bluuebunny/crossref_metadata_2025 huggingface dataset:
Influence of Residual Stress Redistribution on Fatigue Crack Growth and Damage Tolerant Design
Authors: Edwards Lyndon
Published: March 2009

The safe operation of many structures and components is ensured through the operation
of damage tolerant design and evaluation. Substantial residual stresses can exist in many systems
and it is important that these are incorporated in damage tolerance calculations of fatigue crack
growth. Recent improvements in non-destructive measurement techniques and in the application of
weight or Green’s functions methods of including residual stress fields into stress intensity factor
(SIF) calculations have enabled predictions of the effects of residual stresses on fatigue crack
propagation to be made more readily. Two examples from the aerospace industry, structures
containing (i) cold expanded holes and (ii) fusion welds are used to show that presently, although
final crack growth lives can be accurately predicted, the details of crack growth are not well
represented with initial growth typically being underestimated and later growth being over
estimated. It is shown that this is most likely to be due to residual stress redistribution. and that this
must be built into fatigue life prediction models if accurate damage tolerance based procedures are
to be developed for components and systems containing substantial residual stresses.
Determination of Real Space Residual Stress Distributions σij(z) of Surface Treated Materials with Diffraction Methods Part II: Energy Dispersive Approach
Authors: Denks Ingwer A. , Klaus Manuela , Genzel Christoph
Published: March 2009

The detection of near surface residual stress gradients in real space requires high depth
resolution for any orientation of the diffraction vector with respect to the sample co-ordinate system.
In order to meet this demand, the slits are no longer being fixed in the laboratory co-ordinate system
as in strain scanning experiments but directly coupled with the sample. Hence, the gauge volume
orientation within the sample remains constant and allows performing depth-resolved sin2ψ
measurements in real space. The method’s accuracy is determined by the gauge volume definition,
which is investigated in detail. Apart from the evaluation of the σ(τ) versus σ(z) relation, which is of
fundamental interest in X-ray residual stress gradient analysis, the method will be shown to have a
unique applicability in rather delicate sample geometries such as multilayer systems.
Residual Stresses in Welded Joints after Different Mechanical Surface Treatments
Authors: Nitschke-Pagel Thomas , Eslami-Chalandar Hamdollah
Published: March 2009

Investigations on welded joints of a low strength steel and of an age-hardened aluminium-
alloy have been performed to compare the effects of different post-weld treatment methods.
The experimental results show, that the methods which are working with help of ultrasonic activation
lead to a higher depth of penetration of the compressive residual stresses as shot peening does.
The cold worked surface area is deeper and the hardening effect can be found in deeper layers. Furthermore
the shape of the weld toe is changed strongly due to the cold working of the surface with
the consequence of a change of the weld toe geometry. Anyway the fatigue strength improvement is
comparable to that which is generated by shot peening (steel) or less than after shot peening (aluminium).
The reason is, that the shape of the treated weld toe profile must not be necessarily
smoother due to the ultrasonic hammer peening. Depending on the treatment parameters also sharp
defects can be produced at the boarder of the treated zone which may compensate the beneficial effect
of the compressive residual stresses.
Diffraction Post-Processor for Polycrystalline Plasticity Modelling
Authors: Dini Daniele , Korsunsky Alexander M. , Dunne Fionn P.E.
Published: March 2009

Microscopic and macroscopic deformation of a polycrystal due to an applied load can be
modelled using crystal plasticity implemented within the Finite Element (FE) framework. However,
while macroscopic predictions can readily be validated against conventional monotonic and cyclic
stress-strain curves, verification at the microscopic level is harder to achieve, since it involves
calibrating the predictions for stresses and strains in individual grains, or in grains grouped by
certain criteria (e.g., orientation).
In this paper an elasto-plastic polycrystal finite element model is introduced, and its calibration is
performed at a mesoscopic level via comparison with neutron diffraction data obtained
experimentally. Time-of-flight (TOF) neutron diffraction experiments carried out on ENGIN-X
instrument at ISIS involved in situ loading of samples of C263 nickel-based superalloy. In order to
compare the numerical predictions of the FE model with these experimental data, the corresponding
mesoscale average elastic strains must be extracted from the results of the simulation by employing
a ‘diffraction post-processor’. This provides a much improved technique for the calibration of FE
formulation and enhances the confidence in the model. The FE diffraction post-processing
procedures are discussed in detail, and comparison between the model predictions and experimental
data are presented.
Letterbox Type Repair Weld Finite Element Simulation and Residual Stress Prediction
Authors: Keppas L.K. , Katsareas Dimitrios Elias , Wimpory Robert C. , Anifantis N.K. , Youtsos Anastasius
Published: March 2009

Finite element prediction of residual stresses in a 3-bead letterbox-type repair weld is
investigated in the present study. The repair is performed on a 2¼CrMo low alloy ferritic steel
plate, containing a machined central groove where three weld beads are deposited using AL
CROMO S 225 2¼CrMo electrodes. The proposed simulation procedure, which is based on
decoupled thermal and mechanical analyses and the “birth and death of elements” technique, is
evaluated through comparison of predicted stresses with neutron diffraction testing data. Parametric
studies include modelling aspects such as 2-D plane strain versus 3-D analysis, re-melting of weld
material during sequential bead deposition, melting of base plate near the fusion line and annealing.
It is concluded that numerical results come, in general, in satisfied agreement with the experimental
data.
Laser Photoacoustic Microscopy of Mechanical Stresses in Modern Ceramics and Metals
Authors: Muratikov K.L. , Glazov A.L.
Published: March 2009

