the model. The experimental tests foreseen from the same plan have been therefore
performed. Using the method of the response surfaces (RSM), the function of response has been
formulated, and the analysis of the experimental data has been realized by the linear regression
method. Finally, the analysis of variance (ANOVA) allowed to value the causes of variability of the
results. Statistic test has been performed on the significance of single factors and their interactions.
Research on Thixoforging Magazine Plate of AZ91D Magnesium Alloy in Semi-Solid State
Authors: Jiang Ju Fu , Luo Shou Jing
Published: March 2009

The thixoforging process in which magazine plates of AZ91D magnesium alloy were
thixoforged in semi-solid state using semi-solid billets prepared by common SIMA method and new
SIMA method was investigated. The results show that the pressure has a great influence on the
semi-solid billet’s ability to fill die’s cavity. When the pressure is 500KN, the semi-solid billet can’t
fill the die’s cavity completely. When the pressure is 2000KN, the semi-solid billet can fill the die’s
cavity completely. Room temperature mechanical properties, such as yield strength of 201.4MPa,
ultimate tensile strength of 321.8MPa and elongation of 15.3%, can be obtained successfully when
the technological parameters, including pressure of 200KN, die preheating temperature of 723K,
holding for 20min at 818K, are satisfied. Comparing with common SIMA, mechanical properties of
room temperature and high temperature at 373Kare enhanced heavily.
Semi-Solid Forming of Al-Mg-Zn Based High Strength Alloys
Authors: Kim Jeong Min , Seong Ki Duk , Jun Joong Hwan , Kim Ki Tae , Jung Woon Jae
Published: March 2009

Semi-Solid Al-5%Mg-3%Zn-1%Mn alloys with or without 0.2%Zr were prepared by the
isothermal heating of either cast ingot or extruded billet. The microstructural and tensile properties
variations during the isothermal heating, depending on alloy composition and slurry preparation
method, were investigated. The grain (globule) size of semi-solid microstructure was not
remarkably changed by the slurry preparation method, however it was significantly reduced by the
Zr additions. The room temperature tensile elongation of the semi-solid formed alloys was generally
higher in case of the extruded billet. T6 heat treatment was not found effective in improving the
strength of the semi-solid alloys, unlike the casting alloys.
Microstructure and Mechanical Properties of Cast and Semi-Solid Formed Mg-Al-Zn Alloys
Authors: Kim Jeong Min , Park Bong Koo , Jun Joong Hwan , Kim Ki Tae , Jung Woon Jae
Published: March 2009

Various Mg-Al-Zn alloys with different Al and Zn contents were fabricated by
conventional casting and semi-solid forming process. And the microstructure and mechanical
properties of the alloys were investigated. In Mg-4%Al-(5~7)%Zn alloys most of the grain
boundary phases were found to be Mg-Al-Zn while in Mg-6%Al or Mg-8%Al based alloys the Mg-
Al-Zn phase coexisted with Mg17Al12 at grain boundaries. At room temperature the semi-solid
formed alloys showed significantly higher tensile properties, especially elongation, than the
conventionally cast alloys.
Evolution of Texture and Strain States in AA 3003 Sheet during Sandwich Rolling
Authors: Huh Moo Young , Kim J.K. , Lee Jael Chul , Suk Han Gil
Published: March 2009

This work focuses on the strain states of the mid AA 3003 strip sandwiched in between
either AA 3003 sheets or STS 430 sheets. For that purpose, the strain states at various
through-thickness layers were analyzed by measurements of crystallographic texture and by
simulations with the finite element method (FEM). During sandwich rolling, the material property of
outer sheets of sandwich samples played an important role in the evolution of the strain states and the
corresponding texture formation. In the mid AA 3003 sheets, rolling with the harder outer sheets gave
rise to pronounced through-thickness texture gradients, whereas fairly uniform strain states prevailed
during rolling with the outer sheets of the same AA 3003.
Dynamic Mechanical Properties of Continuously Cast Al Alloy in Electromagnetic Stirrer
Authors: Lee Dock Young , Kang Suk Won , Kim Ki Bae
Published: March 2009

