bluuebunny/crossref_metadata_2025 huggingface dataset:
Microstructural Study of Primary Solid Particles in High Density Semi-Solid Al-Zn-Mg Alloy during Stirring
Authors: Lee Joo Ho , Kim Young Ho , Lee Jung Il , Kim Il Ho , Ur Soon Chul , Lee Ho In
Published: March 2009

The formation and character of grain boundaries in the primary solid particles observed in
the metal slurries of stircast Al-4wt%Zn-1wt%Mg alloy were studied. In the semi-solid state of the
solid fraction (fs) of more than 0.5, fracturing of solid particles appears to be dominated by shear force
at high temperature, whilst in fs < 0.4 dendritic fragmentations are expected to occur by grain
boundary melting. In case of shear rupture at fs > 0.5 coarsening of spherical solid particles takes place
by Gibbs-Thompson effect of small particles remelting leading to solute redistribution.
The Effect of Frequency of Electromagnetic Vibration on the Primary Silicon Size in Hypereutectic Al-Si Alloy
Authors: Yoon Eui Pak , Choi Jung Pyung , Yoon W.Y. , Kim Myung Ho , Kim K.H , Nam Tae Woon
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 control of the size of primary Si phase in order to develop a new process of structural
control in Al-Si alloy. If the current density conducted for making high frequency electromagnetic
vibration (EMV) (≥ 500Hz), the size of primary Si phase goes to small. If it conducted for making low
frequency EMV (≤ 200Hz), the size of primary Si phase goes to large. This phenomenon considered
to be related the collision, agglomeration and diffusion of silicon atoms.
Development of Abnormal Grain Growth in Cold Rolled and Recrystallized AA 5182 Sheet
Authors: Suk Han Gil , Shin E.J. , Huh Moo Young
Published: March 2009

Grain growth in the cold rolled and subsequently recrystallized AA 5182 sheets was
investigated by means of microstructure observations and texture measurements. Grain growth
behavior strongly depends on the annealing temperatures. Grain growth hardly took place at
temperatures lower than 470°C, which is attributed to a low mobility of grain boundaries. Abnormal
grain growth occurred at temperatures ranging from 480 to 530°C. Annealing above 560°C gave rise
to the dissolution of inhibitor precipitates, which led to normal grain growth.
Effect of Partial Remelting Procedure on the Microstructural Evolution of 7075 Al Wrought Alloy for Thixoextrusion
Authors: Jo Hyung Ho , Yoon Young Ok , Lee Jin Kyu , Kim Shae K.
Published: March 2009

The feasibility study for thixoextrusion of 7075 Al wrought alloys was carried out with
respect to reheating profile, isothermal holding temperature and time during the partial remelting
through simple partial remelting. The reheating rates were 40/min and 60/min. The isothermal
holding temperatures were controlled at 609, 622, 628 and 632 for 0, 2, 5, 10 and 30 min.
The interesting point of this study was that the thixotropic structures of 7075 Al wrought alloy
without additional pretreatment could be obtained through simple partial remelting. The average grain
size was significantly smaller in the quickly heated specimen. The liquid fraction was increased with
increasing isothermal holding temperature and time while the average grain size was inversely
proportional to isothermal holding temperature and time. However, there was no big change of liquid
fraction and average grain size with respect to isothermal holding time. The important fact that the
liquid fraction and average grain size were almost uniform after 5 min is considered very useful for
thixoextrusion in terms of actual extrusion time.
Effect of Vertical Electromagnetic Stirring on the Grain Refinement of A356 Aluminum Alloy Inoculated by Al-5Ti-B
Authors: Yang Zhao , Bae J.W. , Kang C.G.
Published: March 2009

In this paper, the influence of electromagnetic stirring on the grain size of A356 alloy
inoculated by Al-5Ti-B was investigated. It is found that when stirring is applied at the same time
with Al-5Ti-B, the inoculation effect will be disabled. X-ray determination and SEM observation
show that stirring hinders the deposition of TiB2 particles; consequently hinder the formation of
TiAl3 particles, which were proved to be the nucleus of primary α aluminum phase.
If the stirring time is short, the grain size will be abnormally coarse. This experiment also confirms
that the grain refinement of rheocasting is caused by dendrite fracture instead of modified
nucleation.
Microstructure and Aging Behavior of AZ91 Mg Alloy Fabricated by Inclined Cooling Plate
Authors: Shim Sung Yong , Lim Su Gun
Published: March 2009

Semi-solid AZ91 magnesium alloys were produced using a cooling plate followed by
quenching in the mold. The cast and T6 heat treated microstructures were microscopically
characterized and subjected to hardness tests. It was found that the resultant microstructure in water
quenched semi-solid specimen were finer than that in conventional permanent mold cast specimen.
The hardness tests also showed that the hardness of quenched semi-solid cast specimen was higher
than that of permanent mold cast specimen. This was attributed to large amount of precipitates
which results from fine precipitation of eutectic phase at intergranular areas during the aging
treatment after its complete dissolution.
Effect of Ultrasonic Vibration on the Dispersion of Carbon Nano-Fibre Reinforcement through Semi-Solid AZ91D Magnesium Alloy
Authors: Mussi R.G.S. , Motegi Tetsuichi , Tanabe Fumi , Kawamura H. , Anzai K. , Shiba D. , Suganuma M.
Published: March 2009