The photoacoustic piezoelectric images of Vickers indented silicon nitride, Al2O3-SiCTiC
composite ceramic, nanonickel and nanocopper in unloaded and loaded states are presented. It
is demonstrated the influence of mechanical stresses on the photoacoustic images of Vickers
indented areas both for ceramics and metals. For Al2O3-SiC-TiC composite ceramic it is also shown
that an increase of annealing time is accompanied by the decrease in the photoacoustic response
from the radial crack tips. The obtained photoacoustic experimental results are explained within the
framework of the model for the photoacoustic effect in stressed solids proposed by us earlier.
Experimental Study of the Influence of a Trailing Heat Sink on the Welding Residual Stress Distribution
Authors: van der Aa E.M. , Hermans M.J.M. , Richardson I.M. , van der Pers N.M. , Delhez Rob
Published: March 2009

It has been shown that the introduction of a trailing heat sink following a welding heat
source at a short distance can reduce or even eliminate the buckling deformation of welded thin
plate structures. To increase the insight into the stress development during welding with a trailing
heat sink, residual stress measurements were carried out by means of laboratory X-ray and
synchrotron X-ray diffraction techniques. Both the laboratory X-ray and the synchrotron X-ray
experiments show a difference between the residual stress distributions for the cooled and the
uncooled samples. The longitudinal stresses show a reduction in the compressive stress level
towards the plate edges, to a level below the critical buckling stress. The transverse stresses are
drastically reduced when the active cooling is applied.
Post-Weld Heat Treatment Stress Relaxation in Zircaloy 4 Plasma Welds
Authors: Santisteban Javier R. , Fernández L. , Corso H. , Martínez R.L. , Boccanera L. , Edwards Lyndon , James Jonathan A. , Turski Mark
Published: March 2009

We have studied the effect of a post-weld heat treatment on plasma arc welds on Zircaloy
4 plates. The samples consist of two 100 mm long, 50 mm wide, and 6.25 mm thick plates, welded
along the rolling (longitudinal) direction. The heat-treatment consisted of a steady increase in
temperature from room temperature to 450oC over a period of 4.5 hours; followed by cooling with
an equivalent cooling rate. Residual strains and stresses along the longitudinal, transverse and
normal directions on an as-welded and a heat-treated specimen were measured by neutron
diffraction on the ENGIN-X beamline at the Isis Facility, Rutherford Laboratory, UK. Peak tensile
stresses of (105±25) MPa were found in the as-welded specimen, which were reduced to (70±20)
MPa after the heat-treatment. Thermal compressive stresses of (-80±20) MPa were found along the
normal direction, which were not affected by the heat treatment. The use of a full-pattern Rietveld
refinement for the determination of bulk strains in Zircaloy specimens is also discussed.
Stability of Residual Stresses of Deep Rolled Sintered Iron at Quasistatic and Cyclic Loading
Authors: Merkel Jens , Schulze Volker , Wanner Alexander , Vöhringer Otmar
Published: March 2009

In the work presented here the residual stress states of sintered iron (ASC 100.29) were
studied after mechanical surface treatments. This included the investigation of the stability of compressive
residual stresses of deep rolled sintered iron at different angles relative to the rolling
direction at quasistatic and cyclic bending loading. An increase of the compressive residual stress in
the transversal deep rolling direction at fatigue loading was found and will be discussed in this
presentation.
Numerical Study of the Influence of Dislocation Microstructure on Metallic Materials Mechanical Behaviour
Authors: Gloaguen D. , Fajoui Jamal , Courant Bruno , Guillén Ronald
Published: March 2009

A two-level homogenisation approach is applied to the micro-mechanical modelling of
the elasto-plasticity of polycrystalline materials during various strain-path changes. The model is
tested by simulating the development of intragranular strains during different complex loads.
Mechanical tests measurements are used as a reference in order to validate the model. The
anisotropy of plastic deformation in relation to the evolution of the dislocation structure is analysed.
The results demonstrate the relevance of this approach for FCC polycrystals.
Deep Hole Drill Residual Stress Measurement Technique Experimental Validation
Authors: Mabe W.R. , Koller W.J. , Holloway A.M. , Stukenborg P.R.
Published: March 2009

This paper presents the results of an experimental validation of the deep hole drill residual stress
measurement method. A validation test specimen was fabricated and plastically loaded to impose a
permanent residual stress field within the specimen. The validation test specimen was designed to
provide a variety of stress profiles as a function of location within the specimen. A finite element
analysis of the validation test specimen was performed in order to provide a reference solution for
comparison to the deep hole drill experimental results. Results from experimental testing of the
validation test specimen agree well with the finite element analysis reference solution, thereby
providing further validation of the deep hole drill method to measure residual stresses.
Influence of Work Material Properties on Residual Stresses and Work Hardening Induced by Machining
Authors: Outeiro J.C. , Dias A. Morão
Published: March 2009