The mechanical properties of electromagnetically stirred billet of Al alloy during
continuous casting such as a tensile, impact, and fatigue property was examined with respect to a size
and roundness of primary α phase to examine the influence of the globularization and refining of
primary α phase on the dynamic mechanical property. The billet was continuously cast in a casting
speed of 100 to 600 mm/min during the electromagnetic stirring with a magnetic flux density of 700
Gauss and then was heat-treated. All tensile properties were enhanced with decreasing the size of
primary α crystal and the ultimate tensile strength (UTS), yield strength, and elongation was obtained
320MPa, 235MPa, and 17.8%, respectively, at a size of primary α phase of 77 um. The fatigue life at
fracture was largely improved by 37% from 1.25×105 to 1.7×105 cycles and the fracture toughness
was obtained approximately 7.25 joules as a maximum value at a minimum size of primary α phase on
the present experiment condition. Therefore, it indicates that all mechanical properties can be
improved at the higher casting speed owing to the fine microstructure of a primary α phase and also
eutectic phase due to the higher cooling rate.
A Novel Technique to Produce Metal Slurries for Semi-Solid Metal Processing
Authors: Wannasin J. , Martinez R. Andy , Flemings Merton C.
Published: March 2009

Various processing methods exist for applying agitation to a molten metal during
solidification to obtain metal slurries suitable for semi-solid metal processing. . In this paper, a new
technique to achieve semi-solid metal structure using agitation during solidification is reported. The
technique applies a new medium and means to efficiently create semi-solid metal structures. The
results of a systematic study showing the feasibility and the necessary conditions to achieve the
structure are discussed.
Joining Metals by Combining Mechanical Stirring and Thermomechanical Treatment to Form a Globular Weld Structure
Authors: Shalchi Amirkhiz B. , Aashuri Hossein , Kokabi Amir Hossein , Abbasi Gharacheh M. , Mola Javad
Published: March 2009

A method for joining metals in the semisolid state is presented. A model alloy Sn-15%Pb
was used to demonstrate the concept. By presented process, dendritic microstructure of the weld
zone can be avoided. Moreover, near-weld zone of the cold worked substrates which is affected by
heat would have a globular structure due to a thermomechanical treatment. The two substrates were
heated up locally in the joint line to the semisolid temperature range. At this point a stirrer was
introduced into the weld seam in order to mix the two sides into a single uniform joint. Localized
mechanical properties of different zones were examined using Shear Punch Test (SPT), showing a
good strength in the weld zone and thermomechanically affected zone.
Formation of Bulk Metal Ingots with Homogeneous Fine-Grained Structure Using Novel Semisolid Casting Technique
Authors: Tolochko N.K. , Timoshpolski V.I. , Kalinichenko A.S. , Shienok Yu.A.
Published: March 2009

Novel semisolid casting method to produce bulk metal ingots with homogeneous fine-grained
structure is proposed. In the method, the fine-grained particles are subjected to partial melting and
compacting. As a result, the ingot structure is constituted mainly by fine-grained particles bonded
by inerlayers of solidified melt.
Hybrid Preform for Metal Matrix Composites: Processing and Characterization
Authors: Babu J.S.S. , Nair K.P. , Kang C.G.
Published: March 2009

Metal matrix composites (MMCs) have been used for aviation, automobile and nuclear
application due to their highlight properties such as superior strength, high specific stiffness, wear,
and creep resistance at elevated temperature. For developing MMCs by liquid infiltration, preform
will be required. In this research paper, developed a hybrid fiber preform and investigated their
microstructure properties. Graphite nano fiber (GNF) and Alumina fiber were used for fabrication
of the preform. The main objective of developing a preform is i) attainment of uniform distribution
of reinforcement ii) minimization of mechanical and chemical damage. Since, it is extremely
difficult to disperse nano-size fibers uniformly into the preform. An attempt has been made for
hybrid preform with alumina micro-fiber and graphite nano fiber. Microscopic investigations
revealed good disperse of the nanofibers in the preform.
Study on Microstructures and Mechanical Properties of Rheo-Die Casting Semi-Solid A356 Aluminum Alloy
Authors: Kang Yong Lin , Xu Yue , Wang Zhao Hui
Published: March 2009

In this paper, with a newly self-developed rotating barrel rheomoulding machine(RBRM),
microstructures and mechanical properties of rheo-die casting A356 alloy were studied. In order to
clearly show the characteristic of rheo-die casting, liquid die casting and semi-solid casting were done
too. The experimental results showed that microstructures of rheo-die casting were composed of solid
grains, which were finer and rounder, and had fewer pores. In the three technologies, integrated
mechanical properties of semi-solid rheo-die casting were the best.
Semi-Solid Casting of Metal Matrix Nanocomposites
Authors: De Cicco Michael , Turng Lih Sheng , Li Xiao Chun , Perepezko John H.
Published: March 2009

