bluuebunny/crossref_metadata_2025 huggingface dataset:
Experimental Research on Warm Deep Drawing of Magnesium Alloy Sheet by Variable Blank Holder Force Control
Authors: Chang Qun Feng , Peng Ying Hong , Li Da Yong , Zeng Xiao Qin
Published: March 2009

A process of warm deep drawing of magnesium alloy with variable blank holder force has
been presented in this study. A hydraulic press that can realize adjustable blank holder forces was
developed and its working principle and control system introduced. A warm deep drawing mould was
fixed and warm deep drawing experiments are conducted on the hydraulic press. Different variation
schemes of the blank holder force with the stroke of the punch was tested, and compared with
experiment results. The experimental results show that adopting the variable blank holder force
technique can remarkably improve the forming performance and decrease the reduction ratio of
thickness from 15.21% to 12.35%. It is further demonstrated that the suitable blank holder force
variation scheme is an inverted V curve with the punch stroke.
Effect of Second-Phase Particles on Grain Refinement of Mg-Al-Zn Alloy during ECAE
Authors: Jin Li , Lin Dong Liang , Zeng Xiao Qin , Mao Da Li , Ding Wen Jiang
Published: March 2009

The effect of second-phase particles on the grain refinement of AZ61 and AZ91 Mg-Al-Zn
alloys with different volume fractions of β-Mg17Al12 phase particles during equal channel angular
extrusion (ECAE) has been investigated. The microstructure were observed by optical microscopy
(OM), scanning electron microscopy (SEM) and transmission electron microscopy (TEM), which
revealed that grain refinement was enhanced by second phase particles at initial stage of ECAE. And
finer grains with the high angle grain boundaries (HAGBs) and disperse second-phase particles could
be obtained in AZ61 and AZ91 after 8 passes of ECAE.
Superplastic Behavior of an Extruded Mg-Zn-Y-Zr Alloy
Authors: Tang Wei Neng , Xu Dao Kui , Chen Rongshi , Han En-Hou
Published: March 2009

A conventional extrusion has been carried out to induce significant grain refinement in
Mg-Zn-Y-Zr alloy. The results showed that good superplasticity have obtained in this extruded alloy.
The simple and rapid processing route may allow it to be put into successfully practical use in
industry. The effects of temperature and strain rate on superplastic deformation of the extruded alloy
were studied. The optimum condition with the elongation of more than 450% was found to be at
450°C and 3.3×10-4s-1. Jump tests were carried out at 300-450°C and 8.3×10-5 ~ 1.7×10-2s-1. The
activation energy for superplastic deformation at 300-450°C is 106kJ/mol and the stress exponent is
about 2.8. The superplasticity observed in this studied condition may be attributed to mechanisms of
dislocation creep mainly within large grains and grain boundary sliding (GBS) of small grains.
Texture Evolution in Rolled Mg-13wt%Li-X Alloy
Authors: Li Li , Zhou Tie Tao , Li Huan Xi , Chen Chang Qi , Wu Qiu Lin , Zhang Qing Quan
Published: March 2009

Texture evolution in Mg-13wt%Li-X alloy cold-rolled from 1.35 mm to 0.34 mm thickness
was investigated, by obtaining pole figures and orientation distribution functions (ODFs). Punching
tests were conducted to reveal the effect of texture nature on formability. It was found that: (1) the
textures of the as-received sheet are characterized by α fiber texture, a γ fiber texture and a cubic
texture in both cold-rolled and annealed conditions; (2) with thickness reduction though rolling, the
intensity of the γ fiber texture continuously increases and finally the γ fiber texture connects into
{111} tube texture, the texture of <11 0> orientation flows towards {223}<11 0> along α fiber, the
cubic texture of {001}<100> turns into {035}<100>, while some grains concentrate at {011}<41 1>
orientation; (3) good punching behavior of the cold-rolled sheet corresponds to the appearance of a
well-developed γ fiber texture.
Rolling of AZ31 Magnesium Alloy Thin Strip
Authors: Jiang Bin , Wang Jian , Ding Pei Dao , Yang Chun Mei , Pan Fu Sheng
Published: March 2009

The simulation rolling and actual rolling of AZ31 strip with a thickness of 3mm prepared
by a vertical twin roll caster (Ø250×150mm) have been made by both Gleeble-1500D thermal
simulation testing machine and Ø170×300mm rolling-mill. The influence of various rolling
parameters such as temperature (250°C, 300°C, 350°C and 400°C) and reduction (40%, 50% and
60%) on the microstructure of the rolled AZ31B thin strip have been investigated by means of
metallographic observation and grain size measurment. The results indicate that when the
temperature increases, the grain size of the rolled strip increases and the uniformity decreases. When
the reduction is 50% the grain size is 10~30μm and the grains are fine and uniform. When the
reduction is 40% or 60%, the grain size is 5~180μm and the grains are coarse in some areas. An
optimized rolling process, 350°C×50% is suggested for actual rolling and a uniform microstructure of
rolled AZ31 strip is obtained.
Hot Compression Deformation Simulation of AZ61B Magnesium Alloy
Authors: Xiao Pan , Liu Tian Mo , Peng Jian , Pan Fu Sheng , Liu Qing
Published: March 2009