Machining residual stresses are considered as part of surface integrity and a consequence
of the machining process. Theses stresses are closely correlated with the corresponding process
parameters, including the work material properties. As it is well known, not only the mechanical but
also the physical properties of the work materials have great influence on machining residual stress.
This was demonstrated in the present work through studying the residual stress and work hardening
induced by the turning of AISI 316L and AISI 1045 steels. The residual stresses were determined at
the workpiece surface and in-depth using the X-ray diffraction technique. To understand the
influence of the work material properties on the residual stress and work hardening distributions, the
mechanical and thermal phenomena occurring during the cutting process were studied, using a t
developed experimental procedure. The experimental setup included a piezoelectric dynamometer to
determine the cutting forces, and thermal imaging equipment developed to assess the temperature
distribution in the deformation zone in turning. The results showed that the cutting forces and
temperatures in the machining of 316L steel are much higher than those in the machining of 1045
steel. Thus, machining 316L steel, when compared to 1045 steel, results in higher superficial
residual stresses and stronger in-depth residual stress gradients, higher superficial work-hardening
and greater thickness of the work hardened layer.
Measurement of Residual Stress in an A533B Ferritic Steel Plate Containing a Repair Weld
Authors: Ficquet X. , Truman Christopher E. , Smith David John
Published: March 2009

The paper presents the results of residual stress measurements on a ferritic steel plate
containing a repair weld. The repair was considered representative of that found in the secondary
circuit piping in power plant. The paper primarily uses the deep hole drilling (DHD) technique, but
compares results found by this technique with those obtained using neutron diffraction. Both sets of
measurements confirmed that highly tensile residual stresses exist in the repair weld. The two
measurement techniques produced results that were in acceptable agreement, but the neutron
diffraction results were consistently higher than the deep hole drilling results. It was thought this
was due to the use of a constant stress-free lattice parameter d0 .
Layer Growing/Removing Method for Determination of Residual Stresses in Thin Orthotropic Inhomogeneous Discs
Authors: Kõo Jakub , Valgur Jaak
Published: March 2009

An algorithm of the layer growing/removing method for computing of the residual
stresses in thin orthotropic inhomogeneous circular disc is presented. The stresses are calculated
from strain measurements on the free stationary contour or on the lateral surface, or from X-ray diffraction
measurements on the disc’s moving contour.
The suggested algorithm is programmed for PC. Two illustrative examples are presented.
Residual Strain Measurement of C/C-SiC Tubes at High Temperature
Authors: Wimpory Robert C. , Ohms Carsten , Horňak Peter , Neov Dimitar , Youtsos Anastasius
Published: March 2009

As part of the European project “high and ultrahigh temperature heat exchangers”
(HITHEX) the prediction and experimental assessment of the lifetime behaviour, characterisation
and qualification of particular CMC materials, including carbon fibre reinforced carbonsiliconcarbides
(C/C-SiC), has been executed. Part of the programme of the HITHEX project was
the measurement of the strain development within the C/C-SiC tubular specimens from room to
high temperature, the results of which are presented here. Residual strains have been determined in
several specimens by neutron diffraction at the High Flux Reactor (HFR) of the Joint Research
Centre in Petten, The Netherlands. At the HFR two facilities are available for residual strain
investigations. Both instruments were utilised in the investigations. The first facility at beam tube
HB5, the combined stress and powder diffractometer, employs a constant neutron wavelength of
0.257 nm, and the second facility at HB4, the Large Component Neutron diffraction facility,
LCNDF, has a flexible wavelength. The installation of a vacuum furnace has enabled the residual
strain measurement of specimens at high temperature on HB4. The furnace had to fulfil three main
criteria for the investigation of these specimens; high-temperature, good neutron penetration and
negligible oxidation of the specimens. The ceramic specimens, which have outer and inner
diameters of 50 and 40 mm, respectively, and a length of 100 mm have been measured to
temperatures of up to 1450°C. Measurements were carried out in two directions on the SiC phase of
several specimens, i.e. in the radial and tangential (hoop) directions. The implications of these
results with respect to the structural integrity assessment of these components at high temperatures
are discussed.
Geometry Effects when Controlling Residual Stresses in Friction Stir Welds by Mechanical Tensioning
Authors: Richards David G. , Prangnell Phil B. , Withers Philip J. , Williams Stewart W. , Wescott Andrew , Oliver E.C.
Published: March 2009

Finite element modelling has proved to be an effective tool for the investigation of trends
effected by changing welding conditions. This is especially important in mechanical tensioning of
friction stir welds because of the large number of parameters involved. In this paper, an FE model is
used to examine the effectiveness of the mechanical tensioning technique for controlling residual
stresses in FSWs by the investigation of trends caused by changes to the welding parameters.
Comparisons between different geometries, traverse speeds, and welding off-axis angle all produced
consistent results, and showed that the peak stresses are most strongly influenced by both the local
tensioning and heat input, and not by the more global welding conditions. The results also showed a
progressive decrease in the residual stresses for increasing tensioning levels and, although affected by the
heat input, a relatively low sensitivity to the welding variables. At tensioning levels greater than ~50% of
the room temperature yield stress, tensile stresses were replaced by compressive residual stresses within
the weld.
Stresses Analysis on Coarse Grain Zn Film during Tensile Loading
Authors: Huang Wen Jun , Ji Vincent , Seiler Wilfrid
Published: March 2009

The advance of the XRD technique allows us to reach the properties of each coarse grain.
This paper has demonstrated a new method to determine stress in a single crystal for multicrystal
material and this new method could be specially applied for any symmetric crystalline systems. The
strain tensor ε is determined by the change of the metric tensor G before the initial state and after
the deformed state in the crystal reference system. Then stress tensor at grain scale is calculated by
the Hooks law. The stress evaluations are carried out in coarse grains of a thin galvanized coating
on a steel substrate during tensile loading. This study allows us to link the microstructure evolution
to the elastic heterogeneity at grain scale or between the grains.
Scratch Test of TiCN Thin Films with Different Preferred Orientation
Authors: Goto Hiroshi , Gotoh Masahide , Ejiri Shouichi , Horimoto Yoshiaki , Hirose Yukio
Published: March 2009