Semi-solid casting (SSC) techniques have proven useful in the mass production of high integrity
castings for the automotive and other industries. Recent research has shown metal matrix
nanocomposite (MMNC) materials to have greatly improved properties in comparison to their base
metals. However, current methods of MMNC production are costly and time consuming. Thus
development of a process that combines the integrity and cost effectiveness of semi-solid casting
with the property improvement of MMNCs would have the potential to greatly improve cast part
quality available to engineers in a wide variety of industries. This paper presents a method of
combining SSC with MMNC in a way that benefits from MMNCs’ tendency to naturally form the
globular microstructure necessary for SSC. This method uses ultrasonically dispersed nanoparticles
as nucleating agents to achieve globular primary grains such that fluidity is maintained even at high
solid fractions. Once particle dispersion is achieved, the material needs no further processing to
become a semi-solid slurry of globular primary grains as it cools. This quiescent method of slurry
production, while still imposing some constraints on cooling rates, has a large process window
making this process capable of industrial rates of throughput. It was found that the key factor to
achieving globular microstructure is a sufficiently slow cooling rate at the onset of solidification
such that particle-induced nucleation can occur. Once nucleation occurs, continued cooling is
virtually unconstrained, with globular microstructure evident in quenched samples as well as
samples cooled at rates as slow as 1 °C/min. This method was demonstrated in several material
systems using zinc (Zn), aluminum (Al), and magnesium (Mg) alloys and nanoparticles of
aluminum oxide (Al2O3), silicon carbide (SiC), and titanium oxide (TiO2). Additionally, several
nucleation models are examined for applicability to nanoscale composites.
Numerical Simulation of Mould Filling in Rheo-Diecasting Process of Semi-Solid Magnesium Alloys
Authors: Wu Shu Sen , Zhao Jun Wen , Wan Li , Luo Jirong
Published: March 2009

The mould-filling behavior of rheo-diecasting of semi-solid magnesium alloy and
diecasting of liquid magnesium alloy has been simulated with the computer program of numerical
simulation developed by the authors. Results show that, under the same diecasting conditions, the
filling behavior of rheo-diecasting of semi-solid metals is similar to the liquid diecasting, but mould
filling of semi-solid slurry is steadier, and the slurry flows into the mould in a state similar to
lamellar flow. The air entrapment in semi-solid process is much smaller than that of liquid
diecasting, and the castings made with semi-solid rheo-diecasting excel those with liquid diecasting
in quality. Experimental results are in accord with the results of numeral simulation.
A New Integration Method Proposed for Hyperbolic Sine Constitutive Equation Used in Semi-Solid Forming
Authors: Zhou Ji Ming , Qi Le Hua , Chen Guo Ding
Published: March 2009

This paper describes a new integration algorithm for hyperbolic sine constitutive equation
(HSCE) used in semi-solid forming. An intermediate variable Lambda ranged from zero to one is
introduced to replace the inelastic strain rate in HSCE so that the inelastic strain rate can be solved
indirectly from the Lambda. The proposed integration algorithm is based on the stress update concept
and the effect of normal stress updating on the material compression is also discussed thoroughly in
this paper. The investigation results show that the new algorithm can integrate the HSCE efficiently
and the normal stress should keep constant as the deviatoric stress updating. An example of
semi-solid extruding was given in the paper at last to illustrate the implementation of new algorithm
and effect of normal stress updating on the compression of material.
Fluid-Structural Interaction Analysis of the MMC-Thixoforging Process
Authors: Liewald Mathias , Unseld Peter , Schneider M.
Published: March 2009

High mechanical properties in combination with low density are key features for
lightweight constructions in automotive and aerospace applications. The combination between the
innovative thixoforging process and the potential of fibre or particle strengthened composites with
metallic matrices (MMCs) provides an efficient manufacturing process of structural components with
continuous or gradient reinforcements.
The scope of the Center of Competence for Casting and Thixoforging Stuttgart (CCT) contains new
semi-solid manufacturing methods for metal matrix composites which have been developed and
applied for patent pending. While previous research projects were focussed on fabrication of
continuous fibre reinforced metal matrix composites, the local reinforcement insertion, located in the
center of high force and torsion load zones, is going to be the next evolution step of the CCT research
team. Therefore it is essential to verify, to simulate and to reproduce the process during infiltration of
the semi-sold matrix metal into the textile layer experimentally.
This paper illustrates investigations regarding the infiltration process of the thixotropic cast-alloys
AlSi7Mg0.3 (A365) into laminated fibre woven fabrics by computational fluid dynamics and
fluid-structure interaction analysis, taking account into specific manufacturing technology, the
rheological behaviour of the alloy with special focus on infiltration behavior.
Thermo-Mechanical Modeling of the Cooling Process during Thixoforging of Fiber Reinforced Light Metal Composites
Authors: Moreno José A. , von Niessen Konstantin , Gadow Rainer
Published: March 2009

