bluuebunny/crossref_metadata_2025 huggingface dataset:
New Process-Microstructure Method for Affordable 2024 Series Aerospace Aluminum Alloys
Authors: Eto Takehiko , Nakai Manabu
Published: March 2009

New affordable 2024 series aerospace aluminum alloy has been developed. Fracture toughness has
been demonstrated increase in inverse proportion to the root of the distance between constituents,
Cu2FeAl7, formed during ingot solidification. Higher fracture toughness material is obtained by
means of combination of reduction of Fe content and wider spacing between the constituents. The
fractured surface of those materials has been confirmed to show larger dimples due to the wider
constituents. An outcome is the fracture toughness increases 20% through broadening the space
from 75 to 140μm. Fatigue crack growth (FCG) has been governed by the morphology of
dispersoids such as Cu2MnAl20, Cr2Mg3Al18 and ZrAl3, formed in homogenization process
during heat treatment of ingot. In a low ΔK region, the FCG rate is slower when Cu2MnAl20
becomes larger. It is reconfirmed that the FCG rate is still faster for small dispersoids, Cr2Mg3Al18
or ZrAl3 bearing materials than Cu2MnAl20 bearing one through bridging effect of dispersoids. In a
high ΔK region, on the other hands, the FCG rate becomes slower by broadening the spacing of
the constituents. A new 2024 series alloy (2x24) with high fracture toughness and excellent FCG
resistance has been developed on the basis of process- microstructure-structure methods.
Study on a Damage Tolerant Titanium Alloy
Authors: Hui Song Xiao , Mi Xu Jun
Published: March 2009

Titanium alloys are subject to high expectation of damage tolerance in terms of high fracture
ductility and low rate of fatigue crack propagation to suit the preference in material consideration for
aircraft manufacture. This paper reviews the researches in damage-tolerant medium- and high-strength
titanium alloys.
Microstructures and Cohesiveness of Alkali- and Heat-Treated Films on a Ti-15Zr-4Nb-4Ta Alloy
Authors: Kobayashi Sengo , Murakami Koji , Nakai Kiyomichi , Hino Makoto
Published: March 2009

Microstructures of alkali- and/or heat-treated films on a Ti-15Zr-4Nb-4Ta alloy were
analyzed by means of scanning electron microscopy, thin film X-ray diffraction and Auger electron
spectroscopy. The cohesiveness of films was also evaluated by scratch tests. The films were formed
by immersion in 5M aqueous NaOH solution at 60 °C for 86.4 ks (alkali treatment) followed by
heating at 400–600 °C for 3.6 ks. The film on alloy formed by alkali treatment exhibits the same
strucutre as that formed on an alkali-treated titanium. Compositional gradient of alloying elements, Zr,
Nb and Ta, is detected in the film. The cohesion of alkali-treated film is considerably increased by the
heat treatment, and the maximum cohesion is obtained by heating at 600 °C. The increase in cohesion
of alkali-treated film by heat treatment is due to both the diffusion of Zr into film and the formation of
sodium titanate on substrate.
Metallurgical and Mechanical Properties of Friction Stir Welded Ultra Fine Grained Steel
Authors: Hirano Satoshi , Okamoto Kazutaka , Park S.H.C. , Aota K. , Tsukamoto T.
Published: March 2009

Friction Stir Welding (FSW) has been applied to ultra fine grained (UFG) steel which is the plane
carbon steel with the average grain size of 1mm. The plates of 5mm thickness was successfully welded using
pcBN tool (polycrystalline cubic boron nitride) and the metallurgical and mechanical properties of the joint
were evaluated. In the stir zone, Bainite has been formed which shows the highest harness in the joint. On the
other hand, grain growth is observed in the heat affected zone. The joint effect of 88% has been obtained for
UFG steel by FSW process.
Enhancement of Formability in Magnesium Alloy AZ31B via Friction Stir Processing
Authors: Sato Yutaka S. , Sasaki A. , Sugimoto A. , Honda A. , Kokawa Hiroyuki
Published: March 2009

Mg alloy has a poor formability at room temperature because of lack of the active slip
systems, but the grain refinement improves its ductility. Friction stir processing (FSP) can create
homogeneous microstructure consisting of fine grains in Mg alloys, thus it would be expected that
FSP enhances the formability of Mg alloys. In this study, multi-pass FSP was applied to Mg alloy
AZ31B, and then formability of FSPed alloy was evaluated. Multi-pass FSP produced the fine
recrystallized grains in Mg alloy. The stir zone exhibited larger fracture limit major strains than the
base material under uniaxial tension and plane strain deformation, and these values increased with
decreasing grain size. The stir zone having grain size of 2.9 μm showed the fracture limit major
strains which are roughly as same as those of an annealed pure Al. The present study suggests that
FSP is an effective method to enhance the formability of Mg alloys.
Effect of Fe Content on Hot Tearing of High-Strength Al-Mg-Si Alloy
Authors: Nagaum Hiromi , Suzuki Satoru , Okane T. , Umeda T.
Published: March 2009

