bluuebunny/crossref_metadata_2025 huggingface dataset:
Analysis of Hammering Deformation Processes by the Dynamic Explicit Finite Element Method
Authors: Cheng Li Dong , Wang Zhong Jin
Published: March 2009

Based on the dynamic analysis method and central difference explicit algorithm, a dynamic
explicit finite element code is developed for modeling the hammering deformation processes, in
which hammer velocity is calculated by the energy balance principle. The dynamic upsetting
processes of copper block under different hammer velocities are simulated using the developed code,
and the deformed configuration, the displacement and the equivalent plastic strain distribution are
investigated. Then, the calculated results are compared with that obtained by the static implicit
program, and the comparison shows that the results obtained by the developed code are nearly
identical to that obtained by the static implicit program under a low hammer velocity, and that there is
a great difference between them under a high hammer velocity, which can be explained from the
viewpoint of inertial effect and stress wave propagation effect. The research results indicate that the
developed code adequately considers the dynamic characteristic under drop hammer impact, and can
be used to analyze the effect of hammer velocity on the deformation during the hammering
deformation process.
Research on Fast Calculation of Rigid Plasticity Finite Element Method in Hot Strip Rolling
Authors: Li Chang Sheng , Song S.N. , Mei R.B. , Zhang G.L. , Liu Xiang Hua
Published: March 2009

Fast Finite Element (FFE) method had advantage of high precision and fast computing
velocity. The online application of FFE method was significance both in theory and practice. In this
paper the fast calculation of rigid plastic finite element method (RPFEM) in hot strip rolling was
developed in this paper. The results of rolling force were good agreement to the measured results. The
influence of element on calculating time and accuracy was discussed. The running time of
one-dimension search was reduced greatly by combining Newton method with Brent method.
Improved Newton method with trust region method and forced positive definite Hessian matrix
method were used to reduce the convergence time. The better initial value could be obtained by
improved mid-point integral Newton method. In addition, the influence of operating system,
hardware and software on the calculating time was also discussed. The project of temperature FFE
online calculation application in a plate mill was put forward.
A Method of Bulge Test for Determining the Work Hardening Characteristics of Sheet Metals
Authors: Gao Guang Fan , Ding Xin Wei
Published: March 2009

The bulge test has many advantages such as large deformation range and facility of
loading. But the curvature and thickness of specimens are varied at different positions of meridian,
and changed with the loading, so it's quite difficult to acquire the true stresses and true strains. Fixed
attention on the crown of specimens, this paper put forward an improved method of bulge test. 3D
coordinates of grid points on the surface of specimens are measured on each sub-step of loading by
universal toolmaker’s microscope, and then the curvatures and in-plane strains at the crown can be
acquired. The influence of springback on the curvatures at the crown is taken into account using
finite element methods based on MITC4 (mixed interpolation of tensorial components) shell
element. Thus the relationships between equivalent stresses and strains may be established, which
integrally represents the work hardening characteristics of sheet metals. Bulge tests had been done
on 316L austenite stainless steel.
Key Technologies for 3D-FE Modeling of Radial-Axial Ring Rolling Process
Authors: Guo L.G. , Yang He
Published: March 2009

Nowadays, 3D-FE Modeling and simulation is an indispensable method for the optimum
design and precise control of radial-axial ring rolling process for its complexities. In this paper, the
unique forming characteristics of radial-axial ring rolling have first been summarized, and then
some key technologies for 3D-FE modeling of the process have been presented and their solution
schemes have been given out, lastly the modeling and simulation of radial-axial ring rolling process
have been realized using elastic-plastic dynamic explicit procedure under ABAQUS environment.
The work provides an important basis and platform for the future investigations, such as forming
mechanism and laws, process optimum design and precise control.
Process Optimization of Laser Micro-Bending Using iSIGHT
Authors: Liu Jie , Guan Yan Jin , Sun Sheng , Wang Guang Chun
Published: March 2009

There are many factors, such as the laser and geometrical parameters, which influence
greatly on the laser bending process. So it is of great importance to determine these variables
properly. Considering the relationship of material properties and temperature, a 3-D
thermal-mechanical finite element analysis model for laser micro-bending of stainless steel foil is
developed based on the software MSC.Marc, and the laser micro-bending process of 0.1mm thick
stainless steel foil is implemented. The finite element method simulation process is integrated with
the optimization software package iSIGHT through secondary development. The objective function
is to realize the maximum bending angle after single laser scan, and laser power, beam diameter and
scanning velocity are regarded as the design variables. The forming process is optimized by using
genetic algorithm. The optimal result shows the bending angle can be got to the maximum
1.0332°when the laser power, beam diameter and scanning velocity are 32W, 0.17mm and
132mm/s respectively. The experiment results are in good agreement with optimal results.
Numerical Computation of a Linear Friction Welding Process
Authors: Tao Jun , Zhang Tian Cang , Liu Peng Tao , Li Jing , Mang Yu
Published: March 2009

Linear friction welding (LFW) has become a key manufacture and repair technology in the
aeronautical engine manufacturing, especially in the blisk manufacturing. The kinematic equation
during LFW was built, based on which the friction heat in the whole process was computed. With
thermal- mechanical coupling technique, and considering the geometrical non-linearity, the material
property non-linearity and the interface frictional non-linearity, a Finite Element Model (FEM) of
temperature, stress and deformation fields were constructed. The distribution contour of temperature,
plastic flow, stress and strain during LFW were plotted. The simulated temperature and axial
shortening results were also validated by experimental data.
Gas Tungsten Arc Welding and Hybrid Laser-TIG Welding Temperature Field Analysis of AZ31B Magnesium Alloy
Authors: Liang Guo Li , Yuan Shao Qiang , Zhou Guang Tao , Sun Xiao Dong , Mang Yu
Published: March 2009