Light-metal matrix composites with tailor-made fiber reinforcements offer a good balance between
weight saving and high strength, a key feature for lightweight design in structural applications for
the automotive and aerospace industry. Light-metal MMCs manufactured by thixoforging of
thermally sprayed prepregs additionally exhibit superior mechanical properties of the matrix
material as well as low fiber damage during infiltration of the reinforcement fabric. However, one
of the difficulties during manufacturing of these materials is the difference in the thermal expansion
coefficients (CTE) of matrix and fiber material. Different thermal expansions lead to the
development of residual stresses during the cooling process that can deform the reinforcement
fibers and hence, lead to a decrease of the mechanical properties of the reinforced component.
Modeling by means of finite elements and numerical simulation is used in order to study parameter
variations during the cooling procedure and to select an optimized process route. The modeling and
simulation was performed in a collaborative work between the Institute for Manufacturing
Technologies of Ceramic Components and Composites, University of Stuttgart, and the Polytechnic
University of Cartagena.
Influence of Morphology on the Rheological Behavior of Semi-Solid A356 Aluminum Alloy
Authors: Zhang Heng Hua , Zhang Xian Nian , Shao Guang Jie , Xu Luo Ping , Yang Yi Tao , Sun Bao Liang
Published: March 2009

The morphology of semi-solid alloy is one of the key influence factors on the rheological
behavior of slurry during die filling and the mechanical properties of formed parts. However, it is
difficult to study such effect due to hard controlling of morphology in semi-solid state. In this paper,
a self-developed Searle-type viscometer was used to determine the rheological behavior of A356
aluminum alloy in different morphology, which was refined with the salts mixture of K2TiF6 and
KBF4. The results indicated that the flow behavior of refined A356 alloy in the semi-solid state
possesses obviously thixotropic behavior under isothermal shearing condition with less time to
reach steady state and lower steady apparent viscosity as compared to that of the A356 alloy. During
continuous cooling at a constant shearing rate, the apparent viscosity of refined A356 slurry in the
same solid fraction decreased with the content of Ti. It is shown from quantitative image analysis
that the primary α-Al grain in the refined alloy evolves from dendrites to rosettes or sphericitys, and
then tends to be rounder and finer in higher Ti content. The mechanism of the influence of
morphology on rheological behavior was also discussed in this paper.
Rheology of Semi-Solid Steel Alloys at Temperatures up to 1500°C
Authors: Modigell Michael , Pape Lars , Maier Horst R.
Published: March 2009

The investigation of the flow behavior of semi-solid steel alloys poses a great challenge by
reason of high operation temperatures and the need of ceramic components for the measuring system.
A high-temperature Couette rheometer has been developed to analyze flow properties of semi-solid
alloys up to temperatures of 1500°C. In the present work the alloy under investigation is X210CrW12.
Differently performed experiments clearly show its shear-thinning and time-dependent flow
properties with a yield stress. This flow behavior is modeled using a Herschel-Bulkley approach
where the experimental results achieved serve to identify model parameters.
Semisolid Structure Simulation in Controlled Nucleation Process
Authors: Wang H. , Yao X.D.
Published: March 2009

Computer simulation of semisolid structure formation is of significance in both
understanding the mechanisms of the formation of such structure and optimization the solidification
conditions for the required structure. A modified cellular automaton (mCA) model has been
developed, which is coupled with macroscopic models for heat transfer calculation and microscopic
models for nucleation and grain growth. The mCA model is applied to Al-Si alloys, one of the most
widely used semisolid alloys. It predicts microstructure morphology and grain size during semi-solid
solidification, and determines the effects of poring temperature and mould temperature on the final
microstructure. The simulated results are compared with those obtained experimentally. The resulting
simulations give some insight into the mechanisms about the semisolid structure formation in
Controlled Nucleation process.
Modeling of Semi-Solid A356 Alloy under Upsetting Process
Authors: Shakiba M. , Aashuri Hossein
Published: March 2009