The effect of Fe content on hot tearing of the high-strength Al-Mg-Si alloy was
systematically investigated. In this study, a thermodynamic calculation software Thermo-Calc was
used to calculate the solidification path under the non-equilibrium condition, and the mechanical
properties of this alloy have also been investigated during solidification using an electromagnetic
induction heating tensile machine. In order to confirm the calculation results of solidification path, a
quenching test also was carried out. By using the Thermo-Calc, the sequence of crystallization,
crystallization temperature of formed phases and their crystallized amount were systematically
investigated for each alloy in which Fe content was changed. Furthermore, by comparing the fracture
surfaces of the tensile testing sample and DC billet, the temperature range of crack initiation of the
alloy was examined. Comparing the temperature range of crack initiation with the crystallization
phase and its crystallization order, Fe content of high-strength Al-Mg-Si alloy influenced hot tearing
significantly owing to the crystallization behavior of α(AlFeMn).
Microstructural Evolution and Performance of Friction Stir Welded Aluminum Matrix Composites Reinforced by SiC Particles
Authors: Ma Z.Y. , Feng A.H. , Xiao B.L. , Fan J.Z. , Shi Li Kai
Published: March 2009

The effect of friction stir welding (FSW) parameters on microstructure and properties of
15vol.%SiCp/2009Al composite welds was investigated at tool rotation rates of 400-1000 rpm for a
constant welding speed of 50 mm/min. 8mm thick defect-free welds were produced at higher tool
rotation rates of 600-1000 rpm, whereas an unwelded seam was distinctly visible at the root of plates
at a lower tool rotation rate of 400 rpm. FSW resulted in generation of fine and equiaxed recrystallized
grains of ~6 μm and significant improvement of SiC particle distribution in the weld nugget. Under
as-FSW condition, the hardness of the weld nugget was significantly higher than that of as-extruded
parent material. Furthermore, tensile and yield strengths of as-FSW composite welds in both the
longitudinal and transverse directions were superior to those of as-extruded parent material.
Post-weld T4 temper resulted in limited grain growth due to the pinning of SiC particles. Under the
T4 condition, the tensile strength of the welds along the longitudinal and transverse directions reached
82 and 95% of the parent material, respectively.
The Oscillation Behaviour of Liquid Metal in Arc Welding
Authors: Hermans M.J.M. , Yudodibroto B.Y.B. , Hirata Yoshinori , den Ouden G. , Richardson I.M.
Published: March 2009

This paper gives an historic overview and new developments of research activities in
the field of the oscillatory behaviour of liquid metal in arc welding.
Early work focused on the oscillation behaviour of the weld pool in Gas Tungsten Arc Welding
(GTAW). Agitated weld pools exhibit specific modes of oscillation, the frequency of which can
be measured from the arc voltage data and is conditioned by the geometry of the weld pool and
the properties of the liquid metal. Of technological interest is the alteration of the oscillation
behaviour for partially and fully penetrated situations, which can be used for penetration control
during welding.
A logical extension of the research activities was related to the influence of filler wire addition
on the oscillation behaviour. An intermediate step towards the description of Gas Metal Arc
Welding (GMAW), is the situation of GTAW with cold filler wire supply. It was found that both
the liquid weld pool and the pendant liquid droplet at the tip of the filler wire experience an
oscillation, which obscures the influence of the individual contributions of both liquid masses on
the voltage data. It was shown that online penetration control is still possible, provided that the
metal is transferred in an uninterrupted way, i.e. the filler wire flows smoothly into the weld
pool.
For GMAW, in which detached droplets collide with the weld pool surface, the difficulties are
even more prominent. Recent work is related to this issue. Monitoring of the phenomena
occurring at the weld pool and the pendant droplet become problematic by means of the voltage
data. Observations by means of high-speed video imaging will be discussed.
Apart from the experimental studies, efforts are undertaken in numerical simulations of the
processes. A good correlation is obtained between experimental data and the results of the
numerical models.
Selection and Design of Brazing Fillers for Metal-Ceramic Joints
Authors: Bissig Vinzenz , Janczak-Rusch Jolanta , Galli Matteo
Published: March 2009

Three different approaches for metal to ceramic brazing are compared using the example of
Si3N4/TiN-steel joints: the use of an active filler metal (single layer brazing system), the
metallisation of the ceramic and brazing with a non active filler (two-layer brazing system), the use
of a composite brazing filler system (three layer brazing system). Different aspects are analysed: the
development of the joint’s microstructure in the as-brazed state, the thermally induced residual
stresses and the resulting bend strength of the joint’s strength.
With two layers and three layers brazing system, bend strength of about 400 MPa, about 15%
higher then single filler metal, were achieved. The three layer brazing system has two advantages:
firstly one step processing secondly lower scattering of joint bend strength compared to two layers
brazing system.
The key factors in all cases are the selection of the brazing fillers and the braze design. In all cases a
careful selection of the brazing fillers and the braze design are the key factors. The first criteria for
the selection of the brazing fillers for joints of dissimilar materials can be done by considering only
the main filler characteristics like titanium content, processing temperature and yield stress. It’s
necessary to simulate the joint behaviour by finite element simulation for verifying the final
selection of filler metals. It was clearly seen that the plasticity of the filler metal is the main factor
affecting residual stresses for the joint geometry in this current work.
Laser Grooving and Welding of Cracks Occuring at Dies for Die Casting
Authors: Tušek Janez , Taljat B. , Hrženjak Marco , Klobcar Damjan
Published: March 2009