In this particular work, the moving Gauss heat source model based on the gas tungsten
arc welding and a new heat source model based on the laser-TIG hybrid welding were developed by
the finite element analysis according to the physical characteristic of the TIG welding and the
laser-TIG hybrid welding, Taking into account the advice of parameter modification, the modeling
was respectively carried out by the single TIG and the laser-TIG hybrid welding for AZ31B
magnesium alloy. The welding temperature field and the weld cross-section geometry were
simulated separately with regard to dependence on the single TIG and the laser-TIG hybrid welding.
Comparing the experimentally measured value with simulated value of the weld section geometry,
the simulated and the experimentally determined weld section geometry by the single TIG welding
and the hybrid welding showed a good agreement, at the same time, the microstructures of the joint
were also discussed respectively.
Application and Research of Numerical Simulation for Rubber Like Material with MSC.Marc
Authors: Sang Jian Bing , Liu Bo , Wang Zhi Liang , Xing Su Fang , Chen Jie
Published: March 2009

This paper starts with a discussion on the theory of finite deformation and various types
strain energy functions of rubber like material, the material parameter of elastic law of Gao[3] is
estimated by experiment and numerical simulation. Because there are various types of strain energy
functions, a user subroutine is programmed to implement the strain energy function of Gao[3] into
the program of MSC.Marc, which offers a convenient method to analyze the stress and strain of
rubber-like material with the strain energy function that is needed. Two examples will be presented
in this paper to demonstrate the use of the framework for rubber like materials. One is to simulate a
foam tube in compression. The other one is to simulate a rectangle board with a circular hole. After
numerical analysis, it is proved the numerical results based on Gao model are in perfect agreement
with the results based on Mooney model and the estimated material parameters are valid.
Determination of the Kinetics for Dynamic and Static Recrystallization by Using the Flow Curves
Authors: Wang Jian , Xiao Hong
Published: March 2009

Improved methods to estimate the kinetics of dynamic and static recrystallization are
proposed in this paper. The kinetics for dynamic and static recrystallization can be evaluated by
inverse analysis of the flow curves obtained using the single-hit and double-hit hot compression
tests carried out on Gleeble 3500. The dynamic and static recrystallization volume fractions can be
seen as functions of plastic strain and time, respectively. The mathematical formulations between
the recrystallization volume fractions and the dislocation density related to the flow stress are used
in incremental forms in the study. The methods are applied to the hot compression tests of plain
carbon steel and the kinetics of dynamic and static recrystallization are gained successfully for some
conditions at elevated temperature. The results are clarified by comparing them with those reported
in previous investigations. It is confirmed that the present methods can provide accurate kinetics for
dynamic and static recrystallization with shorter time for experiment and computation.
Synthesis of Bulk Nanocrystalline Materials and Bulk Metallic Glasses by Repeated Cold Rolling and Folding (RCR)
Authors: Wilde Gerhard
Published: March 2009

Repeated cold rolling with intermediate folding (RCR) represents a technique to obtain
severe plastic deformation that avoids excessive heating at the internal interfaces and that proceeds
without the simultaneous action of a high pressure in the range of several GPa. Aside from the
opportunity to obtain amorphous bulk samples, the processing pathway also allows for synthesizing
dense, bulk nanocrystalline materials. The sequential combination of different processing routes that
drive a material to a different extent -, with different rates - and by different means from
thermodynamic equilibrium present new and attractive processing opportunities to obtain bulk
nanocrystalline or massive ultrafine grained materials that are widely unexplored. Here, an overview
is presented concerning the sequential application of different deformation methods with largely
different strain and pressure levels. The basic underlying mechanisms that can lead to ultrafine
grained or nanocrystalline microstructures for pure metals or to two-phase nanocomposites or bulk
metallic glasses for alloys are discussed and the current state of nanostructure control is highlighted
by selected examples.
Effect of Laser Parameter on the Bond Characteristics of Sn-3.5%Ag Solder Ball
Authors: Kim Jeng O , Jung Jae Pil , Lee Jae Hoon , Suh Jeong , Kang Hee Shin
Published: March 2009

Pulsed Nd;YAG laser was applied to investigate the bond characteristics of Sn-
3.5wt%Ag (hereafter, Sn-3.5Ag) solder ball. The ball diameter is 500µm, and the UBM (Under
Bump Metallurgy) on a FR4-PCB consisted of Cu/Ni/Au from bottom to top with thickness of
50µm/25µm/0.05µm, respectively. A RMA (rosin mildly activated) flux for BGA (Ball Grid Array)
was applied before laser soldering to set up the solder ball on the UBM. Laser power was 250W,
and its beam diameter at the focal point was around 250µm. Experimental results reveal that the
solder ball showed a good bonded state when the laser energy was in the range between 0.8 and 1.0
J. Laser energy lower than 0.8J caused non-wetting of the solder ball, and energy higher than 1.2J
showed crack along the UBM. Microstructure of the laser soldered Sn-3.5Ag was examined with
the number of pulse, when the frequency, pulse width and laser energy were fixed at 5 Hz, 20 ms
and 0.8 J, respectively. The IMC (Intermetallic Compound) of Ag3Sn in the solder changed from
acicular to rod type with increasing laser pulses. Ni3Sn4 was produced between the solder and the
UBM, and its thickness increased from 0.65 to 1.80µm with increasing number of pulse from 2 to 4.
These are thinner than those of general air reflow. Shear strength of the laser soldered ball with
output energy of 1 J showed 652.3 gf, and it was similar value compared to the result from hot plate
soldering, 654.5 gf.
Three-Dimensional Numerical Simulation on the Flow and Heat Transfer in the Welding Pool of Laser-Plasma Hybrid Welding
Authors: Li Zhi Ning , Du Dong , Chang Bao Hua , Wang Li
Published: March 2009