The flow behavior of a semi-solid A356 alloy at high solid fraction was studied. The
mushy zone was considered as an effective two-phase, so that the solid continuum can be
compressible porous media, and the liquid phase interaction with the solid skeleton was of Darcy
type. The semi-solid flow through the upsetting test was modeled in ABAQUS finite element
method software. The Gurson yield criterion has been developed for the modeling process of the
flow behavior of solid porous medium. Specimens were globulized by a thermomechanical process
and then were tested for various percentages of upsetting. The distribution of solid fraction along
the radius of the specimens at different height reduction showed a good correlation with model
prediction.
Filling and Solidification Characteristics during Thixoforming of Copper Rotor for the Electrical Motors
Authors: Lee Sang Yul , Lee Sang Yong
Published: March 2009

Filling and solidification phenomena during thixoforming of copper rotor for small sized
induction motors have been analyzed and characterized by experiment and computer simulation.
Forming defects in slots of thixoformed rotor were examined by microstructural observation. Most
filling and solidification failures were mainly related to complexity in slurry flows through slots in
rotor core. Computer simulation with single slot model showed the effects of die temperature and ram
speed on the filling characteristics clearly. Simulations with flow guide model showed that the control
of filling velocity of slurry at slot and the consideration of possible differences in flow velocity in each
slot are important.
The Use of Small Punch Sample for Testing of Mechanics Properties of Aluminium Alloy Welded Joint
Authors: Qiao Ji Sen , Chen Jian Hong , Zhu Liang
Published: March 2009

This paper uses the small punch test (SPT) to some performance of the materials, have
put forward basic method to test the material tensile mechanics performance from an inverse FE
method with SPT. The research shows that some tensile mechanics performance and stress of each
district of welding seam can be accurate determined by small punch test. This research has offered
the theoretical foundation for characterizing of the welded joint with mechanical heterogeneity
Effect of Electromagnetic Stirring during Solidification on the Morphological Evolution of Primary Solid Phase of Al Alloy
Authors: Lee Dock Young , Kang Suk Won , Kim Ki Bae
Published: March 2009

In this study, in order to develop the cast product of Al alloy having a globular
microstructure by using the elctromagnetic (EM) stirrer, which was specially designed and
manufactured to induce a various fluid flow type of melt during solidification, a morphlogy and size
of primary solid phase of the solidifying slurry was investigated with respect to EM stirring
condition such as an induced magnetic flux density (MFD) and a frequency of input current. The
magnetic flux density of EM stirrer was measured by using a gaussmeter and its distribution and
magnetic force within Al melt was simulated in ANSYS program. The induced MFD was increased
with decreasing a frequency of input current at the same input voltage due to the increased
penetrating depth of magnetic field. But, the magnetic force related directly with a stirring strength
of melt was increased with the frequency. Both a roundness and size of primary α phase of Al alloy
was decreased with increasing a frequency of input current and MFD within the experimental range.
Therefore, the primary α phase was refined and globularized at the higher frequency and MFD.
Application of Semi-Solid Process for Production of the Induction Motor Squirrel Cage
Authors: Youn Jeong Il , Kim Young Jig
Published: March 2009

This paper presents semi-solid processing of Cu-Ag alloy to produce squirrel cage for small
and medium induction motors. Complete die filling could be achieved with the slug at 1065 oC,
casting pressure of 9 MPa and ram speed of 0.08 m/s. There were no defects in squirrel cage and slug
temperature and ram speed affected the slot filling of rotor importantly, however, casting pressure
rarely has an effect of the filling in this experiment. As the same thixoforming condition, when the
ram speed was 1.5 m/s, slurry could not fill the slot and solidified like a needle shape. The rapid flow
like this would be the cause of non-filling defect of slot because the slurry injected and solidified in
the slot firstly was became the obstacle not to flow the rest of the slurry.
Hot Tearing Susceptibility and Fluidity of Semi-Solid Gravity Cast Al-Cu Alloy
Authors: Wannasin J. , Schwam David , Yurko J.A. , Rohloff C. , Woycik G.
Published: March 2009