Ultrasonic vibration was applied to the surface of AZ91D/CNF slurries in order to
homogeneously disperse the reinforcement through the semi-solid matrix, and eliminate the clusters
of nano-fibres originated during previous processes. The method utilized to produce the slurry was a
modified compocasting process that generates semi-solid magnesium alloy using an inclined cooling
plate and mechanical stirring. The CNF reinforcement was added in quantities varying from 1 to
3vol% and different vibration times and amplitudes were applied to the slurries under isothermal
conditions. Macro and microstructure combined analysis showed the occurrence of grain refinement
in the whole ingot for higher wave amplitudes at shorter times, while for lower amplitudes longer
times up to 10min. were required. Vibration times over 10min were not significant to further improve
the results and times up to 4min did not seem to provide any result whatsoever. The best results,
however, were obtained for 16 and 18μm amplitudes. Discontinuous application of ultrasound seems
to produce better results than continuous vibration. The dispersion of reinforcement seems to occur
by the smash of CNF clusters due to the movement of the solid fraction present in the Mg alloy slurry,
and by cavitation, responsible also for some microporosity present in the microstructures.
Development of an Advanced Rheocasting Process and Its Applications
Authors: Hong Chun Pyo , Kim J.M.
Published: March 2009

Among semisolid forming processes, increasing attention has now been focused on the
commercialization of casting processes based on rheocasting in aluminum automotive casting fields
because of its advantages compared to thixoforming, in regards to the efficiency in cost and
productivity, and mechanical properties.
In this paper, an advanced rheocasting process is introduced, which has been developed recently at
Yonsei University and is now on the way to practical uses in Korea and Japan. In this method, the
semisolid slurry production is based on the nucleation method, in which the nuclei of primary
phase formed in the melt are prevented to grow into dendrites, instead they grow into fine globular
particles to become semisolid slurry having rheological behavior. By increasing the number of nuclei,
very fine and uniform globular microstructures can be obtained, resulting in an increase of mechanical
properties. Recently, commercial rheo-diecasting machines based on the present method have been
developed, and now are being used in manufacturing aluminum automotive casting parts.
Furthermore, the present method is now being tested to investigate its possibility of application to
various alloy systems.
The Effect of Initial Microstructure of A356 Alloys on the Mechanical Behavior in the Semisolid State
Authors: Ning Zhi Liang , Wang H. , Sun Jian Fei
Published: March 2009

The quality of semisolid casting largely depends on the formability of the semisolid
feedstock. Despite of the semisolid casting process conditions, the initial microstructure of the
feedstock plays a significant role in determining the metal formability under the semisolid state. In
this study, the effect of initial microstructure of A356 alloy on the mechanical forming response in its
semisolid state was investigated. A wide range of the initial microstructures varied from a very coarse
dendritic structure to a fine globular structure were produced in A356 alloy using the Controlled
Nucleation Method, particularly by controlling pouring temperature during solidification. Cylindrical
specimens with 12 mm in diameter and 10 mm in height were compressed to a height reduction of 8
mm at constant strain rates from 1.3910-1 /s to 1.3910-3 /s. Strain rate jump tests were also carried
out in order to evaluate the strain rate sensitivity at high fraction solid of 0.9. The materials produced
with a low superheat exhibit a fine globular structure. They showed a very low compression stress in
the semisolid state compared with the materials poured at high temperatures, which have coarse and
dendritic structure.
Fluid Flow Investigation of Die Cast Tensile Test Bars
Authors: Forté Martin , Bouchard Dominique , Charette André
Published: March 2009

The fluid flow of an A356 semi-solid aluminum alloy filling a die consisting of four
tensile test bars was investigated. Numerical simulations were carried out by implementing a
mathematical model in a finite element software. Additional simulations were also obtained with a
physical model in which tomato paste was used as the analogue fluid for the semi-solid aluminum.
The modeling results were complemented by a series of experiments where tensile test bars were
produced from semi-solid aluminum with a high pressure die casting press. The correspondence
observed with the two modeling approaches and the casting experiments is discussed along with the
effect the die geometry had on the flow patterns.
Evolution of Primary Particles Morphology during Secondary Cooling in SSR® Process.
Authors: Reisi Mehdi , NIROUMAND BEHZAD
Published: March 2009

In this study effects of secondary cooling rate upon morphology and size of primary
particles in Al-7.1wt% Si slurry produced by SSR process were examined. SSR slurries with
various solid fractions were poured into a wedge-shaped steel die to produce a range of secondary
cooling rates. The extent of primary particle growth during secondary cooling at various cooling
rates was estimated at 0.05, 0.1, 0.2, 0.3 solid fractions using a 1/3-power law relationship. The
results indicate that for a given cooling rate primary particles in higher solid fraction SSR slurries
grow less significantly during quench than those in low solid fraction slurries. The shape factor of
primary particles also depends on secondary cooling rate and solid fraction and decreases with
increasing the secondary cooling rate and/or the solid fraction.
Application of CSIR Rheocasting Technology for the Production of an Automotive Component
Authors: Govender Gonasagren , Ivanchev L. , Jahajeeah N. , Bëan R
Published: March 2009