A three-dimensional model which takes into account Marangoni shear stress, buoyancy
force, and electromagnetic force in the laser-plasma hybrid welding pool is presented. Distribution
of velocity and temperature in welding pool are calculated by finite volume method (FVM).
Numerical analysis shows that the Marangoni shear stress determines flow pattern and the
electromagnetic force can widen bottom surface of welding pool. The simulation results agree well
with corresponding experimental results.
Numerical Studies of Explosive Welding of Three-Layer Cylinder Composites-Part 2
Authors: Mousavi Seiyed Ali Asghar Akbari
Published: March 2009

Finite element simulations of the experimental tests to explosively weld three layers of
Al5056, Al6061 and SS304L tube composites, using various stand-off distances and explosive
ratios, are presented in this study. The Williamsburg equations of state and Johnson-Cook
constitutive equations were used to describe the behaviors of the explosive and the tubes,
respectively. In this paper, the external parameters (dynamic angle and collision velocity) are
related to the physical parameters (shear stress and plastic strain). The numerical results showed
that very high localized plastic deformation was produced at the bond interface. Moreover, it was
found that the shear stress magnitude and signs can provide the necessary criteria for bonding. In
addition, the sufficient criterion for bonding was found to be the magnitude of the plastic strain
produced at the collision point. The new welding window based on the internal parameters is
proposed.
Hybrid Friction Stir Welding of Carbon Steel
Authors: Fujii Hidetoshi , Tatsuno Takahiro , Tsumura Takuya , Tanaka Manabu , Nakata Kazuhiro
Published: March 2009

A new welding technique called hybrid FSW was developed to decrease the tool load and
the defects during the FSW of high melting point materials. This method consists of FSW and a
laser for preheating ahead of the tool. The hybrid FSW enables the proper welding conditions to be
significantly expanded, and the joint characteristics are similar to those obtained by the normal
FSW at the same welding speeds.
Linear Friction Welding of Ti-6Al-4V Alloy: Microstructure Characterization
Authors: Ma Tie Jun , Li Wen Ya , Xu Q.Z. , Zhang Y. , Li Jing Long , Yang S.Q.
Published: March 2009

Ti-6Al-4V was successfully jointed by linear friction welding (LFW). A sound weld of
thickness of 65-115 $m was obtained under the present conditions. The weld consisted of the
superfine α+β structure, which is associated with the rapid heating and cooling processes involved
in LFW. The thermomechanically affected zone (TMAZ) was limited and comprised of the severely
deformed α and β grains. In the flash, a gradual microstructure was formed from the weld edge to
the flash edge. A martensite structure (α’) was formed besides the acicular α+β in the flash edge
owing to the fast cooling rate.
Metallurgical Investigations of Laser Welding of AISI 304 Stainless Steel
Authors: Mousavi Seiyed Ali Asghar Akbari , Gharedaghi A. , Mastoori Mohammad
Published: March 2009

Laser welding of AISI 304 stainless steel was carried out by pulsed Nd:YAG laser
machine under different welding conditions. Geometrical shape of the joints was circular butt.
Studies were focused on laser power, welding velocity, beam diameter and pulse duration.
Microstructure of welded joints was investigated by optical microscopy (OM) and scanning electron
microscopy (SEM). OM and SEM results show no evidence of grain growth in heat affected zone
(HAZ). In addition, columnar and equiaxed grains are observed in the weld metal. Various defects
such as lack of fusion, underfill, porosity, hot crack and mismatch are observed as a result of
improper welding conditions. The best welding conditions to obtain minimum defects are presented.
A Study on the Angular Distortion Control for the Multi-Pass Butt Weldment of STS 316LN
Authors: Kim Ha Geun , Shin Sang Beom , Kim Dae Soon
Published: March 2009

The purpose of this study is to establish the proper control method of angular distortion
of multi-pass STS 316LN weldment in the vacuum and cryostat vessel of the fusion reactor. To
achieve it, the predictive equation of angular distortion in the multi-pass STS 316LN weldment with
reference to welding heat input and effective bending rigidity of weldment was established using
FEA and experiment. The bending restraint degree of each weldment in the the vacuum vessels of
the fusion reactor was evaluated using FEA. Based on the prediction equation of distortion, both
proper welding deposit sequence of double sided butt weldment of STS 316LN for cryostat vessel
and proper welding sequence for the vacuum vessel were established and verified by the measured
distortion of actual welded structure.
Development of Evaluation Method for Solidification Cracking Susceptibility of Inconel600/SUS347 Dissimilar Laser Weld Metal by In-Situ Observation
Authors: Shinozaki K. , Yamamoto M. , Kawasaki A. , Tamura T. , Wen Peng
Published: March 2009