Aluminum-copper alloys offer both high strength and excellent ductility suitable for a
number of automotive applications to reduce vehicle weight; however, the alloys are difficult to cast
because of their tendency for hot tearing. In this work, semi-solid gravity casting of an
aluminum-copper alloy, B206, was conducted in constrained rod casting molds to study the feasibility
of using the process to reduce or eliminate hot tearing. To demonstrate the feasibility of gravity
casting of the metal slurries, a fluidity test was also conducted. Results show that the hot tearing
susceptibility of the aluminum-copper B206 alloy cast in semi-solid state is lower than those cast in
liquid state with high superheat temperatures. The grain size of the semi-solid cast Al-Cu samples
appears to be finer than those cast in liquid state with high superheat temperatures. In addition, the
metal slurries had sufficient fluidity to fill the molds even with low gravity pressures. The results
suggest that semi-solid gravity casting is a feasible process to help reduce hot tearing.
Structural Evolution and Deformation Behavior of Extruded AZ91 with Ca Addition in the Semi-Solid State
Authors: Liang S.M. , Chen Rongshi , Blandin Jean Jacques , Suéry Michel , Han En-Hou
Published: March 2009

The microstructural evolution and mechanical response in compression in the semi-solid
state of previously extruded AZ91 alloys containing two levels of Ca additions (1mass%Ca (AZC911)
and 2mass%Ca (AZC912)) have been studied. Ca additions have a significant effect on
microstructural evolution and compression behavior of the AZ91 alloy. At 515°C, the liquid fraction
in AZC911 is larger than that in AZC912, so that the compression stress of the AZC912 alloy was
found to be much larger than that of the AZC911 alloy. This behavior is explained through DSC
analysis which suggests that some solid Al2Ca phase remains in AZC912 alloy at this temperature.
Increasing the remelting temperature for this alloy leads to more liquid and coarsening of the solid
particles occurs with increasing holding time.
Application of PVD Coatings for Improvement of Die Performance in Copper Semi-Solid Processing
Authors: Lee Sang Yong , Lee Sang Yul
Published: March 2009

TiAlN/CrN multilayer coatings with an superlattice period of 6.1nm was applied to a
proto-type high temperature segment mold for Cu semi-solid processing so that it was investigated the
possibilities of TiAlN/CrN multilayer coating as a candidate protective coatings to extend the lifetime
of high temperature molds and dies. Much improved performance was obtained from the TiAlN/CrN
coated molds, although different behaviors were observed depending upon the type of substrate mold
materials. . Improvement of mold performance was observed by TiAlN/CrN coating on AISI H13
steel, but TZM alloy with TiAlN/CrN coating was found to be the best candidate as a mold for high
temperature Cu semi-solid processing.
Surface Hardening Treatment in Use of CO Gas and Post-Heat Treatment in C.P. Titanium and Titanium Alloys
Authors: Kim Y.Z. , Murakami T. , Narushima Takayuki , Iguchi Yasutaka , Ouchi Chiaki
Published: March 2009

Surface hardening treatment of titanium materials in use of CO gas was studied including investigation of post heat treatment under vacuum. C.P. titanium, α+β type SP-700 alloy with Ti-4.5%Al-3%V-2%Mo-2%Fe and β type alloy with Ti-15%Mo-5%Zr-3%Al were used. Surface hardening was conducted by heating these materials at 1073K for 21.6ks in Ar-5%CO gas. Subsequently, specimens subjected to surface hardening were heated at 1073k for various time periods under vacuum. While the maximum surface hardness value was the largest in C.P. titanium and the least in SP-700 alloy, hardening layer thickness was the thickest in β type alloy and the thinnest in C.P. titanium. Surface hardening in C.P. titanium was brought about by solid solution hardening due to oxygen and carbon. Enrichment of these elements in the surface layer of both titanium alloys caused continuous variations of the microstructure such as β to α+β, or their volume fractions in the surface hardening layer. Post heat treatment at 1073K increased the maximum surface hardness and hardening layer thickness with an extension of the heating time in C.P. titanium, but the surface maximum hardness decreased continuously in β type titanium alloy. Post heat treatment could remove the thin oxide layer formed by surface hardening treatment.
Development of Solid Nitriding Method Using Thermosetting Waste Plastic
Authors: Sakoshi Kazumasa , Kagaya Chuji , Kagaya Eiji
Published: March 2009

In recent years, global warming and resource exhaustion problems require the manufacturers
to minimize substances of environmental concern and industrial wastes and adopt measures for
expedited recycling. As a result, making effective use of wastes to try for further energy conservation and
high quality products is an important assignment in the heat treatment and surface hardening treatment
fields as well. This study has investigated the effectiveness of waste melamine resin in solid nitriding of
JIS SUS304 austenitic stainless steel plate. After heating the stainless plate in waste melamine resin
fragments and cooling in air, the surface was analyzed. It was found that a nitrided layer had formed on
the surface of the plate, and the nitriding potential of waste melamine was shown to be high. It is
therefore likely that this method can be effectively applied to the development of economically
advantageous high-performance materials and value-added products.
Advanced Surface Hardening Techniques Using Gas Process
Authors: Fujikawa Hisao , Watanabe Takanori
Published: March 2009