The purpose of this study is to examine the effect of crystallite preferred orientation on the
mechanical strength of TiCN thin films in highly compressive residual stress. TiCN thin films were
deposited by PVD on JIS-SKH55 (AISI M35) steel. The applied substrate bias voltages were set for
–50, -80, -100, -120 and –150V. Subsequently, residual stress and crystalline preferred orientation of
these specimens were investigated by X-ray diffraction methodology. The crystalline preferred
orientation in thin films was evaluated by the ODF calculated from pole figures. On the other hand,
dynamic hardness test (DH) and scratch test were executed to evaluate the mechanical strength of thin
films.
In our study, it was observed that negative bias voltages had an effect on the preferred orientation. The
orientation density at –120V was the highest of all specimens. In addition, the value of scratch section
area at –120V was the largest of all specimens. As a conclusion, the relation between the scratch area
and the negative bias voltages corresponded to the relation between the preferred orientation and the
bias voltages.
Specific Corrections Associated to Linear CCD Detectors Used in X-Ray Diffraction
Authors: Ferreira C. , François Manuel , Guillén Ronald
Published: March 2009

For a few years, new kinds of setups for residual stress analysis by X-ray diffraction have
been commercialised by manufacturers with two linear Position Sensitive Scintillation Detectors
(PSSD) including Charge-Coupled Device (CCD) sensors. Although these equipments allow an
important reduction of acquisition time, some questions subsist on their measurement reliability,
especially on the raw profile corrections and on the associated statistical uncertainty. One of them
concerns the required gain correction because of the weak spatial homogeneity of these detectors. In
fact, a bad knowledge of sensor noise does not permit a good correction of the raw patterns which
can significantly affect the results of stress measurements. In this study, an original statistical
analysis is proposed to visualize and analyse the various kinds of intrinsic noise of PSSD detectors,
and especially the most important one: the dark noise. Based on the results of this investigation, a
method for gain correction is then proposed. The method, easy to apply, permits a better correction
of the sensors defects without increasing acquisition time. This analysis also allows a better
understanding of the sensors behaviour and thus an optimisation of the acquisition.
Measuring and Predicting the Effects of Residual Stresses on Crack Propagation
Authors: Shterenlikht A. , Stefanescu Danut , Fox Matthew E. , Taylor Kerry , da Fonseca Joao Quinta , Sherry Andrew H. , Withers Philip J.
Published: March 2009

This article presents the first part of a study on the interaction between residual stresses and crack
driving force. Blunt notched CT specimens were pre-strained to introduce residual stresses at the
notch, where a crack is subsequently introduced. FE modelling is used to model the specimen preload
and pre-cracking. Modelling predictions are validated by two different methods. The total
predicted surface residual strains are compared to image correlation measurements. The predicted
residual strains were measured using neutron diffraction, both before and after fatigue cracking. The
residual strain profiles show good agreement with the 3D FE model in the far field but the peak strains
measured near the notch are smaller those predicted. This is a result of the low spatial resolution of
the technique.
Dependence Between Aging Treatments and Residual Stresses on Composite Laminate
Authors: Sicot Olivier , Gong X.L. , Gong Xiao Jing , Cherouat Abel , Lu Jian
Published: March 2009

The objective of this paper is to study the influence of residual stresses due to fabrication
conditions on the thermomechanical behavior of carbon/epoxy laminate structures (cross ply).
These studied laminates have undergone various cycles of thermal aging. The addition of a
post-cure cycle after the end of the initial cycle makes it possible to reduce the residual
stresses level. The incremental hole-drilling method is used to measure the residual strain in
the laminates. These measured strains and the numerical calibration coefficients obtained by
the finite element method allow to calculating the residual stress distribution in composite
depth. The obtained results show that heat treatments of composite structures do not lead to an
important reduction the initial residual stress due the fabrication conditions.
Residual and Internal Stress States in Duplex Steel with TWIP Effect
Authors: Shiekhelsouk M.N. , Favier Véronique , Inal Karim , Allain Sebastien , Bouaziz Olivier , Cherkaoui M.
Published: March 2009

A new variety of duplex steels with superior mechanical properties has been studied.
They exhibit a very interesting combination of strength (tensile strength of 680 MPa) and ductility
values (more than 45% total elongation) due to the competition between different plasticity
mechanisms. These steels contain two phases: austenite and ferrite and are characterized by low
stacking fault energy at room temperature. In this work, four duplex steels with different chemical
composition and phase volume fraction are studied. Residual and internal stresses in each phase
were determined using the classical X-ray diffraction sin²ψ method. In the as-received state, both
longitudinal and transverse residual stresses are in compression (until -350 MPa) for the ferrite and
in tension (until +410 MPa) for the austenite. However, residual stresses in the austenitic phase
decrease when its volume fraction increases. Moreover, internal stress distribution in one alloy was
determined by X-ray diffraction during an in situ tensile test. The austenitic phase stress along the
loading direction is higher than the macroscopic applied one, which is higher than the ferritic stress
state, verifying a mixture rule and consistent with the initial residual stresses. For an applied
macroscopic strain of about 1%, the austenite phase is subjected to a stress of about 600 MPa
whereas the stress in the ferritic phase is about 300 MPa. It was also observed that as macroscopic
strain increases, stress difference between the austenite and the ferrite decreases.
Quantitative Estimation of the Second Order Plastic Incompatibility Stresses in Textured Duplex Steel
Authors: Wroński Sebastian , Baczmanski Andrzej , Wierzbanowski Krzysztof , Braham Chedly , Dakhlaoui Rim , Oliver E.C.
Published: March 2009