The paper treats the application of laser to repair of cracks occurring at dies for die
casting of non-ferrous metals (particularly aluminium, magnesium and their alloys). The first part
describes a suitable laser unit enabling crack grooving and then welding. An Nd:YAG laser source
is shown with its equipment for laser-beam transfer, control and directing of laser-beam focus. Dies
for die casting are made of quality steels and are of very complex shape. As far as their repair is
concerned this means that they are to be welded at their edges, corners, narrow gaps and vertical
walls, i.e. in various positions and in various directions. In the second part the grooving technology
is described, and in the third part laser welding of grooved cracks using a filler material, i.e., a thin
welding wire. At the end some conclusions are drawn. It is stated that from the viewpoints of
technology and economics, it is sensible to laser groove and then weld the thermal cracks with a
suitable material. The filler material should have such a chemical composition that after welding a
weld having adequate mechanical properties, without any additional heat treatment, is obtained.
Evaluation of Friction Spot Joining Weldability of Al Alloys for Automotive
Authors: Chang Woong Seong , Cho Hyeon Jin , Kim Heung Ju , Chun Chang Keun
Published: March 2009

In an attempt to optimize the friction spot joining process of Al alloys for automobiles (Al
5000 and Al 6000 series, thickness 1mm), effects of joining parameters such as tool rotating speed,
plunging depth and dwelling time on the weld joints properties were evaluated. Experimental tests
were carried out for lap joined Al plates. A wide range of joining conditions could be applied to join
Al alloys for automobiles without defects in the weld zone except for certain welding conditions with
an insufficient heat input. The microstructures and hardness variations in the weld regions are
discussed. The microstructures of welds, corresponding to the pin hole, have dynamic-recrystallized
grain similar to stir zone in FSW weld. In hardness distribution, minimum hardness region was
located about 6-mm away from the weld center, corresponding to the shoulder radius of the tool. For
each weld the results from tensile-shear tests are also presented. For sound joints without defects,
tensile shear strength of weld joints was higher approximately 230% than acceptable criteria of tensile
shear strength of electrical resistance spot-welded joints for aluminum (MIL-W-6858D).
Microstructural Design for Advanced Structural Steels
Authors: Bouaziz Olivier , Embury J. David
Published: March 2009

In this work we have outlined the use of micromechanical models which
can rationalize the behaviour of a number of structural steels by including both static
and dynamic length scales and considering the interaction of the phases. The
approach treats the steels as composites but includes the influence of both volume
fractions and physically based length scales and processes. In essence it can be
extended to utilise the methodology outlined by Ashby&al. to include length scales in
the development diagrams of composite materials.
Study of the Development of Heterogeneous Grain Size in the Through-Thickness Direction of Hot Rolled ELC Steels
Authors: Leysen Frans , Penning Jan , Houbaert Yvan
Published: March 2009

The present study aims to investigate the mechanism of the development of abnormal
grain sizes in the through-thickness direction of hot rolled steel strips. For this purpose, industrially
prepared steel strips were further hot rolled in a laboratory hot rolling mill, setting a variety of
rolling parameters. As found, the deformation rate in the hot rolling practice exerts an important
role in explaining the mechanism of abnormal grain growth, especially in the close vicinity of the
strip surface. Furthermore, the influence of the cooling penetration depth, induced by the roll
contact was examined closely, as this phenomenon might support abnormal grain growth
mechanisms. Additional information was found in performing a texture analysis in the throughthickness
direction of the steel strips, in accordance with the optical metallurgical survey of the
microstructures.
It will be shown that, the combination of particular hot rolling parameters provokes the occurrence
of abnormal grain growth in the through-thickness direction of the ELC steel strips. These
particular conditions were considered to be related to the finish hot rolling temperature and thus the
roll cooling penetration depth imposed on the steel strip, the finishing reduction degree and
especially the strain rate conditions. Moreover, the observed abnormal grain growth is sensitive to
the coiling temperature applied.
From the experiments, it can be concluded that the mechanism of the formation of a large grained
ferrite band below the strip surface is strongly influenced by the development of a fine-grain ferrite
layer at some distance below the strip surface. The existence of this layer of very small ferrite
grains can be explained on the basis of texture analysis and calculations based on literature data. In
this way, it was considered that dynamic recrystallisation of austenite at some depth below the steel
strip surface is of most significance in supporting the development of abnormally large ferrite
grains. In this paper, further considerations on the mechanism of the abnormal grain growth
phenomenon will be dealt with.
Mechanism of Hydrogen Embrittlement of Austenitic Steels
Authors: Shivanyuk V. , Gavriljuk Valentin , Foct Jacques
Published: March 2009

Three main hypotheses of hydrogen embrittlement (HE) of austenitic steels are
discussed based on the studies of the interatomic interactions, hydrogen-induced phase
transformations and dislocations properties. Measurements of electron spin resonance and ab initio
calculations of the electron structure witness that the concentration of conduction electrons
increases due to hydrogen, which enhances the metallic character of interatomic bonds. The
hypothesis of brittle hydrogen-induced phases is disproved by the studies of the silicon-alloyed
steels: the silicon-caused increase in the fraction of the εH martensite is accompanied by the
decrease of HE. Studies of strain-dependent internal friction have shown the hydrogen-caused
decrease in the start stress of microplasticity and increase in the velocity of dislocations in
accordance with HELP hypothesis. A mechanism of HELP is proposed based on the hydrogencaused
enhancement of the metallic character of interatomic bonds, which results in the local
decrease of the shear modulus within the hydrogen atmospheres round the dislocations. As
consequence, the line tension of the dislocations followed by the hydrogen atoms decreases, which
finds its expression in the early start of dislocation sources, decreased distance between
dislocations in the pile-ups and increased velocity of dislocations. A mechanism of localization of
plastic deformation is proposed based on the observations of the hydrogen-enhanced concentration
of equilibrium vacancies.
Influence of Vacancy Formation and Mg Migration on Cracking in Spot Welding AA5754 Alloys
Authors: Wang Xiao Wei , Zhang Hong Yan , Sun Ai Qing
Published: March 2009