The Council for Science and Industrial Research has developed and patented a rheocasting
process. The process involves the preparation of semi-solid slurries from liquid metal, by controlled
cooling and MHD stirring using induction coils. An industrial prototype was designed and built to
test the system in an industrial environment.
A semi-solid high pressure die casting cell was set up with an industrial partner and the system was
tested under normal production conditions. The production cell consisted of the CSIR rheocasting
system, a six axis robot, dosing furnace and 400 ton H-400SC shot controlled Bühler HPDC machine.
An engine mounting bracket originally designed for liquid HPDC was redesigned for SSM forming
(casting) taking into consideration the flow and thermal behaviour of semi-solid casting process, the
function of the component and the required mechanical properties. Although a full production run
was not completed due to an ancillary equipment failure, sufficient castings were produced to perform
preliminary evaluation of the components. The processing parameters used were, die temperature of
250°C, SSM casting temperature of 580°C ±1Cº and a piston injection velocity of 0.13 m/s. Initial
evaluation showed evidence of casting defects due to a combination of factors: die
design/manufacture, casting parameters and poor foundry practice. From the mechanical tests it was
evident that if the die design, casting parameters and foundry practice are optimized components with
adequate mechanical properties can be reliably produced.
Development of In-Ladle Direct Thermal Control (DTC) Rheocasting Process
Authors: Lee Jin Kyu , Yoon Young Ok , Jo Hyung Ho , Kim Young Jig , Kim Shae K.
Published: March 2009

In recent year, various rheocasting methods, other than stirring in the semisolid state, have
been developed to produce a fine globular primary phase in cast alloys. These new methods, called as
slurry-on-demand, involve the controlled nucleation and growth/ripening of primary phase during
partial solidification. In-Ladle direct thermal control (DTC) rheocasting has been competitively and
successfully developed. It requires no processing equipment outside of the casting machine, no grain
refinement procedure and no additional cycling time except for cooling down to the desired casting
temperature. Process concept of In-Ladle DTC rheocasting is simply based on the fact that there is
slurry and mush transition in the range of liquid fraction of 0.1 to 0.6 and the fact that the transition
could be controlled by controlling the shape of solid and the relative energy. This study is mainly
concerned about the feasibility to achieve semisolid slurry during partial solidification only through
thermal and time control, this is, by In-Ladle DTC rheocasting. Based on the optimum conditions
obtained by thermal modeling, microstructural evolution of Al alloys was carried out by In-Ladle
DTC rheocasting. The fluidity was also investigated by In-Ladle DTC rheocasting for Al alloys.
Mechanical Behavior of Processed AZ91D by Equal Channel Angular Extrusion during Semi-Solid Isothermal Compression
Authors: Jiang Ju Fu , Luo Shou Jing
Published: March 2009

Mechanical behavior of processed AZ91D magnesium alloy by equal channel angular
extrusion during semi-solid isothermal compression was investigated using semi-solid isothermal
compression test. The results show that there are four stages, drastic increase of true stress, drastic
falling of true stress, steady stage and increase of true stress. With the increase of holding time or
deformation temperature, required true stress for obtaining same true strain falls evidently and peak
stress and steady stress also fall in true stress-strain curve. With increasing strain rate, steady stress
also increase. Peak stress will increase or decrease with the sudden increase or fall of strain rate.
During semi-solid isothermal compression, plastic deformation of semi-solid billet mainly depends
on plastic deformation of solid phases and their rotation and sliding. Coarse grains occur in upper
position adjacent to compression die’s surface and fine grains occur in the central and free surface
positions of billets.
Microstructural Evolution of A206 Al Alloy by In-Ladle DTC Rheocasting
Authors: Lee Jin Kyu , Kim Shae K.
Published: March 2009

This study is mainly concerned about the possibility to achieve semisolid slurry during
partial solidification only through thermal and time control, that is, by In-Ladle direct thermal control
(DTC) rheocasting for A206 Al alloy. This is based on the fact that there is slurry and mush transition
in molten metal, which is controlled by the shape of solid and the relative energy. Thermal modeling
of heat behavior with respect to ladle material and ladle design was investigated by 2-dimensional
finite volume method (FVM). Based on the optimum conditions obtained by thermal modeling,
microstructural evolution of A206 Al alloy by In-Ladle DTC rheocasting was carried out. Also,
fluidity was investigated by actual In-Ladle DTC rheocasting for optimizing conditions of A206 Al
alloy.
Aging Behavior of Al-Cu Alloys Produced by Melt Extrusion Process
Authors: Lee Byoung Soo , Joo Dae Heon , Cho Hoon , Jo Hyung Ho , Kim Myung Ho
Published: March 2009

Melt extrusion is a new fabrication process with the characteristics of both casting and
extrusion. In this process, a metallic melt which is poured and solidified up to semisolid state in the
container can be directly extruded through the die exit to form a product of bar shape without other
intermediate processes. The aging behavior of Al-Cu alloys in the semisolid state was investigated.
And the microstructure and mechanical properties of the melt extruded Al-Cu alloy bar were
measured and its characteristics are compared with those of a hot extruded Al-Cu alloy bar. Al-Cu
alloys were successfully extruded after squeezing out of liquid during melt extrusion with smaller
force compared to the solid extrusion. Al-Cu alloys bar with the mean grain size of up to 200 μm was
fabricated by melt extrusion process. And the mechanical properties of the melt extruded Al-Cu alloy
bar were improved after the T6 treatment.
Application of Computer Simulation in Developing Automotive Parts of Al Alloy by Using Semi-Solid Die Cast Process
Authors: Yang Yi Tao , Zhang Heng Hua , Shao Guang Jie
Published: March 2009