This study was carried out on the development of the evaluation method for solidification
cracking susceptibility of Inconel600/SUS347 dissimilar weld metals during laser welding. Some
dissimilar weld metals which have different ratios of Inconel600/SUS347 were prepared by TIG
welding and then were remelted on the U-type hot cracking tester by laser. Solidification cracking
behavior during hot cracking test was observed by a high speed camera and the dynamic strain,
close to the solidification crack, was evaluated. It appeared that local critical strain, for the initiation
of solidification crack, was obtained by this strain measurement method. So the solidification
cracking susceptibility could be directly evaluated based on the critical strain for different dissimilar
joint. By using this method, it was discovered that solidification cracking occurred most easily
when the ratio of Inconel600/SUS347 is 40%/60%, in the case of the Inconel600/SUS347 dissimilar
laser welded joints.
Laser Roll Welding of Dissimilar Metal Joint of Titanium to Low Carbon Steel
Authors: Ozaki Hitoshi , Ichioka Reiji , Matsuura Takashi , Kutsuna Muneharu
Published: March 2009

Titanium is one of structural materials. It has several advantages such as high corrosion
resistance and high strength-to-weight ratio. The demand of titanium structural panel and the
dissimilar joint has been increased in industry. It is well known that joining of steel and titanium is
difficult because of generating the brittle intermetallic compound. In the present work, the laser roll
welding of dissimilar metals, titanium to low carbon steel been investigated using a 2.4kW CO2
laser and a 2kW fiber laser. The effects of process parameters on the formation of intermetallic
compound at the interlayer and on the mechanical properties were investigated to get a sound
dissimilar metal joint. As a result, welded joints of titanium to low carbon steel were broken in the
base metal of low carbon steel in the tensile-shear test.
Fatigue Damage Model for Numerical Assessment of Fatigue Characteristics
Authors: Lee Chi Seung , Kim Myung Hyun , Chun Min Sung , Lee Tak Kee , Lee Jae Myung
Published: March 2009

The aim of this study is the development of a numerical technique applicable for the
fatigue assessment based on the damage mechanics approach. The generalized elasto-visco-plastic
constitutive equation, which can consider the internal damage evolution behavior, is developed in
order to numerically evaluate the material fatigue responses. Explicit information of the
relationships between the mechanical properties and material constants, which are required for the
mechanical constitutive and damage evolution equations, are derived. The performance of the
developed technique has been verified using the S-N relationship assessment for STS304 stainless
steel.
Manufacturing and Mechanical Properties of a Honeycomb Sandwich Panel
Authors: Seo Sung Il , Kim Jung Seok , Cho Se Hyun , Kim Seong Chul
Published: March 2009

Sandwich panels are widely used in the main structure of aircrafts and ships because of
their lightweight, high strength, stiffness, durability, and corrosion resistance. The present paper
proposes a manufacturing process of a carbody structure of rolling stock using a composite
honeycomb sandwich panel. The panel is made of carbon/epoxy composite faces and an aluminum
core. The faces bear bending loads and the core shearing load. A product is manufactured by lay-up
of composite material on the mold of the product in final dimensions; then cured in a large
autoclave for obtaining one body of a structure. In this study, in order to evaluate the mechanical
properties of the honeycomb sandwich panel, tensile test, compressive test, flexural test and shear
test of the face in honeycomb sandwich panel were performed. Impact test for the honeycomb
sandwich panel was also carried out. Moreover, end compression test was conducted. The results
show that the composite honeycomb sandwich panel has good properties for the carbody structure
of rolling stock.
The Features of Deformation Behavior of Ultra-Fine Grained Titanium and Aluminum Alloys under Conditions of High Strain Rate Superplasticity
Authors: Naydenkin Evgeny V. , Ratochka Il'ya V.
Published: March 2009

The stress-strain curves at high strain rate superplasticity were analyzed for Ti-6Al-4V
and aluminum 1420 industrial alloys in ultra-fine grained state produced by severe plastic
deformation. For both alloys the observed strengthening effect can be caused by grain growth under
the above mentioned conditions resulting to increase of grain boundary sliding resistance. In the
case of aluminum alloy the grain recovery can be accompanied by significant change in phase
composition which is also stimulates the recrystallization process.
Use of Ring Sample for High-Pressure Torsion and Microstructural Evolution with Equivalent Strain
Authors: Ito Yuki , Harai Yosuke , Fujioka Tadayoshi , Edalati Kaveh , Horita Z.
Published: March 2009

This study introduces a process of high-pressure torsion (HPT) using ring samples and
compares with the results of conventional disk HPT. Both types of HPT were conducted at room
temperature on pure Al and pure Cu. The microhardness was measured along the diameters of the
disks and rings. Microstructures were examined using transmission electron microscopy. When
hardness values were plotted against equivalent strain, all data points fell on a single line for each
material. There was a hardness maximum for pure Al but no such a maximum was present in pure Cu.
In pure Al, many dislocations were visible within grains up to the equivalent strain corresponding to
the hardness maximum but beyond this strain, grains with low dislocation density appear. All
materials exhibited steady state where the hardness remains constant with respect to imposed
equivalent strain. This study concludes that use of ring samples is effective as an alternative to the
disk samples.
On Grain Boundary Engineering of UFG Metals and Alloys for Enhancing their Properties
Authors: Valiev Ruslan
Published: March 2009