Air Water Incorporated Japan (AWI) has succeeded in developing and commercializing new surface treatment technologies. One of them is the NV Nitriding process. Through an activation treatment using fluorine-based gas for the surface treatment of metals before the nitriding treatment, it is possible to remove the oxide film, such as the passive film, formed on stainless steels and Ni-based alloys and also to nitride these alloys on a mass-production scale. The activation effect afforded by fluoride enables nitriding at a temperature about 150°C lower than other conventional processes, achieving minimal thermal deformation and strain. Also, with this activation process, the range of selection of nitriding conditions such as temperature, gas composition and heat pattern has been considerably extended to enable the formation of a nitride layer optimum for the required characteristics of the treated metals. That is, this process can control the thickness of the nitride compound layer. NV Pionite treatment also has been developed as the soluble carbon diffusion process by which to ensure high corrosion resistance and high hardness in austenitic stainless steels using the above activation treatment.
Formation of Tensile Stress Induced Cracks in Flame Hardening Surface Treatment of 12Cr Blade Steel
Authors: Lee Min Ku , Kim G.H. , Kim K.H. , Hong Sung Mo , Kim Wheung Whoe , Hong Soon Jik , Rhee Chang Kyu
Published: March 2009

This paper reports on the formation of tensile stress induced cracks by the application of a flame hardening to 12Cr steels and the monitoring of the flame hardening process at the desirable residual stress state. During the flame hardening of the steels elastic residual tensile stresses were typically generated due to a phase transformation of austenite into martensite and they became greater by increasing both the process temperature and cooling rate. Eventually the cracks were nucleated and propagated across the prior austenite grain boundaries by a generation of large tensile stress, which was accompanied by a drastic decrease in the tensile stress due to a stress relaxation.
Effect of QPQ Salt Bath Oxidation on Corrosion Resistance
Authors: Li Yuan Hui , Luo De Fu , Wu Shao Xu
Published: March 2009

The QPQ complex salt bath treatment is a type of surface technology which contains mainly salt bath nitriding and post-oxidizing processes. The effect of QPQ oxidizing temperature and duration on the corrosion resistance of QPQ treated specimens has been explored by immersion tests and salt spray tests in this paper. All the specimens were post-oxidized after being nitrided at 570! for 2 hours. The material used in this study were 1020 steel. In the immersion tests, the specimens were immersed in 3‰ H2O2 and 10% NaCl water solution. In the salt spray tests, specimens were salt spray tested using 5% NaCl neutral solution. From the experimental data, for high corrosion resistance, conclusions can be drawn:(1) appropriate temperature should be selected carefully in post-oxidizing stage .Too low or too high temperature would decrease the corrosion resistance. (2) The best post-oxidizing duration should generate magnetite film in porous area and should not collapse. (3) In second oxidizing stage, the porous area has been partly eliminated, so the duration should be less than the duration of post-oxidizing.
The Effects of Probe Geometric Shape on the Cooling Rate Curves Obtained from Different Quenchants
Authors: Chen Nai Lu , Zhang Wei Min , Gao Chang Yin , Liao Bo , Pan Jian Sheng
Published: March 2009

In order to investigate the effects of probe geometric shape on cooling curves of
quenchants, the ISO Inconel 600 alloy probe and a flat probe (Dimension: 120 mm × 120 mm ×
20mm, phase-transformation free CrNi-steel) were both adopted to measure the cooling curves of oil,
water and aqueous polymer quenchant. By comparing and analyzing the cooling rate curves
measured by the two kinds of probes, it can be found that the shape of water and oil’s cooling rate
curves obtained using different probes are almost same. While those for the aqueous polymer
quenchant are not, especially at the initial cooling phase. During the initial cooling phase the cooling
rate measured by the flat probe fluctuates in a narrow range, whereas this phenomenon couldn’t be
seen while using the ISO Inconel 600 alloy probe. The reason could be contributed to the geometric
shape difference of the two kinds of probes and the property of inverse solubility of the aqueous
polymer quenchant. In order to illustrate the inverse solubility property of the aqueous polymer
quenchants the probe geometric shape should be considered.
The Design and Application of a Novel Duplex Coating Formed by Laser Pre-Treatment
Authors: Zhang Kun , Wu Chen Wu , Hu Ying , Chen Guang Nan
Published: March 2009