To aid the optimizing design of filling system, computer simulation technique is introduced
to predict injection-forming process and to protect defects during trial manufacture of automotive
parts by using semi-solid die cast process. By comparing formed appearance of parts in experiments
and that in simulations, and observing the relationship between internal defects inspected by X-ray
and flow field obtained in simulation, it is indicated that there are quite good agreements between
simulation and experiment, right predictions for cast defects resulting from filling process can be
made and improving direction is proposed. The realization of numerical visualization for filling
process of high speed during semi-solid die cast process will play an important role in optimizing
technology plan and process.
Thixotropic Behavior of Semi-Solid Magnesium Alloy
Authors: Chen Hsueh I , Chen Jyh Chen
Published: March 2009

By a high-temperature Couette type viscometer, we studied the thixotropic behavior of
the semi-solid AZ91D magnesium alloy slurry. According to different variable conditions, we could
measure the change of the shear stress. The results showed that the shear stress of semi-solid
AZ91D magnesium alloy slurry increased at starting shearing, and the shear stress fell down at the
maintained shear rate shearing. In our experiment data, we found that the semi-solid AZ91D
magnesium alloy slurry had the behavior of shear thinning fluid. As the maximum shear rate
increased, the measured shear stress increased at a dissimilar level. When the rising time was
shorter, the increasing range of shear stress was larger. As the shearing time of the maintained
shear rate increased, the falling down degree of the shear stress increased and it can be presented as
a function of shearing time, such as: e 0.0159t
min 11331 τ = − . At the same shear rate, the area of
hysteresis loop was bigger and the thixotropic behavior was more obvious.
Series Production of Thixoformed Steel Parts
Authors: Behrens Bernd-Arno , Fischer Dirk , Haller Bjoern , Rassili Ahmed , Pierret Jean Christophe , Klemm Hagen , Studinski Andreas , Walkin Bengt , Karlsson Mikael , Robelet Marc , Natale Luigi , Alpini Flavio
Published: March 2009

In recent years several attempts were made to transfer the thixoforming technology of steel parts
into industrial applicable processes. This paper gives an overview about the progress of a European
consortium that established a fully automated thixoforming process for the series production of
automotive steel parts. Due to the multi-faceted nature of this technology, problems concerning the
development of suitable steel grades and tool materials as well as the development and application
of an inductive heating system, a handling unit and of a complex forming tool had to be solved.
Besides the development of adapted steel grades and the inductive heating, the handling of the semi
solid billets plays a special role because during the manipulation of the parts from the heating station
into the tool a loss of heat is unavoidable. Furthermore, scaling of the parts must be prevented.
By means of a fully automated process line existing constraints were reduced and the forming process
is kept reproducible.
Improved silicon nitride composites have been developed as a tool material, which show good mechanical
properties in combination with an acceptable chemical stability at the occurring process
temperatures as well as in contact with semi solid steel.
Basing on the practical experience a comparison of the thixoforming technology to existing processes
and an outlook for the future are given.
Steels with Different Carbon Content for High Pressure Die Casting in Semisolid State
Authors: Küthe Fabian , Afrath C. , Bührig-Polaczek Andreas
Published: March 2009

Some excellent projects have been finished successfully since the last conference on the pre-industrial
stage showing the great potential of thixoforming technology for steels [1][2]. Experiments presented
in this paper on induction heating, process window and mould filling of three widely-used steel alloys
offer an even greater field of application for industrial companies.
In the past thin walled cutting tools and complex impellers made of cold working steel X210CrW12
were produced at the Foundry Institute [3][4]. Constitutive on this knowledge the field of applications
is enlarged by research on two further steel alloys. Processing of 100Cr6 (roller bearing steel) and
42Cr4 (annealing steel) is challenging due to a decreasing window at a higher temperature level with
decreasing carbon content.
An exact procedure has been worked out to create new control programs for the induction heating
unit. It is based on thermo-chemical calculations and delivers billets with feasible temperature
distribution and well defined content of liquid phase.
Material characterization is performed in a step-die (seven steps between 25 and 0.5mm), especially
developed for demands of semi-solid casting. Mould filling capacity, micro structural evolution and
mechanical properties are determined on each of the seven steps.
For any reproducible process the knowledge of suitable system parameters is essential. To find the
limits of the process window sensitive experimental parameters were changed systematically for each
of the three steel alloys. In addition to tool temperature the process windows consist principally of
content of liquid phase fs, piston velocity vP and pressure during freezing pfr. Characteristic
differences appeared between the different steel grades.
The thermal simulation was used to find functional dimensions for the gating system and to shorten
process times. Simulation of tools system was used to estimate the additional thermal load induced by
higher working temperatures. The abrasive wear at the offsets to the next steps was in the same order
of magnitude for all examined steels.
These results provide the opportunity for commercial steel grades to cast complex steel parts in high
pressure die casting.
Simple Manufacturing Method for A7075 Aluminum Alloy Slurry with Fine Granules and Application to Rheo-Extrusion
Authors: Uetani Yasuhiro , Nagata Ryotaro , Takagi Hidetoshi , Matsuda Kenji , Ikeno Susumu
Published: March 2009