A new method for determining the parameters characterising elastoplastic deformation of
two-phase material is proposed. The method is based on the results of neutron diffraction, which are
analysed using the self-consistent rate-independent model of elastoplastic deformation. The neutron
diffraction method (time-of-flight technique) was applied and the self-consistent model was used to
predict the second order stresses in austeno-ferritic duplex steel. Calculations based on the model
were successfully compared with experimental results for both phases of the duplex steel.
Fatigue Degradation and Martensitic Transformation of Austenitic Stainless Steel AlSi 321: New Results and Prospects
Authors: Taran Yu. V. , Schreiber Jürgen , Daymond Mark R. , Oliver E.C.
Published: March 2009

On ECRS-6 [1], we have presented first results of the researches of fatigue degradation
and martensitic transformation of austenitic stainless steel AISI 321 by neutron diffraction stress
analysis. A series of samples preliminary ex-situ cyclically fatigued at the frequency of 5 and 0.5 Hz
was in-situ tested on the stress rig of the ENGIN instrument. In the high cycle fatigued (HCF)
samples, the applied stress-elastic strain responses of austenite and martensite phases were find out
to be strongly different as compared to the low cycle fatigued (LCF) samples, in which they are
close. Moreover, the martensite Poisson ratio in the HCF-samples is almost twice to that of
observed 0.28-0.30 in austenite and in both phases of the LCF-samples. With the purpose to search
the reason of such unusual behavior of the martensite phase, one of the HCF-samples has been
anew in-situ tested on the stress rig of the ENGIN-X in: 1) a LCF-mode at the frequency of 0.1 Hz
to increase the fatigue level, and 2) a quasistatic mode to measure the applied stress-elastic strain
responses of both phases. Also, two of the LCF-samples have been subjected to the ex-situ
secondary HCF-testing at the frequency of 5 Hz and again in-situ measured on the ENGIN-X stress
rig. Results of the mechanical characterization of phases in the twice fatigued austenitic stainless
steel are presented and discussed.
Evolution of Microstrains at Cyclic Incremental Deformation of Steel 42CrMo4
Authors: Meyer Lothar W. , Kuprin C. , Fritsche Gudrun , Hahn F.
Published: March 2009

X-ray diffraction line profiles of a ferritic-pearlitic steel at different stages of
monotonic and cyclic incremental strain paths were recorded and peak broadening was
regarded. Evaluation of integral peak widths shows, that the distortion of structure is strongly
dependent on the deformation path. The results for peak broadening at different deformation
states correlate with flow stress behaviour and can be explained with certain dislocation
arrangements.
Formation and Interpretation of Micro Residual Stresses in Cold Deformed Brass Alloys
Authors: Reetz Bjoern , Reimers Walter
Published: March 2009

The brass alloys CuZn10 and CuZn37 were cold deformed by uniaxial compression in
steps of 5 % res. 10 % to 20 %.
Using X-ray synchrotron radiation d versus sin2ψ-distributions were measured. All diagrams
showed strong non-linearities which were furthermore different for different hkl. The amplitudes of
the oscillations increase with increasing deformation but come to a saturation, for CuZn37 at
approximately 10 % compression, for instance.
The development of the hkl-dependent residual stresses and the oscillations could be related to
different microstructures induced by cold deformation. The Voigt-model suits well to describe the
oscillations in d-sin2ψ curves associated with the hot extrusion process which was used for the
fabrication of the samples.
Moreover, it is shown that additional information obtained from TEM and X-ray line profile
analysis is necessary to reproduce the experimental oscillations of d versus sin2ψ-distributions
measured in cold deformed samples.
X-Ray Stress Estimation of Carbide in Spheroidized JIS SK5 Steel
Authors: Che Lei , Gotoh Masahide , Horimoto Yoshiaki , Hirose Yukio
Published: March 2009

The low volume fraction of carbide phase in carbon steel determines that it is difficult to
estimate the stress state in it by diffraction method. In the present study, different from the studies
before, we improve the technique of surface treatment on specimen and have successfully finished the
stress estimations of carbide phase in carbon steels by X-ray diffraction method under normal
conditions. Moreover, we investigate the affection of spherical cementite particle size on the residual
stress distribution in both phases during the plastic deformed steels. We observed that the steels with
small-sized cementite particles showed higher stress states than the steels with relatively large-sized
cementite particles.
Dependence of Oxidation Behavior and Residual Stresses in Oxide Layers on Armco Iron Substrate Surface Condition
Authors: Juricic Claudia , Pinto Haroldo , Wroblewski Thomas , Pyzalla Anke
Published: March 2009