Al alloys with Mg as the major alloying element constitute a group of non-heat treatable alloys with
medium strength, high ductility, excellent corrosion resistance and weldability. However, the segregation of Mg
may adversely affect the performance of these materials if they are exposed to rapid heating and cooling
environments such as resistance spot welding. The formation and migration of vacancy is an important factor
affecting Mg segregation. In this paper, the amount and distribution of Mg were measured by electron probe
microanalysis and the vacancy formation energy in AA5754 alloys was measured by positron annihilation
lifetime spectroscopy. The results indicated that the segregation of Mg at cracks, occurring under suitable
temperature and stress conditions, is related to the formation and migration of vacancies, and may promote crack
initiation and propagation.
On the Phase Transformations in Hot Rolled TRIP-Assisted Multiphase Steels
Authors: Godet Stéphane , Georges C. , Jacques Pascal J.
Published: March 2009

TRIP-assisted multiphase steels exhibit an excellent balance of strength and ductility,
which makes them very attractive for the automotive industry. These remarkable mechanical
properties can be attributed mainly to their composite-like microstructures and to the transformation
of retained austenite into martensite during straining (Transformation-Induced Plasticity). The aim
of this study is to highlight the interactions between the hot rolling conditions, the transformation of
austenite and formation of the microstructure, and the resulting mechanical properties. Various
rolling simulation techniques were employed to determine how the composite microstructure is
formed during the various steps of multi-stage thermomechanical processing.
Steel Sheets Mechanical Properties Improvement
Authors: Traino A. , Baschenko A. , Zavrazhnov A. , Ivoditov Vadim
Published: March 2009

Innovative technological processes for a new integrated deformation-thermal production
of flat rolled stock imparting enhanced physical-mechanical properties while minimized alloy
additions has been developed on the basis of recently discovered metallophysical laws of influence,
through hot plastic rolling deformation, upon microstructure-phase conversions and states of steel in
metallurgical products.
Workability and Straining Behaviour of High Silicon Steels (3.0-6.3%Si) by Hot Torsion and RT Compression Tests
Authors: Ros-Yáñez Tanya , Rodriguez-Calvillo Pablo , Colas R. , Houbaert Yvan
Published: March 2009

High silicon steel (up to 6.5 wt.-%Si) is important for the electrical industry because of
its magnetic properties. However, its production in low thickness by cold rolling is difficult due to
extreme brittleness, mainly caused by ordering processes, making dislocation motion more
complex. Nevertheless, these materials appear to be deformable at higher temperatures. The cooling
rate after hot deformation, the temperature from which it is cooled and the time delay prior to cold
deformation are important elements for the understanding of their workability.
Hot torsion tests were performed on Fe-Si steel (4.2 and 5.6 wt.-%Si) under continuous cooling to
study the influence of strain and interpass time on ordering and non-recrystallization temperatures.
Compression tests at a constant strain rate were used to study the effect of continuous cooling to RT
and the delay time between deformations for series of silicon alloys (from 3.3 to 6.3 wt.-% Si) with
different thermomechanical treatments. An aging phenomenon due to an ordering reaction at RT
was observed. Finally, extrapolating the hot torsion and compression tests parameters to the rolling
mill a suitable schedule for hot rolling was found guaranteeing good conditions for further cold
rolling.
Saw Welded Joints of Two API Steels Subject to SCC Laboratory Testing
Authors: Martins Franc A. , Ponciano J.A. , de S. Bott Ivani
Published: March 2009

Many steels tubes used in the Oil Industry are constantly exposed to hydrogen sulphide
(H2S) which can lead to the diffusion of hydrogen into the steel, potentially provoking hydrogen
embrittlement and/or stress corrosion cracking. Additionally the critical region in pipelines is
usually considered to be the welded joints. In this work SAW welded joints of two API steels,
grades X80 and X70, were evaluated using laboratory tests according to the NACE TM0177/96
METHOD A Standard and the slow strain rate test (SSRT) using a sodium thiosulphate solution.
The results indicate that both steel grades can be susceptible to HE and SCC, since loss of ductility
when submitted to SSRT and failure under NACE TM0177/96 METHOD A were observed.
Microstructural Aspects by Electron Microscopy Observed in Al-Mg Based Alloys after Special P/M Processes
Authors: Monteiro Waldemar Alfredo , Buso S.J. , Almeida Filho A.
Published: March 2009

In the last decade light materials have been studied thoroughly and used in
components of pieces in the automobile, naval and aerospace industries. Their
application makes possible mass reduce, load capacity increase, improvement in the
mechanical properties when it is possible. Aluminium-magnesium alloys present good
mechanical properties at moderate mechanical efforts (400 to 700 MPa) and good
corrosion resistance. The alloys in study (Al-2Mg-0.6Zr and Al-2Mg-1Nb) were made
by powder metallurgy (P/M) techniques, employing hot compactation and extrusion
processes followed by cold work and thermal treatments. The analysis by SEM and
TEM shows an evolution in the microstructure of precipitates with the increase of the
time of thermal treatment, according to literature. The distribution of the precipitates in
both alloys was observed and identified by EDS microanalysis (SEM and TEM).
On the Formation of a Non-Traditional Pearlite Morphology
Authors: Damm E. Buddy , Hackenberg Robert E. , van Tyne Chester J.
Published: March 2009