The concept of grain boundary (GB) engineering of ultrafine-grained (UFG) metals and
alloys is proposed for enhancement of properties by tailoring different GBs (low angle and high
angle ones, special and random, equilibrium and non-equilibrium) and formation of GB
segregations and precipitations using SPD processing. By variations of regimes and routes of SPD
processing we show for several light alloys (Al and Ti) the ability to produce UFG materials with
different grain boundaries, and this can have a dramatical effect on mechanical behavior of the
processed materials. This paper demonstrates also several new examples of this approach for
attaining superior strength and ductility as well as enhanced superplasticity at low temperatures and
high strain rates in various UFG metals and alloys.
In Situ Tensile Testing of Ultra Fine Grained Pd and Pd-Ag Alloys
Authors: Yang Ke Jing , Ivanisenko Yulia , Markmann J. , Fecht Hans Jorg
Published: March 2009

In situ tensile tests were conducted on ultra fine grained (UFG) pure Pd and Pd-x% Ag
(x=20, 60) alloys of different stacking fault energies (SFEs) with the aim to study the general
features of the deformation process of UFG materials as well as the peculiarities brought by the
alloying. Grey scale correlation analysis (GSCA) was used to determine the true strain as well as
the surface flow within the gauge length. It was shown that the largest values of strength and
uniform elongation were obtained in Pd-20% Ag alloy. The GSCA revealed different macroscopic
flow processes in this sample as compared with pure Pd and Pd-60% Ag alloy. In particular, pure
Pd and Pd-60% Ag alloy demonstrated rapid localization of plastic flow in the neck area, whereas
Pd-20% Ag samples showed a large contribution of homogenous deformation even after neck
formation. It has been proposed that larger strain hardening capacity of Pd-20% Ag alloy is related
to its lower SFE as compared with that of pure Pd: the lower is the SFE, the more difficult is the
cross slip and climb of split dislocations, which leads to enhanced dislocation storage and,
ultimately, to increased strain hardening. At the same time, further decrease of SFE in Pd-60% Ag
sample leads to development of deformation twinning and consequent reduction of strain hardening.
The dimpled structure of fracture surfaces in the samples will also be discussed in relationship to
these findings.
Applications of Differential Scanning Calorimetry on Materials Subjected by Severe Plastic Deformation
Authors: Gao Nong
Published: March 2009

Differential Scanning Calorimetry (DSC) is a thermal analysis technique that measures
the energy absorbed or released by a sample as a function of temperature or time. DSC has wide
application for analysis of solid state reactions and solid-liquid reactions in many different
materials. In recent years, DSC has been applied to analyze materials and alloys processed through
Severe Plastic Deformation (SPD). The basic principle of SPD processing is that a very high strain
is introduced into materials which achieve significant grain refinement and improve properties of
materials. This review paper presents some recent examples of the applications of DSC for
materials subjected to SPD, especially by Equal-Channel Angular Pressing and High-Pressure
Torsion.
Microstructure Evolution during High Pressure Torsion of AZ80 Magnesium Alloy
Authors: Arpacay Dogan , Yi Sang Bong , Janeček Miloš , Bakkaloglu Adem , Wagner Lothar
Published: March 2009

The microstructure evolution during high pressure torsion and its influence on the
mechanical properties of AZ80 magnesium alloy is presented in this study. Significant grain
refinement was observed after high pressure torsion, while the homogeneity of the grain structure
increases with the number of revolutions. Grain size decreases to about 50 nm after 15 revolutions.
The microhardness profiles measured at through-thickness and through-width directions show no
significant variation at different positions of the sample. Moreover, the negligible effect of the
revolution number on the microhardness value was observed.
Metals Microstructure Improving under Hard Cyclic Viscoplastic Deformation
Authors: Kommel Lembit A.
Published: March 2009

Annealed pure copper was subjected to equal-channel angular pressing (ECAP) by route
Bc for different passes number. Tensile test specimens were manufactured and subjected to hard
cyclic viscoplastic (HCV) deformation by means of the materials testing installation Instron 8516 in
strain control regime at room temperature. The specimens were cyclically deformed with a
frequency of 0.5Hz at different strain amplitudes, step-by-step increased from ±0.05 to ±2.5% for
30 cycles, up to seven test series in this study.
The microstructure of ECAP and HCV deformed samples were characterized by optical- and
transmission electron microscope, X-ray diffraction, tensile- and hardness testing methods.
The ECAP processed metal has mainly elongated subgrains with low-angle grain boundaries and
texture, oriented in direction of metal flow during latest pressing. We demonstrate that during HCV
deformation the dislocations density of ECAP processed UFG copper was decreased. The ECAP
texture was reoriented under cyclic load applied as elongated subgrains were jointed to small pieces
under this same angle to axis as texture before. The grain- and crystallite sizes were decreased,
which were accompanied with dislocation ribbons forming nearby new formed high-angle grain
boundaries. This paper builds on knowledge that the combined treatment by ECAP and followed
HCV deformation enable to improve UFG microstructure and ductility with lowering the strength
and hardness of UFG metals due to the lower dislocation density while coarse grained copper
exhibits increasing the strength and hardness.
Effect of Texture and Microstructure on Ductility of a Mg-Al-Ca Alloy Processed by Equal Channel Angular Pressing
Authors: Serebryany Vladimir , Popov Mikhail V. , Gordeev A.S. , Timofeev V.N. , Rokhlin L.L. , Estrin Yuri , Dobatkin Sergey V.
Published: March 2009