Mass gain during oxidation, texture and residual stresses in oxide layers on
polycrystalline Armco iron substrates with different surface conditions are investigated using
thermogravimetry microscopy and synchrotron X-rays. The mass gain during oxidation in all
samples follows a parabolic law. The parabolic oxidation constant increases with increasing
roughness of a mechanically ground respectively polished oxide layer. Electrolytic polishing (grain
surface etching) reduces while grain boundary etching increases the parabolic oxidation constant
compared to the mechanically polished sample. All oxide layers show columnar growth of the
magnetite and a moderate fiber texture. The magnetite contains compressive residual stresses.
Under the conditions chosen for the oxidation treatment the magnitude of these compressive
residual stresses does not depend on the substrate surface condition.
Residual Stress Analysis in Reed Pipe Brass Tongues of Historic Organs
Authors: Manescu Adrian , Giuliani Alessandra , Fiori Fabrizio , Baretzky B.
Published: March 2009

True Baroque organ music can only come back to life in the 21st century by developing Cu-based
alloys and implementing them in the organ reed pipes. Reed pipes contain a vibrating part, the brass
tongue that crucially influences its sound. Energy dispersive synchrotron X-ray diffraction has been
performed in order to investigate residual stresses in the tongues. The in depth analysis gives us an
important indication on the processes the tongues were submitted to during their manufacturing:
hammering, annealing, filing to the neat thickness, curving of the tongues. A biaxial stress state in
the organ tongues was considered. The residual stress values and behaviour were correlated to the
manufacturing processes.
Investigation on the Predictive Model for Burr in Laser Cutting Titanium Alloy
Authors: Chien Wen T. , Hung W.C.
Published: March 2009

The purpose of this study is to develop two predictive models for burr height in cutting
titanium alloy plates by using Nd:YAG laser. Firstly, Taguchi method has been used to arrange the
experimental scheme and analyze the results via analysis of mean . The important laser cutting
parameters affecting burr height can be found. It shows that the pressure of assistant gas, the
focusing position and the pulsed frequency are the most important cutting parameters in order. Then
they have been chosen as the input variables for response surface methodology and used to
construct a mathematical equation for predicting burr height. Secondly, the laser cutting parameters
and experimental results obtained from conducting the schematic arrangement using Taguchi
method and response surface methodology have been treated as training patterns and recalling
patterns for the back-propagation neural network. As a result, a predictive model for burr height
prediction in laser cutting titanium alloy has been established. To verify the accuracy of above two
prediction models, there are 9 sets of experiment have been performed. It shows that the average
error for predicting burr height by the mathematical equation derived from response surface
methodology is 5.52% and by the predictive model established by back-propagation neural network
is 4.51%, respectively. Obviously, both predictive models are good enough for the relational
research and practical applications. It can be concluded that the procedure used in this research and
the obtaining predictive models can be used practically in correlate industry.
CVD Diamond Coatings for Machining
Authors: Moulin D. , Raymond O. , Chevrier P. , Lipiński Paul , Barre Thierry
Published: March 2009

Machining of modern materials requires high performance tools. More than 60% of metal cutting tools used are coated to limit abrasive wear. As the harder material known to man, diamond and consequently Chemical Vapour Deposited (CVD) diamond coatings allow to increase performances of tungsten carbide tools, i.e. tool life, machined surface quality, and to decrease costs. However, CVD diamond coated tools quality is very dependent on the surface preparation as much as the fabrication process parameters. This paper aims to discuss the influence of pretreatments before deposition, and thermal stresses induced by the cooling operation. Diamond deposition process is described emphasizing the role of every step and its function. Some numerical simulations of the residual stresses at the interface are presented, enlightening that tool geometry is an important factor while using a coating, and that tools must be designed for the diamond coating.
Solution Growth of SiC Crystal with High Growth Rate Using Accelerated Crucible Rotation Technique
Authors: Kusunoki Kazuhiko , Kamei Kazuhito , Okada Nobuhiro , Yashiro Nobuyoshi , Yauchi Akihiro , Ujihara Toru , Nakajima Kazuo
Published: March 2009

We performed solution growth of SiC single crystals from Si-Ti-C ternary solution using
the accelerated crucible rotation technique (ACRT). It was confirmed that the growth rate exceeding
200 μm/hr was achievable by several ACRT conditions. This high growth rate might be due to the
enhancement of the carbon transport from the graphite crucible to the growth interface using the
ACRT. Moreover, the incorporation of inclusions of the Si-Ti solvent in the grown crystal was
significantly suppressed by using the ACRT. It was thought that the intensive convection near the
growth interface resulted in not only the marked increase of SiC growth rate but also the superior
homogeneity in the surface morphology. It was concluded that faster stable growth can be
accomplished in the SiC solution growth using the ACRT.
Techniques for Minimizing the Basal Plane Dislocation Density in SiC Epilayers to Reduce Vf Drift in SiC Bipolar Power Devices
Authors: Sumakeris Joseph J. , Bergman Peder , Das Mrinal K. , Hallin Christer , Hull Brett A. , Janzén Erik , Lendenmann H. , O'Loughlin Michael  J. , Paisley Michael J. , Ha Seoyong , Skowronski Marek , Palmour John W. , Carter Jr. Calvin H.
Published: March 2009