Semi-solid slurry of A7075 aluminum alloy with fine solid granules was tried simply to
make by passing the melt through upright tube followed by inclined water-cooled tube. Structures
of solidified slurries were granular and mean grain sizes of about 0.06 to 0.11mm could be obtained.
When the slurries introduced into an extrusion container kept at semi-solid temperature 873K were
extruded to round bars at various extrusion ratios and press ram speed of 10mm/s, just after cooling
to 833K, they could easily be extruded to bars with smooth surfaces at lower forces. Although every
tensile strength of extruded bars were lower than that of hot-extruded one, there was a tendency that
finer the solid granules in slurry, higher the tensile strength of extruded bar.
Continuous Strip Casting, Microstructure and Performance of Ag-Cu Brazing Alloy
Authors: Lee Kee Ahn , Kim Sung Jun , Kim Young Mo , Kim Moon Chul
Published: March 2009

This study sought to examine the suitability of the continuous strip casting process as a
new fabrication method for the Ag-Cu brazing alloy. Several continuous strip casting processes
such as planar flow casting, melt dragging, and twin roll strip casting were applied to the
manufacture of the Ag-32%Cu strip. In particular, twin roll strip casting was found to realize the
best strip shaping ability and microstructural homogeneity. The effect of aging heat treatment on the
microstructure and mechanical properties of a Ag-Cu strip was also investigated through tensile test,
hardness test, X-ray diffraction (XRD), scanning electron microscopic (SEM) observations, and
electron probe microanalysis (EPMA). Tensile results showed gradually decreasing strengths and
simultaneously increasing elongation with longer aging time. An appropriate TS strength of 283
MPa and a significantly enhanced plasticity of 41% were realized with aging condition of
670oC/2hrs. Finally, twin-rolled strips 1 mm thick could be cold-rolled to a very thin strip (80~100
μm thickness). The microstructural evolution and crystalline morphologies of Ag-Cu metastable
strips were also investigated and related to the mechanical properties.
Thixoforging of 7075 Aluminium Alloys at High Solid Fraction
Authors: Vaneetveld G. , Rassili Ahmed , Lecomte-Beckers Jacqueline , Atkinson H.V.
Published: March 2009

Thixoforging is a type of semi-solid metal processing at high solid fraction (0.5<fs<1), which involves
the processing of alloys in the semi-solid state. 7075 alloy has been used as a feedstock for
thixoforming in order to investigate thixoformability of a high performance aluminium alloy at high
solid fraction. The microstructure in semi-solid state consists of fine spheroidal solid grains
surrounded by liquid. Thixo behaviour allows laminar flow that avoids macro-porosity and other
casting defects and gives better mechanical properties; so we can reduce the weight of functional
parts. Higher solid fraction of 7075 alloy is less sensitive to temperature, avoids metal splash at high
speed, allows laminar flow at high speed and gives a good smooth surface without stick-slip
phenomenon. The process is quicker with less energy and so the production rate increases and the tool
has longer life. However, high solid fraction promotes freezing flow because of faster solidification
and the lack of liquid phase. This freezing flow creates solid/liquid segregation and increases the
forming force.
Anodic Oxide Layer Formation on A357 Aluminium Alloy Produced by Thixocasting
Authors: Forn Antonio , Picas Josep A. , Baile Maite T. , Menargues Sergi , García V.G.
Published: March 2009

Anodizing is widely used in the surface treatment of aluminium alloys in order to preserve
the integrity of the alloy surface, to minimize the need for maintenance and repair, and to maximize
the component life. The aim of this work is to study the influence heat treatments (T5 and T6) have on
the anodization of A357 aluminium alloy produced by a Thixocasting process. In particular the effect
of shape, size and distribution of silicon and intermetallic phases on the anodic oxide film formation.
SEM and EDS analyses were used to examine the microstructural features found on, within and under
the anodic oxide layer. Experiments using a tribometer (pin-on-disc tests) were performed in order to
evaluate the friction and wear properties of the different layers.
Low Temperature Fluidized Bed Nitriding of Austenitic Stainless Steel
Authors: Haruman E. , Sun Y. , Malik H. , Sutjipto Agus Geter E. , Mridha S. , Widi K.
Published: March 2009

In the present investigation, low temperature nitriding has been attempted on AISI 316L austenitic stainless steel by using a laboratory fluidized bed furnace. The nitriding was performed in temperature range between 400°C and 500°C. X-ray diffraction, metallography, and corrosion tests were used to characterize the resultant nitrided surface and layers. The results showed that fluidized bed process can be used to produce a precipitation-free nitrided layer characterized by the S phase or expanded austenite on austenitic stainless steel at temperatures below 500°C. But there exists a critical temperature and an incubation time for effective nitriding, below which nitriding is ineffective. The corrosion behaviour of the as-nitrided surfaces is significantly different from that previously reported for low temperature plasma nitriding. This anomaly is explained by the formation of iron oxide products and surface contamination during the fluidized process.
QPQ Salt Bath Nitriding and 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 strengthening technology which contains mainly salt bath nitriding and salt bath post-oxidizing processes. The effect of nitriding temperature and duration on the corrosion resistance of QPQ treated specimens is explored by immersion tests and salt spray tests in this paper. The material used in this study was 1020 annealed 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 a 5% NaCl neutral solution. The data indicate that, when the nitriding duration is less than 2 hours at temperature below 590(phase change will exist when the nitriding temperature is above 590 according to Fe-N phase diagram) , the higher temperature of the salt bath nitriding , the specimens will have the higher corrosion resistance. In addition we have found that nitriding for too short a time generates a thin compound layer, and nitriding for too long generates too much porosity. Both will deteriorate the corrosion resistance.
Gas Quenching with Helium
Authors: Stratton Paul , Shedletsky Igor , Lee Maurice
Published: March 2009