Texture and microstructure formation during equal channel angular pressing (ECAP) of
Mg-0.49%Al-0.47%Ca alloy were studied. The selected ECAP condition (route BC, N=6 passes,
true strain ε ≈ 6.8, T=300°C) ensures an ultrafine-grained structure of the alloy and basal texture,
inclined at an angle of 45-55º relative to the direction of extrusion. The expectation that such a
change of the texture, together with the refinement of microstructure, should improve the low
temperature ductility of this material was confirmed by tensile testing.
Influence of a Slip Plane Orientation with Respect to the Shear Plane of ECAP on Microstructure of Copper Single Crystal Subject to One Pressing at Room Temperature
Authors: Katayama Soichi , Miyamoto Hiroyuki , Vinogradov Alexei , Hashimoto Satoshi
Published: March 2009

This paper describes the influence of initial crystallographic orientation on the formation
of dense shear bands in pure copper single crystals subjected to equal-channel angular pressing
(ECAP) for one pass at room temperature. Local orientation change during simple shear by ECAP
traced by electron backscatter diffraction (EBSD) indicated that the shear bands were formed when
twinning plane and direction become parallel to the macroscopic shear plane and shear direction of
simple shear strain, respectively. Orientation splitting associated with shear bands have a twinning
relation. The shear bands were delineated by large-angle grain boundaries, having close relation to
twinning relation with matrix, suggesting the role of deformation twinning as their nucleation sites.
The activation of deformation twinning is suggested and can be rationalized by favorable
crystallographic orientation and critical dislocation density as indicated elsewhere by the present
authors.
Activation Volume in Fine Grained Metals from Stress Relaxation and Nano-Indentation
Authors: Champion Yannick , Nowak Sophie
Published: March 2009

Fine grained copper was studied using the stress relaxation technique and creep testing in
nano-indentation, to determine the activation volume involved in the micro-mechanism of the
deformation. This material exhibits a near-perfect elasto-plastic deformation, featured by a steep
work-hardening, after the elastic domain, followed by flow at a constant stress. Measurements of the
activation volumes in the various domains reveal the role of the dislocations and the variation in the
dislocation density in the deformation mechanism. This emphasizes the importance, in the
determination of the activation volume, of the deformation domain investigated as well as the
testing technique used and whether in both cases, the measurement is carried out in a transient
domain or condition where variation in dislocation density occurs.
Strengthening of Nickel Deformed by High Pressure Torsion
Authors: Zhang Hong Wang , Huang X. , Hansen Niels , Pippan Reinhard , Zehetbauer Michael J.
Published: March 2009

The strength of a deformed metal depends on the content of high angle boundaries, low
angle dislocation boundaries and the dislocations between the boundaries. High angle boundaries
contribute by Hall-Petch strengthening, whereas for the low angle dislocation boundaries and
dislocations between boundaries the strengthening is proportional to the square root of the dislocation
density. Based on an assumption of additivity of these contributions, the flow stresses of metals
deformed by cold rolling have been calculated successfully. In the present investigation pure Ni
(99.9%) has been deformed by high pressure torsion (HPT) to von Mises strains of 0.9, 1.7, 8.7 and 12.
The strength of the HPT Ni has been determined by Vickers microhardness (HV) measurements and
the microstructural parameters have been determined by transmission electron microscope (TEM) in
the longitudinal section. HPT has been compared with deformation by cold rolling and torsion based
on the structural evolution with strain and the stress-structure relationship. Based on an assumption of
a linear additivity of boundary strengthening and dislocation strengthening, good agreement has been
found between the calculated and the experimental flow stress.
Mechanical Properties and Microstructure Development of Ultrafine-Grained Cu Processed by ECAP
Authors: Janeček Miloš , Čížek Jakub , Dopita Milan , Král Robert , Srba Ondřej
Published: March 2009

Technical purity Cu (99.95 wt%) polycrystals have been processed at room temperature
by equal channel angular pressing. The results of mechanical tests and the microstructure
characterization by various experimental techniques are presented. The yield stress as well as the
strength were shown to increase with increasing strain and exceed the respective values of a coarsegrained
material. The microstructure development and its fragmentation after ECAP was
investigated by the TEM and EBSD. The proportion of high angle grain boundaries was found to
increase with increasing strain reaching the value of 90% after 8 ECAP passes. Two kinds of defects
were identified in ECAP specimens by positron annihilation spectrometry (PAS): (a) dislocations
which represent the dominant kind of defects, and (b) small vacancy clusters (so called microvoids).
The main increase of defect density was found to occur during the first ECAP pass. PAS analysis
indicated that in the specimens subjected to one ECAP pass the mean dislocation density ρD and the
concentration of microvoids cν exceeded the values of 1014 m-2 and 10-4 at.-1, respectively. After 4
passes, the number of defects becomes saturated and practically does not change with increasing
strain.
Nanostructured Shape Memory TiNi Alloy Processed by Severe Electroplastic Deformation
Authors: Stolyarov Vladimir V.
Published: March 2009