Forward voltage instability, or Vf drift, has confounded high voltage SiC device makers
for the last several years. The SiC community has recognized that the root cause of Vf drift in
bipolar SiC devices is the expansion of basal plane dislocations (BPDs) into Shockley Stacking
Faults (SFs) within device regions that experience conductivity modulation. In this presentation,
we detail relatively simple procedures that reduce the density of Vf drift inducing BPDs in epilayers
to <10 cm-2 and permit the fabrication of bipolar SiC devices with very good Vf stability. The first
low BPD technique employs a selective etch of the substrate prior to epilayer growth to create a
near on-axis surface where BPDs intersect the substrate surface. The second low BPD technique
employs lithographic and dry etch patterning of the substrate prior to epilayer growth. Both
processes impede the propagation of BPDs into epilayers by preferentially converting BPDs into
threading edge dislocations (TEDs) during the initial stages of epilayer growth. With these
techniques, we routinely achieve Vf stability yields of up to 90% in devices with active areas from
0.006 to 1 cm2, implying that the utility of the processes is not limited by device size.
Epitaxial Growth of 4H-SiC on 4º Off-Axis (0001) and (000-1) Substrates by Hot-Wall CVD
Authors: Wada Keiji , Kimoto Tsunenobu , Nishikawa Kimito , Matsunami Hiroyuki
Published: March 2009

4H-SiC layers have been homoepitaxially grown on 4°off-axis (0001) and (000-1) under
various conditions by horizontal hot-wall CVD. We have investigated surface morphology and
background doping concentration of the epi-layers on 4°off-axis substrates. Surface morphology
grown on the (0001) Si-face showed strong step bunching under C-rich conditions. On the other hand,
smooth surface morphology on the (000-1) C-face could be grown in the wide C/Si ratio range at
1600 °C. Site-competition behavior is clearly observed under low-pressure growth conditions on
4°off-axis (000-1) C-face, leading to a lowest doping concentration of 4.4x1014 cm-3.
Thick Epitaxial Layers on 4º Off-Oriented 4H-SiC Suited for PiN-Diodes with Blocking Voltages above 6.5 kV
Authors: Hecht Christian , Thomas Bernd , Bartsch Wolfgang
Published: March 2009

This work presents results on the growth of thick epitaxial layers on 4° off-oriented 4HSiC
in a commercially available hot-wall CVD system. Results on background doping level,
homogeneity of thickness and doping, and run-to-run reproducibility will be shown. Defect
structures we observed on 4° off-oriented substrates only are discussed. AFM measurements are
presented to show the degree of step-bunching. 6.5 kV PiN-diodes with an active device area of
5.7 mm2 were fabricated and electrically characterized. In spite of the surface defects and stepbunching,
up to 50% of the devices per wafer fulfilled our strict yield criteria even at 6.5 kV. Up to
the onset of avalanche, the devices exhibited extremely low leakage currents. These results turn the
cheaper 4° off-oriented substrates into a promising choice for producing higher volumes of highvoltage
SiC power devices at reasonable costs.
CVD Epitaxial Growth of 4H-SiC on Porous SiC Substrates
Authors: Shishkin Y. , Ke Yue , Yan Fei , Devaty Robert P. , Choyke Wolfgang J. , Saddow Stephen E.
Published: March 2009

Hot-wall chemical vapor deposition has been used to epitaxially grow SiC layers on
porous n-type 4H-SiC substrates. The growth was carried out at different speeds on porous layers of
two different thicknesses. The quality of the SiC films was evaluated by X-ray diffraction and
photoluminescence techniques. Based on the measurements, both the growth speed and the
thickness of the porous layer buried underneath the epilayers do not appear to influence the
structural integrity of the films. The intensity of the near bandedge low temperature
photoluminescence appears stronger by a factor of two in films grown on porous layers.
Studies on Selective Growth and In Situ Etching of 4H-SiC Using a TaC Mask
Authors: Li Can Hua , Bhat I. , Chow T. Paul
Published: March 2009

We have previously reported on the selective growth of 4H-SiC epitaxial layers on a 4HSiC
substrates in a chemical vapor deposition (CVD) reactor using TaC mask. It was shown that pn
junctions fabricated using selectively grown n-layers on trench etched p-substrates have properties
similar to the mesa etched pn junction diodes, indicating good interface properties. In this paper, we
present more systematic studies on the selective growth and in-situ selective etching of 4H-SiC
using a TaC mask. The morphological evolution during selective epitaxy as a function of
crystallographic orientation was analyzed. Anisotropy in surface morphology along <11-20> and
<1-100> has been observed. Cross sectional SEM viewgraphs show lateral overgrowth on the TaC
mask, and the extent of lateral overgrowth varied with the stripe orientation. It was found that the
“growth window” for selective growth was a function of the surface area covered by the TaC mask
as well as the window opening to mask width ratios. Experiments with various window widths to
mask width ratios have been carried out to investigate the selective growth process using this mask.
‘Switch-Back Epitaxy’ as a Novel Technique for Reducing Stacking Faults in 3C-SiC
Authors: Yagi Kuniaki , Kawahara Takamitsu , Hatta Naoki , Nagasawa Hiroyuki
Published: March 2009

A new technique that reduces stacking fault (SF) density in 3C-SiC, termed switch-back
epitaxy (SBE), is demonstrated regarding its effects on morphological and electrical properties. SBE
is a homoepitaxial growth process on backside of 3C-SiC grown on undulant-Si. The key feature of
SBE, the surface polarity of residual SFs in 3C-SiC, which cannot be erased by heteroepitaxial growth
on undulant-Si, is converted from the Si-face to the C-face. The SF density on the surface of 3C-SiC
grown by SBE shows a remarkable decrease to one-seventh lower than that on undulant- Si. The
leakage current of pn-diode epitaxially fabricated on the 3C-SiC substrate grown by SBE decreases to
as low as one-thirtieth that on 3C-SiC substrate grown without SBE. These results suggest that SBE
eliminates the SFs on the surface of 3C-SiC and subsequently reduces the leakage current at
pn-junction thus fabricated.
Growth Acceleration in FLASiC Assisted Short Time Liquid Phase Epitaxy by Melt Modification
Authors: Pezoldt Joerg , Morales Francisco M. , Stauden Thomas , Förster Christian , Polychroniadis Efstathios K. , Stoemenos J. , Panknin D. , Skorupa Wolfgang
Published: March 2009