Continuous cooling and isothermal dilatometry was performed for a binary Fe-0.3C alloy
and a ternary Fe-0.3C-1.0Mn alloy at slow (< 0.1 oC/s) cooling rates and isothermally at temperatures
below the equilibrium eutectoid reaction temperature but above the bainite start temperature (625 to
715 oC). Some of the test conditions produced an unusual morphology in which fine scale
‘sub-grains’ are decorated with carbide, with additional discrete carbide particles inside the
‘sub-grains’. A detailed investigation into the network carbide formation indicates formation during
austenite decomposition, as opposed to a post lamellar transformation coarsening or spheroidization
reaction, but only for select temperatures, and apparently only during isothermal conditions.
Recrystallization and Spheroidization Behavior of High Carbon Pearlitic Steels Investigated by Means of Orientation Imaging Microscopy
Authors: Lee Kyoo Young , Im Young Roc , Kestens Leo A.I. , Kim Gyo Sung
Published: March 2009

The microstructural evolution and the softening behavior of hot rolled and 60% cold rolled
0.85wt% carbon pearlitic steels during spheroidization annealing have been investigated by using the
textural and microstructural information contained in the Orientation Imaging Microscopy (OIM)
scans. The local boundary energy map, recently suggested by the present authors, is used to monitor
the changes of stored plastic strain energy distribution in ferrite during the annealing process, which
shows that the spheroidization process of cementite is finished before the completion of
recrystallization of the 60% cold-rolled high carbon pearlitic steel.
Refinement of Cementite in High Strength Steel Plates by Rapid Heating and Tempering
Authors: Nagao A. , Hayashi K. , Oi K. , Mitao S. , Shikanai N.
Published: March 2009

The precipitation behavior of cementite in low carbon steels at various heating rates from
0.3 to 100 K/s has been studied using a high-frequency induction heating apparatus. The materials
used in this study were steel platesfor welded structures: 610 and 780 MPa class steel plates with a
mixed microstructure of bainite and martensite.Cementite was observed using a carbon extraction
replica method and the hardness and toughness were also examined. When heated at the
conventional slow rate of 0.3 K/s, relatively large cementite particles with an average diameter of
72 nm precipitated at the lath boundaries, whereas when heated at a rapid rate over 3.0 K/s,
cementite precipitated both within the laths and at the lath boundaries, and the cementite was
refined down to an average diameter of 54 nm. With such refinement of the cementite, the
toughness was improved. On the other hand, the hardness was irrespective of the heating rate and
was dependent on the tempering parameter. TEM observations of the cementite precipitation
behavior during the rapid heating process revealed that cementite begins to precipitate at the lath
boundaries at about 773 K and within the laths at about 873 K. It is concluded that rapid heating
especially from 773 to 873 K contributes to the cementite refinement and consequently the
improvement in toughness. The effect of alloying elements such as chromium, molybdenum or
silicon on the cementite growth during the rapid heating and tempering treatment is also discussed.
Behavior Analysis of Environmental Hydrogen in High-Magnesium Al-Mg Alloys by Hydrogen Microprint Technique
Authors: Izumi T. , Itoh Goroh
Published: March 2009

High-magnesium Al-Mg alloys are known to be sensitive to stress corrosion cracking involving
environmental hydrogen, hydrogen invading from the corrosive environment. In this study, the behavior of the
environmental hydrogen in Al-6%Mg and Al-8%Mg binary alloy sheets stretched by 10% during exposure to
3.5%NaCl solution has been investigated by means of hydrogen microprint technique. Microprint image is
observed on one surface while the other surface is exposed to the solution. In both alloys, the silver particles
corresponding to the sites where hydrogen atoms are emitted from the inside of the sheets are shown on the slip
lines. It is shown that the hydrogen atoms are transported with moving dislocations in the alloys.
Processing of Submicron Grained Microstructures and Enhanced Mechanical Properties by Cold-Rolling and Reversion Annealing of Metastable Austenitic Stainless Steels
Authors: Somani Mahesh Chandra , Karjalainen L. Pentti , Kyröläinen Antero , Taulavuori Tero
Published: March 2009

The effects of chemical composition, cold rolling and subsequent annealing parameters
on the reversion of strain-induced martensite to austenite were investigated in three experimental
Mn and Si-free Cr-Ni austenitic stainless steels and two commercial Type 301 and Type 301LN
grades by optical and electron microscopy, X-ray diffraction and magnetic measurements.
Hardness and tensile tests were performed to determine the mechanical properties achieved. In
cold rolling, completely martensitic structure could be obtained in the experimental heats, but only
partially in 301 and 301LN grades at reasonable reductions. Upon annealing, in 301LN the
reversion took place by the nucleation and growth mechanism, and submicron austenite grains
were formed within a few seconds at temperatures above 700°C. In the other steels, reversion took
place by the shear mechanism, and ultra-fine grains were formed by the recrystallization of
austenite at temperatures of 900°C or above. Partial reversion resulted in an excellent combination
of yield strength and elongation in 301LN, and also in 301 such ones were attained in the reverted
structure even before any profound formation of submicron grains.
Retardation of 20%Cr Steel Oxidation with Laves Phase Precipitation
Authors: Ide Shinsuke , Funakawa Yoshimasa , Kato Yasushi , Furukimi Osamu
Published: March 2009