Electropulse current effect during cold rolling on deformability, nanostructure formation
and mechanical behavior in coarse-grained (CG) and ultrafine-grained (UFG) TiNi alloys enriched
by nickel is investigated. The UFG sample subjected to cold rolling with current has a fracture
strain (е = 1.91) which is higher than that without a current (е = 0.59). As a result of cold rolling
with a current and a subsequent annealing at 400-450 °C, nanostructure is formed in both alloys,
which leads to a significant enhancement of yield and ultimate stresses. It has been shown that the
efficiency of electroplastic rolling depends on the purity of the alloys.
Microstructure Development and Precipitation Effects in Ultra Fine Grained Mg-3Tb-2Nd Alloy Prepared by High Pressure Torsion
Authors: Čížek Jakub , Procházka Ivan , Smola Bohumil , Stulíková Ivana , Vlach Martin , Islamgaliev Rinat K. , Kulyasova Olya B.
Published: March 2009

Mg-Tb-Nd ternary alloy represents a novel hardenable Mg-based alloy with enhanced
strength and favorable creep properties. In the present work we studied microstructure of ultra fine
grained (UFG) Mg-Tb-Nd alloy prepared by high pressure torsion (HPT). Lattice defects introduced
into the specimen by the severe plastic deformation play a key role in physical properties of UFG
specimens. It is known that positron lifetime (PL) spectroscopy is highly sensitive to open volume
defects (like vacancies, dislocations, etc.). Therefore, PL spectroscopy is an ideal tool for defect
characterizations in the HPT deformed specimens. In the present work we combined PL studies with
transmission electron microscopy and microhardness measurements. After detailed characterization
of the as-deformed structure, the specimens were step-by-step isochronally annealed and we
investigated the development of microstructure with increasing temperature.
Evaluation of Reshaping Methods for Multi-Pass Equal Channel Angular Extrusion
Authors: Foley D.C. , Barber R.E. , Im J.T. , Onipede B. , Hartwig K.T.
Published: March 2009

Equal Channel Angular Extrusion is a widely adopted severe plastic deformation process capable of
imparting large amounts of strain in a material via multiple passes through the die. In order to
facilitate reinsertion of worked bars for multipass processing, reshaping is often required. Although
this topic is rarely discussed in the literature, it is a significant step that can influence processing
efficiency. This paper presents several reshaping options and makes recommendations for method
selection based on the authors’ experiences with each.
Deformation Behaviour of an Ultra-Fine Grained Al6082 Alloy
Authors: Sabirov Ilchat , Estrin Yuri , Barnett Matthew R. , Timokhina Ilana B. , Hodgson Peter
Published: March 2009

This work focuses on the effect of strain rate on the deformation behaviour of an ultrafine
grained Al alloy 6082 produced by equal channel angular pressing. The uniform tensile
elongation was found to increase with decreasing strain rate very substantially. This effect is
discussed in terms of the mechanisms that control plastic deformation of the alloy.
Mechanical Behaviour and Microstructure Evolution of Severely Deformed Two-Phase Titanium Alloys
Authors: Zherebtsov Sergey V. , Mironov Sergey , Murzinova Maria A. , Salishchev S. , Semiatin S. Lee
Published: March 2009

Microstructure evolution and mechanical behavior of alpha/beta Ti-6Al-4V (VT6) and
near-beta Ti-5Al-5Mo-5V-1Cr-1Fe (VT22) titanium alloys during uniaxial compression at 600°C to
a high strain of 70% was studied. The plastic-flow response for both alloys is characterized by
successive stages of strain hardening, flow softening, and steady-state flow. During compression the
lamellae spheroidized to produce a partially globular microstructure. Globularization in VT6 is
associated with the loss of the initial Burgers-type coherency between the alpha and beta phases and
the subsequent individual deformation of each phase. The misorientations of boundaries increase to
the high-angle range by means of the accumulation of lattice dislocations. In VT22 alloy the alpha
phase evolves similar to that in VT6 alloy, while in the beta phase mainly low-angle boundaries are
observed even after 70 pct. reduction.
Mechanical Properties of Ti–6Al–4V Titanium Alloy with Submicrocrystalline Structure Produced by Multiaxial Forging
Authors: Salishchev Gennady A. , Zherebtsov Sergey V. , Malysheva Svetlana , Smyslov A. , Saphin E. , Izmaylova N.
Published: March 2009

A comparative investigation of mechanical properties of Ti–6Al–4V titanium alloy with
coarse-grained (400 m), microcrystalline (10 µm) and submicrocrystalline (0.4 µm) structures in
the temperature range 20–500°C has been carried out. The submicrocrystalline structure was
obtained by multiaxial isothermal forging. The alloys with the coarse-grained and microcrystalline
structures were used in a heat-strengthened condition. The microstructure refinement increases both
the strength and fatigue limit of the alloy at room temperature by about 20%. The strength of the
submicrocrystalline alloy is higher than that of the microcrystalline alloy in the range 20 - 400°C.
Long-term strength of the submicrocrystalline specimens below 300°C is also considerably higher
than that of the other conditions. However, the creep strength of the submicrocrystalline alloy is
slightly lower than that of the heat-strengthened microcrystalline alloy already at 250°C. The impact
toughness in submicrocrystalline state is lower especially in the samples with introduced cracks.
Additional surface modification of submicrocrystalline alloy by ion implantation gives a
considerable increase in the fatigue limit. Advantages of practical application of submicrocrystalline
titanium alloys produced by multiaxial isothermal forging have been evaluated.
On the Effect of Deformation Mode on Fatigue: Simple Shear vs. Pure Shear
Authors: Vinogradov Alexei , Yasuoka Shintaro , Hashimoto Satoshi
Published: March 2009