Gas quenching in vacuum furnaces is an increasingly attractive option because it has a
low environmental impact and the least distortion of parts being treated. Whilst nitrogen is by far
the most common quenching gas, helium is a viable option where higher cooling rates are required,
particularly for carburised components. This paper explores the improvements in gas quenching
technology that allow components manufactured from standard carburising steels to be quenched
with high-pressure helium and illustrates the improvements it offers over high pressure nitrogen
quenching. As helium is an expensive rare gas, recycle systems make its use more economically
attractive. The factors that need to be taken into account when designing such systems, including
the necessity for purification, are discussed. Sources of helium and the means of delivery,
particularly in Asia, are also covered.
Adhesion Strength between D.C. Plasma Nitrided Steels and CrN Films
Authors: Kondo Kyouji , Ikenaga Kaoru , Funaki Yoshiyuki , Takeuchi Hirotsugu
Published: March 2009

The hard ceramic film made by PVD is used to increase the life and wear resistance of tools
and dies. The adhesion strength between the ceramic film and surface of steels is important in ceramic
coating of tools and dies. We investigated the adhesion strength between nitrided tool steel for dies
SKD61 (JIS) and CrN film. The steel was plasma nitrided with 20 vol% N2 - H2 gas, and coated with
CrN by means of PVD of HCD type. Thicknesses of the CrN films are 1 - 6 μm. Plasma nitriding time
and thickness of the CrN films was examined to investigate adhesion strength between the CrN film
and the steel. Maximum critical load value 55N at nitriding time 7,200 sec was obtained from the CrN
coating on the surface of plasma nitrided SKD61
Synthesis and Characterization of Ti-Cx-N1-x Coatings Prepared by Arc Ion Plating
Authors: Choi Eun Young , Jang Chul Sik , Kang Myung Chang , Kim Kwang Ho
Published: March 2009

Ternary Ti-Cx-N1-x coatings were deposited on stainless steel substrates by arc ion plating (AIP) technique using Ti target at the temperature of 300 with a negative substrate bias voltage of -25 V. The carbon content in Ti-Cx-N1-x coatings linearly increased with increasing CH4/(CH4+N2) gas flow ratio at a constant arc current of 60 A. The microstructure and mechanical properties such as micro-hardness and average friction coefficient of Ti-Cx-N1-x coatings were investigated as a function of carbon content. As the carbon content in Ti-Cx-N1-x coatings increased, the microhardness values of Ti-Cx-N1-x coatings increased from 20 GPa for TiN coatings and reached the maximum value of approximately 32 GPa at x=0.52 in Ti-Cx-N1-x coatings. The variation of microhardness of Ti-Cx-N1-x coatings had a relationship with the change of residual stress. The average friction coefficient of Ti-Cx-N1-x coatings largely decreased with increasing carbon content.
Numerical Analysis Method for Temperature Distribution in Cylindrical Steel during Quenching Process
Authors: Fukuya Michiaki , Terasaki Toshio , Hasegawa Kouki , Kitamura Takanori
Published: March 2009

The technics for predicting thermal cycle of a quenching by using the finite element method have
been studied by comparing theoretical values with numerical analysis results. The basic equation of a
minimum element length for cylinder thermal cycle was proposed, which was able to calculate from
informations such as an initial temperature, a radius of cylinder, a heat transfer coefficient and the aimed
temperature change at the cylinder surface. The minimum time increment for guaranteeing accuracy was
given corresponding to the minimum element length. It was shown that the minimum element length for pipe
thermal cycle was replaced by that of cylinder. Temperature distribution in cylinder during quenching process
can be sufficiently predicted by the finite element method with the above, mentioned minimum element
length and the minimum time increment.
Simulation of Induction Hardening Process of Sintered Metal Shafts
Authors: Miyachika Kouitsu , Koide Takao , Oda Satoshi , Motooka Naoki , Uemoto Keiichi , Matsumoto Yoshihisa , Namba Chiaki , Mada Hidefumi , Tsuboi Hajime
Published: March 2009

A FEM simulation program for induction hardening of sintered metal shafts was made up.
Physical properties of the sintered metal were measured. An electromagnetic field analysis, a heat
conduction analysis and an elastic-plastic stress analysis during the induction hardening process of
sintered metal shafts were carried out for various hardening conditions by using the measured material
data and the simulation program. The effects of the electric power and the frequency on the temperature
and the stress during the induction hardening process of the sintered metal shaft and the residual stress
were examined. The map for selecting the optimum heating condition (P, f) for the residual stress of
the sintered metal shaft due to the induction hardening was indicated.
Numerical Simulation of Residual Stress in Cu-Fe-P Alloy
Authors: Hua Su Juan , Ping Liu , Ming Dong Qi , Jun Li He , Ying Xu Ying
Published: March 2009