A new method to improve oxidation resistance of ferritic stainless steel was studied.
Increase in oxidation resistance of ferritic stainless steel with laves phase precipitation was
succeeded in addition to the conventional method such as addition of rare-earth element.
Ultra low carbon 20%Cr steels with various niobium content continuously oxidized at
1073-1173K in air. A mass gain with exposure at 1073K decreased with increasing niobium content
and saturated more than 0.1% in niobium content. In steels contained niobium less than 0.1%, mass
gain were also decreased with increase in initial ferritic grain diameter. In steels contained niobium
more than 0.1%, laves phase was observed at the ferritic grain boundary by using transmission
electron microscope. But then a mass gain with exposure at 1173K did not decreased with niobium
content and laves phase was not observed.
On the assumption that oxidation behaviors of steels contained niobium more than 0.1% obey the
parabolic law, the parabolic rate constant obtained at 1173K is similar to that controlled by grain
boundary diffusion, and parabolic rate constant obtained at 1073K is similar to that controlled by
lattice diffusion.
These results suggest that precipitation of laves phase retard growth of oxide film effectively with
suppressing grain boundary diffusion of cation forming oxide film.
TRIP Effect and Deformation Damaging of Metastable Austenitic Steels
Authors: Oettel H. , Glavatskikh M. , Martin U. , Nikulin A.
Published: March 2009

The TRIP – effect in metastable austenitic steels is caused by a moderate local
martensitic transformation, connected with an extraordinary increase e.g. of the uniform elongation
in tensile testing. In this case the martensite formation causes an additional hardening effect,
preventing the local deformation as well as damaging during plastic deformation. The main
conditions of a marked TRIP – effect is a low flow stress in the undeformed state, a high
strengthening exponent, a continuous transformation up to about 20 % martensite and a high
resistance against damaging (e.g. crack formation and propagation). The martensite transformation
starts in glide or shear bands and their crossings also at temperatures clearly above the conventional
Md – temperatures, reducing the stress local concentrations and so preventing damaging.
Furthermore, high martensite contents can be detected along the fracture path, indicating the
hindering of the crack propagation by the transformation. To demonstrate the influence of
damaging on the TRIP – effect the deviations from the so-called Considere-criterion for uniform
elongation can be used. Related to the deformation the damaging under TRIP – conditions is
minimal.
Texture Evolution of Ferritic (AlSl 430) Stainless Steel Strips during Cold Rolling, Annealing and Drawing
Authors: Ferreira Filho A. , Herrera C. , Lima Nelson B. , Plaut Ronald Lesley , Padilha Angelo Fernando
Published: March 2009

The evolution of the crystallographic texture of ferritic stainless steels, starting
from the as received (hot rolled) condition from the steel mill, going through cold rolling,
annealing and final stamping is analyzed in this paper. Two ferritic stainless steels (Nb
stabilized) having a thickness of 3.0 and 0.7mm, have been employed. The thicker one has
been cold rolled to 40 and 73% thickness reduction, annealed at 750 and 850°C for 1 hour.
The thinner one, with a similar composition, has been 77% cold rolled and annealed at
870°C at the steel plant and subsequently submitted to deep drawing in order to evaluate
texture and drawability. Texture has been evaluated using DRX in the as received, cold
rolled, annealed and after drawing conditions. Drawability has been evaluated using tensile
testing in order to obtain the FLC curves. AISI 430 stainless steel, in the as received
condition presented a strong {100} texture in the <110> and <120> directions and the
gamma fiber. After cold rolling, the material presented stronger gamma and weaker alpha
fibers. Annealing of the cold rolled samples conduced to the vanishing of the alpha and
strengthening of the gamma fiber, adequate for deep drawing operations. In spite of the
AISI 430 of 0.7mm having presented a strong gamma fiber, other deep drawing properties
were not adequate and the material cracked during stamping.
The Individual and Cumulative Effect of C and N on the Hardening and Structure of High-Nitrogen Hot Plastic Worked Steels
Authors: Kaputkina Liudmila M. , Prokoszkina W.G. , Siwka J. , Svjażin A.G. , Koczurkiewicz Bartosz , Knapiński Marcin
Published: March 2009

Investigation into the effect of carbon and nitrogen contents of steels with an addition of
chromium, nickel and manganese on their structure and properties after thermoplastic treatment has
been carried out within the present study. For the physical modeling of thermoplastic treatment
processes, a DIL 805A/D dilatometer with a deformation capability and a Gleeble 3800 simulator
were used. The effect of carbon and nitrogen contents and the sum of these elements (C+N) on the
hardening of the material during hot plastic working. The softening of the material depends on the
C/N element ratio. The influence of the constituents under analysis on the dynamics of removal of
cold work effects is different; C speeds up, while N slows down this process. The influence of the
sum of the elements C and N depends on the type of nonmetallic phase precipitates. The structure
and properties of such steels are determined by quenching and tempering cycles.
Atomic Interactions in Stainless Austenitic CrMn Steels Alloyed with C, N or (C+N)
Authors: Shanina B.D. , Gavriljuk Valentin , Berns Hans
Published: March 2009