The role of the deformation pre-history in high-cycle fatigue properties of copper
produced by severe plastic deformation is discussed. The focus is placed on comparison of the
structures and mechanical behaviours of two types specimens produced either by rolling or by ECAP,
i.e. by the pure shear or simple shear mode, respectively. It is shown that the deformation either by
simple or pure shear mode to the same equivalent strain results in alike mechanical properties, both
monotonic and cyclic. The significant influence of the initial stages of strain hardening on fatigue is
highlighted.
Fatigue-Crack-Growth Behavior of Ultrafine-Grained Al-Mg-Sc Alloy Produced by ECAP
Authors: Avtokratova Elena , Sitdikov Oleg , Kaibyshev Rustam , Watanabe Yoshimi
Published: March 2009

Fatigue-crack-growth in an ultrafine-grained (UFG) Al-6%Mg-0.3%Sc alloy is
investigated in conjunction with a precise analysis of the fracture surface. The comparison of the
crack growth behavior of the UFG and ordinary polycrystalline materials has shown that the fatigue
crack growth rate in the UFG alloy is higher than that in the coarse-grained material only in the
near-threshold region. In the intermediate fatigue stage, propagation of the fatigue-crack in the UFG
structure becomes insensitive to the grain size. At larger stress-intensity-factor-increments, K, the
crack resistance of the UFG material is better than that of un-ECAPed specimen. Analysis of the
surface features indicates that such inhibition of the crack growth in the UFG structure upon
increasing K may be related to the gradual transition from intergranular- to transgranular mode of
fatigue fracture.
Influence of Reversible Hydrogen Alloying on Nanostructure Formation in Titanium Alloys Subjected to Severe Plastic Deformation
Authors: Murzinova Maria A. , Salishchev Gennady A.
Published: March 2009

The method for production of a structure with a grain size of 30-40 nm in two-phase
titanium alloys is proposed. It is shown, that the nanostructure can be formed in billets of
150×70×15 mm, and sheets of 250×150×1 mm. The method consists of several steps including
hydrogen alloying of the alloy, heat treatment, warm deformation and finally dehydrogenating
vacuum annealing.
α-, α+β and β-titanium alloys have been investigated. Hydrogen content varied in the range 0.1–
30 at. %. Microstructure was examined using optical, scanning, transmission electron microscopy
and X-ray analysis after every step of the treatment.
The investigations have shown that a specific character of phase transformations in hydrogenated
titanium alloys plays a leading role in formation of nanostructure. The effect of dissolved hydrogen
on dynamic recrystallization in α- and β- phases is of a secondary importance. Additional
refinement in structure is observed in the deformed alloys after vacuum annealing, if its temperature
is less than the temperature of their deformation.
The work was focused on the optimization of hydrogen content and deformation conditions with
the aim to create the nanostructure in titanium alloys and to enhance their mechanical properties.
Study of Deformation and Fracture of Submicrocrystalline Aluminum Alloys by Acoustic Emission Method
Authors: Nikulin Sergey A. , Khanzhin V.G. , Dobatkin Sergey V. , Zakharov Valerij V. , Kopylov V.I. , Rostova T.D. , Rogachev S.A.
Published: March 2009

The deformation and fracture of submicrocrystalline aluminum Al-6%Mg and Al-
6.1%Mg-0.3%Sc-0.1%Zr alloys after severe plastic deformation (SPD) by equal channel angular
pressing (ECAP) as well as the same convenient alloys were investigated by acoustic emission (AE)
method. ECAP resulted in predominantly submicrocrystalline structure with high angle grain
boundaries and grain sizes ~ 100-400 nm in Al-6.1%Mg-0.3%Sc-0.1%Zr alloy and ~ 300-700 nm
in Al-6%Mg alloy. The AE measurements carried out during material tension tests give new
information regarding the processes deformation and fracture in materials and, together with the
methods of microstructure, phase and fractography analysis.
High Strength Ti of Substantial Interstitial Contents Produced by Back Pressure Equal Channel Angular Consolidation of Dehydrided Particles
Authors: Xu Wei , Wu Xiao Lin , Sadedin D. , Wellwood Grant , Xia Kenong
Published: March 2009

Back pressure equal channel angular (BP-ECA) processing was utilised to consolidate a
dehydrided (DH) Ti powder of high interstitial content (1.15 wt.% O, 0.09 wt.% N) at 630°C into
fully dense bulk ultrafine-grained (UFG) Ti. The consolidated samples showed an increase in the
contents of oxygen (1.34 wt.%) and nitrogen (0.3 wt.%). The measured densities of 4.53 g/cm3 for
the consolidated samples after 1 and 3 passes were very close to the theoretical value of pure Ti.
TEM revealed the formation of a bimodal microstructure in the one-pass sample, comprising
equiaxed grains of several micrometers in size with ultrafine grains of the order of 100 nm
uniformly distributed at the triple grain junctions. Most grains had high-angle grain boundaries with
some boundaries exhibiting non-equilibrium characteristics. Upon further BP-ECA processing to
three passes, the micrometer-sized grains were refined down to the ultrafine level and copious
nanoscale deformation twins were introduced by severe plastic strain into those ultrafine grains of
the order of 100 nm. As a result of high interstitial contents and refined grains, the sample after
processing for 3 passes exhibited remarkably enhanced true yield and ultimate strengths of 1510
and 2050 MPa, respectively. Significantly, a noticeable compressive ductility was simultaneously
attained despite such a high interstitial content, thanks probably to the non-equilibrium grain
boundaries, bimodal grain structure and the occurrence of deformation twinning.