The residual stress distribution of microstructure about Cu-Fe-P alloy for lead
frame is simulated by finite element method of elastic-plastics deformation. The effect of the
density of Fe particle on residual stress is mainly analyzed. It is indicated that the larger the
density of particle is, the larger residual stress in particle and matrix near the interface is, and
the larger stress difference between both the sides is. When the density of Fe particle is 35%
and the compressive extent of cold rolling is 25%, in the X-direction, the stress variation of
the Cu matrix is from compressive 900MPa to tensile 1480MPa, and stress of the Fe particle
is about compressive 246MPa. The maximum residual stress gradient near the interface
between Cu matrix and Fe particle reaches 1726MPa. The bigger stress concentration and
residual stress will destroy the quality of the material. Even peelings on the surface occur. So
the appearance of bigger Fe particle goes against the quality of the material, and it should be
avoided as far as possible in the production of Cu-Fe-P alloy for lead frame.
In Situ Neutron Diffraction during Thermo-Mechanically Controlled Process in Low Alloy Steels
Authors: Koo M.S. , Xu Ping Guang , Li J.H. , Tomota Yo , Muransky O. , Lukáš Petr , Adachi Yoshitaka
Published: March 2009

A challenge was made to examine the micro-structural evolution during thermomechanically
controlled processing (TMCP) by in situ neutron diffraction. Since the neutron beam
is too weak to achieve a time-division measurement to follow a rapid transformation in alow
carbon steel, 2%Mn was added to make the austenite to ferrite transformation slower. Round bar
specimens were heated up to 900°C with an electrical resistance method, then cooled down to
700°C, and compressed by 25% followed by step-by-step cooling. During the step-by-step cooling,
neutron diffraction profiles were obtained and the volume fraction of ferrite, phase stresses and
FWHM were analyzed. Using a similar TMCP simulator, specimens were quenched into water at
several stages of the heat schedule to freeze the corresponding microstructures, which were
observed with OM and SEM. As results, the ferrite volume fraction determined by neutron
diffraction on cooling agrees well with that by microscopy. It is found that the austenite deformation
and/or Nb addition accelerate the ferrite transformation to result in finer grain size.
Neutron Diffraction Measurement of Thermal Residual Stresses Caused by Solution Treatment for a SUS 304 Stainless Steel Mechanical Part
Authors: Matsushima M. , Jin X.J. , Shiota Y. , Tomota Yo , Suzuki Hiroshi , Moriai Atsushi
Published: March 2009

Neutron diffraction technique was employed to measure stress distribution in an interior
region of a SUS304 rotating mechanical component with a fringe after solution treatment and after
subsequently conducted stress-relief annealing. A coupon with 3x3x3 mm was prepared by spark
cutting to determine stress-free spacing d0. The elastic strain was determined by using the measured
(111) spacing d and d0 by (d - d0)/d0. Then the obtained strains were input into the general Hooke’s
law to calculate stresses. The residual hoop stress near the surface is compressive which is lowered
in the inner part. The residual stresses near the center of the component are hydrostatic tensile
stresses. These residual stresses were not relaxed by the annealing treatment recommended in a
handbook. Hence, more appropriate stress relief treatment has to be developed. In case of a cast
specimen, coarse grains with a strong texture made it difficult to determine residual stresses
precisely.
The Present and Future of Hardness Standard Blocks
Authors: Yamamoto Takashi
Published: March 2009

Looking at the current status of hardness standards, we occasionally come across the view that it
is sufficient that hardness measurements can be matched somewhat forcibly to the hardness values of
standard blocks. However, if the direct accuracy of a hardness tester and indenter and loading conditions are
well managed and appropriate testing procedures are taken, the measurement of hardness should naturally
agree with the value indicated on a standard block, and “hardness” should be an industrial quantity obtained
in that way. Therefore, we should recognize anew the original purpose of a hardness standard block as a
standard tool, such as the daily inspection (indirect verification) of a tester and/or whether testing practices
are under proper management, as well as to make a comparison between testers and/or between indenters.
From this standpoint, we, in the capacity of a dedicated test-block manufacturer, discuss the principles of
hardness test methods, the uniformity, durability and trends of hardness standard blocks, and future hardness
standards relative to the ISO standards, based on our past results from testing and experiments with a number
of standard blocks.
Influence of Thermo-Mechanical Heat Treatment on the Thermoelectric Properties of Ag Added Bi1Sb3Te6 Compounds
Authors: Min Wang Kee , Hwang Sung Doo , Lee Chang Ho , Park Young Do , Park Yong Ho , Park Ik Min
Published: March 2009

The direct extrusion process using the mechanically alloyed powder as raw materials was
applied to prepare the thermoelectric materials. The mechanically alloyed powders of Ag added
Bi1Sb3Te6 were extruded using pulse discharge sintering method at temperatures ranging from
345°C to 425°C. The fractographs of extruded specimens shows that no grain size changes was
observed until 385°C, but became coarser with the increase of the extrusion temperature above
405°C. The X-ray diffraction patterns showed that the intensity of (110) plane increased with
extrusion temperature up to 385°C and started to drop down above 405°C. The power factor value
(PF) also increased with the extrusion temperature up to 385°C and altered above 405°C. These
trends agreed with the variation in intensity of (110) plane of XRD patterns. The figure of merit (Z)
value of the extruded specimens at 385°C was 3.1 × 10-3 W/K, which was the highest value among
the prepared specimens.
Microstructural Characterization of Creep Damaged 11Cr-3.5W-3Co Steel
Authors: Kim C.S. , Kwun S.I. , Ahn Bong Young , Nahm Seung Hoon , Lee Seung Seok
Published: March 2009