Measurements of conduction electron spin resonance (CESR) in steel allow to separate
the contributions from free electrons which provide the metallic character of interatomic bonds and
from localized electrons involved in the covalent bonds. The data of the CESR study carried out on
austenitic CrMn steels alloyed with carbon, nitrogen or carbon+nitrogen are presented. It is shown
that, in contrast to carbon, nitrogen enhances the metallic character of atomic interactions with a
maximum of the concentration of free electrons at some critical content of nitrogen (about 2 at.%).
The combined alloying with carbon+nitrogen leads to two effects: (i) a larger concentration of free
electrons and (ii) a shift of the critical content of interstitials towards higher values. The
experimental data are supported by theoretical ab initio calculations of the electron properties of
austenitic CrMn steels alloyed with carbon, nitrogen or carbon+nitrogen. Using the full-potentialfull-
electron-linearized-augmented-plane-wave (FLAPW) method, the total energy per primitive
crystal cell, the density of the electron states (DOS) and the distribution of the electron density over
the crystal lattice were calculated by means of the computational program WIEN-2k. The total
electron energy decreases due to alloying in the sequence of carbon→nitrogen→carbon+nitrogen,
which suggests a corresponding increase in the thermodynamic stability of the austenite. The
obtained results of the theoretical and experimental studies of the electron structure were used for
the development of super-high–strength stainless austenitic steels.
Hydrogen Sensing Characteristics of High Electron Mobility Transistor with a Catalytic Pd Metal
Authors: Lin Kun Wei
Published: March 2009

In this work, the comprehensive study of an interesting Pd/AlGaAs pseudomorphic high
electron mobility transistor (pHEMT) based hydrogen sensor is implemented. The theoretical
analysis and simulation are made by using a two-dimensional simulator Medici. In addition, a
practical device is fabricated successfully. Based on the variations of the catalytic metal work
function, the DC characteristics of experimental and simulated results are compared and studied.
Thermal Flow Simulation and Concave Type Slot Nozzle Design for Twin Roll Casting of Magnesium Alloy AZ31
Authors: Hu Xiao Dong , Ju Dong Ying , Zhao Hong Yang
Published: March 2009

Twin- roll casting of magnesium alloys is a rapidly solidifying process, which can directly
produce thin strips from molten metal. In this paper, based on a pilot vertical type twin-roll caster, 3D
models of twin-roll casting process were used for simulation of thermal flow and solidification on
depending of casting speed, molten pool level and pouring temperature. The effect of side dams on
thermal flow behavior was also considered. Based on the analyzed results, a proper concave slot
nozzle was designed to compensate temperature variation across the width of strip. Comparing with
parallel type slot nozzle, it can adjust temperature distribution along the roll width continuously by
adopting proper concave curves, which is more flexible than rectification boards delivery system.
Strips of magnesium alloy AZ31 were produced in the pilot caster with the concave slot nozzle. The
experiments show that surface quality of as cast strip was improved by using the new type of nozzle.
Nanotechnology: Better Materials for All Implants
Authors: Webster Thomas J.
Published: March 2009

Nanotechnology is being used to mimic structural components of our
tissues in synthetic materials intended for various implant applications. Recent studies
have highlighted that when compared to flat or micron rough surfaces, surfaces with
nanofeatures promote optimal initial protein interactions necessary to mediate cell
adhesion and subsequent tissue regrowth. This has been demonstrated for a wide
range of implant chemistries (from ceramics to metals to polymers) and for a wide
range of tissues (including bone, vascular, cartilage, bladder, and the central and
peripheral nervous system). Importantly, these results have been seen at the in vitro
and in vivo level. This short review paper will cover some of the more significant
advancements in creating better implants through nanotechnology efforts.
Cellular Activity and Biomaterial's Surface Topography
Authors: Nebe Barbara , Luethen Frank , Lange Regina , Beck Ulrich
Published: March 2009

The contact of a cell on the biomaterial’s surface is mediated by its adhesion
components. The topography of titanium surfaces influences these adhesion components of
osteoblasts, e.g. the integrins, the adapter proteins and the actin cytoskeleton.
In our current experiments we were interested in why osteoblasts were strongly aligned to the
grooves of a structured pure titanium surface (grade 2). The titanium was characterized by EIS to
get insights in the electro-chemically active surface. We used MG-63 human bone cells, cultured in
DMEM with 10% FCS at 37°C. For protein adsorption the titanium discs were incubated for 24h
with complete medium containing soluble fibronectin at 37°C. Interestingly, only in the grooves
cells adhered and were aligned and this is not dependent on the gravitation. The cell adhesion seems
to depend on the protein adsorption of fibronectin which we could find to be adsorbed exclusively
in the valleys. We speculate that there are local differences in electro-chemical characteristics of
this structured titanium surface.
Plasma and Electrospray Deposition to Improve the Biocompatibility of Stents
Authors: Tatoulian Michael , Gallino Enrico , Jafari R. , Arefi-Khonsari Farzaneh , Tatoulian L. , Borra Jean Pascal , Lewis François , Mantovani Diego
Published: March 2009