Flash lamp annealing of multilayer stack of the type SiC/Silicon overlayer(SOL)/SiC reduces
the defect densities in the 3C-SiC/Si heteroepitaxial structure. Ge and C additions to the SOL
lead to a substantial increase of the mass transfer from the upper layer to the lower SiC layer. If the
Ge content of the SOL and the flash lamp annealing conditions are properly chosen a homogeneous
layer with a 3C-SiC thickness between 150 and 200 nm can be achieved corresponding to a growth
rate between 7.5 and 10.0 +m/s. The thickening of the lower layer depends on the SOL composition.
Ge and/or C incorporation into the SOL and therefore into the Si melt enhances the mass transport
from the upper SiC layer to the lower one.
Growth of 3C-SiC on Si Molds for MEMS Applications
Authors: Reyes M. , Waits M. , Harvey S. , Shishkin Y. , Geil Bruce , Wolan J.T. , Saddow Stephen E.
Published: March 2009

A hetero-epitaxial 3C-SiC growth process in a low-pressure hot-wall CVD reactor has
been developed on planar Si (100) substrates. The growth rate achieved for this process was about
10 μm/h. The process consists of silane/propane/hydrogen chemistry with HCl used as a growth
additive to increase the growth rate. 3C-SiC has also been grown on 22, 52 and 123 +m deep etched
MEMS structures formed by DRIE of (100) Si at a rate of about 8 +m/h. Secondary electron
microscopy (SEM), atomic force microscopy (AFM) and X-ray diffraction (XRD) were used to
analyze the quality of the 3C-SiC films.
Growth of Micropipe Free Crystals on 4H-SiC {03-38} Seeds
Authors: Furusho Tomoaki , Kobayashi Ryota , Nishiguchi Taro , Sasaki M. , Hirai K. , Hayashi Toshihiko , Kinoshita Hiroyuki , Shiomi Hiromu
Published: March 2009

Growth of 4H-SiC bulk crystals on 4H-SiC {03-38} seeds was done. 4H-SiC {03-38} is
obtained by inclining the c-plane toward <01-10> at a 54.7 degrees angle. Growth on the 4H-SiC
{03-38} seed has the potential to achieve high quality crystals without micropipes and stacking faults.
Micropipe-free c-plane 4H-SiC wafers were achieved by growth on the 4H-SiC {03-38} seed. A
transmission X-ray topograph image of the micropipe free c-plane wafer revealed that there are no
macroscopic defects with displacements.
Why Are Only Some Basal Plane Dislocations Converted to Threading Edge Dislocations During SiC Epitaxy?
Authors: Zhang Ze Hong , Shrivastava Amitesh , Sudarshan Tangali S.
Published: March 2009

Dislocations were tracked from 4H-SiC epilayer to the substrate by a new method based
on combination of molten KOH etching and Reactive Ion Etching. It was found that basal plane
dislocations (BPDs) with dislocation lines parallel (or approximately parallel) to the off-cut
direction might propagate as BPDs into the epilayer, while those with dislocation lines forming
large angles (>10º) with the off-cut direction will get converted to threading edge dislocations
(TEDs). A model is proposed to explain the observations.
Effect of Crystal Defects on Reverse I-V Characteristics of 4H-SiC APDs
Authors: Soloviev Stanislav I. , Sandvik Peter M. , Arthur Steve , Matocha Kevin , Maximenko S.I. , Sudarshan Tangali S.
Published: March 2009

In this work, we investigated the effect of crystal defects on reverse I-V characteristics of
avalanche photodiodes (APDs) using electron-beam induced current (EBIC) mode of SEM. Two
types of SiC APD structures (I and II) were fabricated using 2 inch p-doped substrates with n-doped
epilayers and 3 inch n-doped substrates with p- and n- epilayers. Areas of the formed diodes were
approximately 1 mm2. The devices without any kind of electrically active 3-D structural defects
demonstrated breakdown voltages close to theoretical values, ~500 V for the APD Type I and
~1200 V for Type II APD. Stability of Type I devices was tested by applying a short pulse of high
voltage (~800 V). EBIC images, taken prior to and after the failure test, showed new defects in the
dislocation free area, which, presumably, were caused by thermal breakdown.
A New Method of Mapping and Counting Micropipes in SiC Wafers
Authors: Wan Jian Wei , Park Seung Ho , Chung Gil Yong , Carlson E.P. , Loboda Mark J.
Published: March 2009

Micropipes are considered to be a major device killer in SiC wafers. Developing a
method to count and map micropipes efficiently and accurately has been a challenging task to date.
In this work, a new method based on KOH etching and full wafer, high resolution digital imaging is
developed to map and count micropipes in both conductive and semi-insulating SiC wafers. This
method is also compared with a non-destructive method based on laser light scattering and a good
agreement between the two methods is demonstrated.