The effects of the precipitate and martensite lath on the softening behavior have been
investigated for 11Cr-3.5W-3Co steel during creep at 700. During creep, the precipitate on the
PAG (prior austenite grain) boundaries and martensite lath boundaries coarsened. The recovery of
dislocation density and an increase of martensite lath width took place. It is shown that the inverse of
the size of the precipitates and the inverse of the square root of the martensite lath width have a linear
relation with the Vickers hardness, which corresponds to the Hall-Petch relation and particle looping
mechanism.
Effect of Microstructure on Martensitic Transformation and Cyclic Deformation Characteristics in a Cu-Al-Ni Based Alloy with Unidirectionally Solidified Structure
Authors: Yang Gon Seung , Kim K.H. , M Kabilan , Jee Kwang Koo , Jang Woo Yang
Published: March 2009

The effect of the betatizing conditions on microstructure, transformation characteristics
and pseudoelastic behavior has been studied in an unidirectionally solidified Cu-Al-Ni based alloy.
The coarse γ2 phase is precipitated in the cast-rod betatized at 650 and the volume fraction of it
is decreased by increasing the betatizing temperature above 700 . However, a small amount of γ2
phase is left behind despite betatizing at 800 . No martensitic transformation takes place in the
cast-rod betatized at 650, because the precipitation of γ2 phase leads to stabilization of β1 parent
phase. However, β1→β1′ martensitic transformation occurs in the cast-rod betatized at 700 and
both β1→β1′ and β1→γ1′ martensitic transformations concurrently undergoes in the cast-rod
betatized above 750 because of the slope of Al concentration nearby γ2 phase. The loaddisplacement
loop of the as-cast rod betatized at 750 is linear, but those of the as-cast rods
betatized at 800 and 850 are non-linear showing the typical pseudoelastic loop and the
deformation is completely recovered upon unloading.
Effect of Surface Condition on Melt-Out of Die-Casting Mould
Authors: Youn Kuk Tae , Na Young Sang , Lee Jong Hoon , Rhyim Young Mok , Yoo Wee Do , Lee Chan Gyu
Published: March 2009

In order to understand the melt-out mechanism of H13 die casting mould material,
microstructural investigation was conducted for the immersion-tested surface in Al-alloy melt. The
surface condition of H13 tool steel was modified by varying nitriding conditions and by surface
blasting. In particular, long-term behavior of melt-out phenomena during immersion testing of up to
43 hours was focused in this article. It was observed that an ion-nitrided H13 surface showed higher
resistance towards melt-out than a gas-nitrided or blasted surface. This was related to the surface
layers that are normally formed by nitriding.
The Effect of Slip Conditions on the Contact Fatigue Strength for Pitting of a Carburized Steel
Authors: Makino Taizo , Horimoto Masayuki , Matsumoto Hitoshi
Published: March 2009

The objective of the present study is to clarify the effect of slip conditions, such as slip ratio, outer surface velocity, and lubricant oil temperature on the contact fatigue strength for pitting (pitting strength) of carburized steels. Rolling contact fatigue (RCF) tests were conducted under oil lubrication on 26mm-diameter specimens made of a carburized steel with various combinations of slip ratio, outer surface velocity, and lubricant oil temperatures. Relationships among those three parameters were also evaluated. The pitting strength decreased with the increase of slip ratio, with the decrease of outer surface velocity, and with the decrease of lubrication oil temperature. It was found that the slip ratio, the outer surface velocity, and the lubricant oil temperature influenced the friction coefficient and the contact surface temperature. The friction coefficient increased when slip ratio increased. The friction coefficient was considered to be the dominant factor which directly affected the pitting strength.
Annealing Effect on the Thermoelectric Properties of Undoped CoSb3
Authors: Kim Il Ho , Lee Jung Il , Ur Soon Chul , Jang Kyung Wook , Choi Good Sun , Kim Joon Soo
Published: March 2009

Binary skutterudite CoSb3 compounds were prepared by the arc melting and hot pressing processes and their thermoelectric properties were investigated at 300K-600K. Annealing effect was examined and it was correlated to phase transformation and homogenization. Thermoelectric properties of the arc-melted and hot-pressed CoSb3 were discussed and compared. Undoped CoSb3 prepared by the arc melting showed p-type conduction and metallic behavior at all temperatures examined. However, hot pressed specimens showed n-type conduction, possibly due to Sb evaporation. Thermoelectric properties were remarkably improved by annealing in vacuum and they were closely related to phase transitions.
Study of Fe-Ni(Cr) Alloy and Nano-Al2O3 Particles Composite Coating Prepared by Laser Cladding
Authors: Hua Yeo Jian , Wei Zhang , Xia Gao Ming , Li Zhang Qun
Published: March 2009

The experiments of laser cladding Ni-coated nano-Al2O3 powder were made on 2Cr13 stainless steel using 7kW CO2 laser processing system. The microstructure and mechanical characteristics of composite coating were tested by scanning electronic microscope (SEM), X-ray diffraction (XRD), energy dispersion analyzer of X-ray (EDAX) and microhardness tester. The results showed that the composite coating was composed of superfine cellular dendritic structure. The X-ray diffraction data revealed that the cellular grains were composed of nano-Al2O3 particles, iron nickel alloy and iron chromium alloy. The mechanical characteristics of composite coating greatly increased. Compared with parent metal, the average hardness of composite coating increased by 1 time, and its wear property increased by 1.25 times.