Metallic Intravascular stents are medical devices used to scaffold a biological lumen,
mostly diseased arteries, after balloon angioplasty. They are commonly made of 316L stainless steel or
Nitinol, two alloys containing Nickel, an element classified as potentially toxic and carcinogenic. Although
they are largely implanted, the long-term safety of such metallic elements is still controversial, since the
corrosion processes may lead to the release of several metallic ions. In order to avoid the metallic ion release
in the body and to improve the biocompatibility of metallic stents with their biological environments,
polymer coatings have been deposited by two different technologies, i.e. plasma surface modifications and
Electrospraying. The role of the polymer coating is then to encapsulate the stainless steel device, and to
favour the chemical grafting of Phosphorylcholine, a molecule known for its hemocompatible properties.1
In this talk, the state of the art on low pressure and atmospheric pressure plasmas for deposition of
organic coatings will be given and we will present the advantages and drawbacks of each process. Then, we
will present an original technology that combine a Dielectric Barrier Discharge and an electrospraying
system to deposit well-defined Polyacrylic acid and Polyallylamine films. The advantage of such system is
the possibility to limit the extent of the monomer fragmentation and to give rise to rapid deposition of a
highly functionalised plasma polymer layer, and also the possibility to cover three dimensional objects, such
as stents. Thus, the theory of EHDA technology will be explained: special attention has been paid to define
the Electrospray parameters (Voltage, flow of precursor, nozzle-substrate distance…) which control the size
distribution of the charged droplets and as a consequence, the structure of the film coating. The film coatings
have been analysed with XPS and by ATR. Moreover, special attention will be paid on the stability of the
coating which is related to both spraying conditions as well as to the preliminary plasma treatment. The
potentiality and the features of the EHDA process will be then presented.
An Injectable Biomaterial for Bone Repair
Authors: Jarry Claire , Shive Matthew , Chenite Abdellatif
Published: March 2009

The primary purpose of this study was to characterize the main features of a BCP-loaded
chitosan-GP composite. The two-syringe design improves the storage conditions, facilitates the
sterilization procedure and provides an easy-to-use injectable biomaterial, ensuring reproducible
properties with minimal manipulation. Rheological measurements confirm that the chitosan-
GP/BCP composite retains the thermosensitive properties already described for chitosan-GP
hydrogels. At 37°C, the system gels within 10 minutes and reaches sufficient consistency after 30
minutes to prevent the mineral granules from migration into the surrounding tissues in vivo. The
compressive force needed for the injection of chitosan-GP/BCP before gelation is approximately 6.6
N, only about 6 times that required for water and much lower than the average force that the
majority of adults can exert. Morphology was investigated by environmental scanning electron
microscopy (ESEM), which revealed 3-D dispersion of BCP granules embedded in chitosan-GP
hydrogel. This open, porous structure affords complete access for body fluids and cells to each
mineral granule immediately following implantation. The design using disposable syringes
equipped with 16G hypodermic needles described here allows easy in vivo delivery of a fully
injectable biomaterial containing porous scaffold that naturally enhances the osteogenic activity
recognized for both chitosan and BCP.
Evaluating the In Vitro and In Vivo Efficacy of Nano-Dimensional Polymeric Scaffolds for Bladder Tissue Replacement Applications
Authors: Haberstroh Karen M. , Pattison Megan A. , Kaefer Martin , Webster Thomas J.
Published: March 2009

Superficial bladder cancer is often treated by removing the cancerous portion of the
bladder wall combined with immuno-chemotherapy; in more extreme cases, it is often necessary to
remove the entire bladder wall. This diagnosis brings an obvious need for bladder tissue replacement
designs with a high degree of efficacy. Since bladder cells are accustomed to interacting with
extracellular matrix proteins having dimensions on the nanometer scale, this study aimed to design
the next generation of tissue-engineered bladder replacement constructs with nanometer (less than
100 nm) surface features. For this purpose, porous and biodegradable PLGA and PU scaffolds were
treated with various concentrations of NaOH or HNO3, respectively, for various periods of time to
create nanometer surface roughness. Resulting surface properties were characterized using SEM (to
visualize scaffold properties) and BET. Cell experiments conducted on these polymeric scaffolds
provided evidence of enhanced bladder smooth muscle cell attachment, growth, and elastin/collagen
production (critical extracellular matrix proteins in the bladder tissue regeneration process) as surface
feature dimensions were reduced into the nanometer regime. In vivo augmentation surgeries with
nano-structured PLGA and PU patches will provide further information regarding total bladder
capacity, anastomotic integrity, burst pressure, epithelialization, muscular ingrowth, and
neovascularization. In vitro and in vivo proof of material usefulness and technique would provide
urologists with a readily accessible graft for bladder tissue replacement applications.
The Remineralizing Effect of Carbonate-Hydroxyapatite Nanocrystals on Dentine
Authors: Rimondini Lia , Palazzo Barbara , Iafisco Michele , Canegallo Lorenza , Demarosi Federica , Merlo Michela , Roveri Norberto
Published: March 2009

The use of specific remineralizing agents in toothpastes may help to prevent caries and
treat dentinal sensitivity. In this study, applied nanotechnologies were used to develop a filler for
toothpastes with remineralizing properties.
Carbonate hydroxyapatite nanocrystals, with size, morphology, chemical composition and
crystallinity comparable with that of dentine, were synthesized in mild condition.
The remineralizing effect was studied with a scanning electron microscopy putting materials onto
the slices of dentine previously demineralized with ortophosphoric acid. The application of the
materials showed the progressive closure of the tubular openings of the dentine with plugs within
10 minutes and a regeneration of a surface mineral layer within 6 hours. This rates of
remineralization seems to be compatible with the development of toothpastes with remineralizing
effect.