novel duplex coating is presented on steel substrate by laser discrete quenching prior to chromium coating deposition. Due to the periodical changes in the mesostructures and properties of underlying substrate, the cracking and spalling behaviors of the duplex coating are expected to be different from that of conventional coating. A classic erosion experiment is selected to characterize the positive response of the duplex coating subjected to thermal loads. It is found that the surface cracking is partly restrained and the interface cracking is partly arrested. FEM modeling results show that a unique stress state is induced in the duplex coating with the tempering of the discrete pre-quenched regions due to thermal loading, which is believed to be the mechanism of controlling the damage modes.
Heat Treatment Behavior of Tungsten Heavy Alloy
Authors: Baek Woon Hyung , Hong Moon Hee , Kim Eun Pyo , Noh Joon Woong , Lee Seong , Song Heung Sub , Lee Sung Ho
Published: March 2009

This paper focuses on the variations of static and dynamic properties of tungsten heavy alloy with heat treatment. The matrix phase of 93W-4.9Ni-2.1Fe (weight percent) has been penetrated into W/W grain boundaries during a cyclic heat treatment which consists of repeated isothermal holdings at 1150 °C and water quenching between them. By applying the cyclic heat treatment, the impact energy of tungsten heavy alloy is increased about three times from 57 to 170 J. When the tungsten heavy alloy is cyclically heat treated at 1150 °C and then re-sintered at 1485 °C, W/matrix interface is changed from round to undulated shape. The irregularity of the interface is increased with increasing the number of heat treatment cycles. From the measurement of the residual stress of W grains by X-ray diffraction, it is found that the irregularity of the interface is closely related with strain energy stemmed from the difference of thermal expansion coefficient between W particles and matrix phase. From dynamic ballistic test, it is found that the tungsten heavy alloy with undulated W grains forms many narrow fracture bands which are preferential for the self sharpening effect, thus, for the improvement of the penetration performance.
Optimization of Quench Tank Structure Based on CFD Simulation
Authors: Chen Nai Lu , Zhang Wei Min , Li Qiang , Gao Chang Yin , Liao Bo , Pan Jian Sheng
Published: March 2009

In order to investigate the flow rate distribution and improve the flow rate uniformity of
the quenchant in a quench tank, the ultrasonic Doppler velocimeter (UDV) was used to measure the
flow rate of quenchant with agitation, and then a computational fluid dynamics (CFD) simulation was
carried out to simulate the flow rate distribution without / with flow baffles. According to the CFD
simulation results, the structures and positions of flow baffles in the draft-tube were optimized to
obtain the uniform flow rate distribution in the quench zone, which were verified by experiments as
well. The simulation and experimental results show that the UDV is suitable for measuring the flow
rate of a large-size quench tank. This research provided a solid foundation for optimizing the structure
design of flow baffles in production quench tanks.
Evaluation of Microstructure and Mechanical Properties of Metals by Non-Destructive Methods
Authors: Kwun S.I. , Byeon Jai Won
Published: March 2009

Microstructural parameters (kinds of phases, inter-lamellar spacing of pearlite, precipitate size, number of precipitates), mechanical properties(UTS, Vickers hardness) and non-destructive parameters(ultrasonic velocity, ultrasonic attenuation coefficient, electrical resistivity, magnetic coercivity, magnetic remanence, Barkhausen noise) in various metallic materials were measured in order to investigate the mutual relationship among these parameters. The optimum non-destructive parameters were selected for particular purposes in order to evaluate the level of damage to the metallic structures, to differentiate the microstructures and to predict the mechanical properties of superalloy, low and eutectoid steel and Cu alloys non-destructively.
Influence of Plastic Deformation during ECAP on Precipitation Temperature of γ″ in IN 718 Alloy
Authors: Kim Il Ho , Kwun S.I.
Published: March 2009

The formation behavior of γ″(Ni3Nb) precipitates in IN 718 alloy before and after ECAP(equal channel angular pressing) was investigated by microstructural observation and the hardness test. For the alloy examined before ECAP, the γ″ precipitates were formed only after aging treatment at 720, whereas after ECAP, the γ″ precipitates were formed at the aging temperatures of both 600 and 720. 600 is normally too low a temperature for γ″ precipitates to be formed in commercial IN 718 alloy, however, they were able to be formed due to severe plastic deformation by ECAP. It was found that the ECAP process changed the formation behavior of the γ″ precipitates in IN 718 alloy.