The hot compression deformation behavior of AZ61B magnesium alloy has been
investigated by using a Gleeble-1500D thermal simulator. The samples were compressed to a
reduction of 50% at two temperatures (623 and 673K) with different strain rates (0.01, 0.1 and 1s-1).
The relationships between flow stress and deformation temperature were analyzed, and the
deformation activation energy and stress exponent were calculated based on the experimental results.
With aid of the optical microscopy, scanning electron microscopy (SEM) and electron back scattered
diffraction (EBSD) techniques, the microstructure and micro-texture of the deformed samples were
characterized. The effects of the temperature and strain rates on the hot compression behavior of the
AZ61B magnesium alloy have been investigated by detail analyses of the flow stress and
microstructural characteristics of the deformed samples. For the 50% compressed samples, dynamic
recrystallization occurred during the hot compression. The orientations of the dynamic recrystallized
grains with equiaxed shape were investigated by EBSD technique. The relationships among the flow
stress, dynamic recovery and recrystallization have been discussed by considering both the
temperature and strain rate effects.
Phase Analysis of Al-Mn Compounds in the AZ Magnesium Alloys
Authors: Liu Chuan Pu , Pan Fu Sheng , Wang Wei Qing
Published: March 2009

The powders of Al-Mn phases were obtained from the as-cast, as-rolled and as-extruded
AZ magnesium alloys (AZ31, AZ61) by using the extraction technology, which was found to be one
of the effective methods for analyzing Al-Mn phases in the AZ magnesium alloys. X-ray diffraction
(XRD), scanning electron microscopy (SEM) and energy dispersion X-ray detector (EDX) were used
to investigate the structure and morphology of these compound powders. The results showed that
manganese existed in both the way of Al8Mn5 phases and dissociated manganese particles in the AZ
magnesium alloys, and rolling or extrusion process did not change the type of the Al8Mn5 phases.
SEM observation showed that Al8Mn5 phases were formed mainly in dendrite and leaf shape with the
size of 15-100μm in the as-cast AZ magnesium alloys, and were broken into fine spherical fragments
with the size of about 4-5μm after rolling or extrusion.
The Cathodic Reduction Processes of SiO2 Impurity in Magnesium Electrolysis
Authors: Liu Jiang Ning , Li Bing , Song Xing Fu , Wang Jin , Yu Jian Guo
Published: March 2009

The cathodic reduction of SiO2 in KCl-CaCl2-NaCl-MgCl2 melt was studied using
tungsten wires as working electrodes. The results of cyclic voltammetrysquare wave voltammetry
and chronopotentiometry showed that the cathodic deposition of silicon is a quasi-reversible
diffusion-controlled reaction, followed by a four electrons transfer step. The results of current reversal
chronopotentiometry and thermodynamic data showed that both the silicon deposition and the side
reaction between SiO2 and magnesium result in the loss of magnesium and low current efficiency. A
35.2% current efficiency was obtained with the content of SiO2 0.2% at 700 .
Interaction between Carbon Nanotube and Mg Surface: Ab-Initio Investigation
Authors: Wan Jian Feng , Fei Yan Qiong , Wang Jian Nong
Published: March 2009

ab-initio calculations on the interaction between the single-walled carbon nanotube
(SWCN) and the Mg (0001) surface have been reported. It was found that the charge transfer from
metal surfaces to the nanotubes takes place depending on both the electronic structures of the
nanotubes and the work functions of the metal surfaces. The stable geometries for the nanotube
between two consecutive objectives with C-Mg chemical bonds formed. The interaction energy in the
most stable geometry is found to be CNT’s structural dependence. Concerning the electronic
properties, the most stable structure showed a decrease in the density of states near the Fermi level due
to the formation of C-Mg bonds enhancing the metallic character of the nanotube by the contact with
the surface. The nature of the nanotube-interface interaction for nanotubes of larger diameters has
been also discussed based on the calculated bond order.
Application of G-L Dislocation Model in Low Frequency Damping Capacities of AZ91D and SiCw/AZ91D Composites
Authors: Zhang Y.K. , Hu Xiao Shi , Wu Kun , Zheng Ming Yi
Published: March 2009

The low frequency damping capacities of commercial cast AZ91D, squeeze cast AZ91D
alloy and SiCw/AZ91D composite were studied using dynamic mechanical analyzer (DMA). The
obtained strain amplitude dependent damping could be divided into two regions. In the region of
small strain amplitude, the damping capacity was independent of the amplitude. While at high strain
region, the damping capacity increased rapidly with increasing of strain amplitude. The G-L
dislocation model was used to explain the damping capacity, and the differences of the distance
between the weak and strong pinning points were discussed. The microstructures of the alloys and
composites were observed and coincided with the analysis results according to G-L dislocation
model.
Effect of Pulsed High Energy Electron Beam on Surface Modification of AZ91 Magnesium Alloy
Authors: Lv Wei , Zhao Hui , Han Zhong , Liu Zhen
Published: March 2009

Effect of pulsed high-energy electron beam on the surface modification and the state of
surface layer and wear resistance of AZ91 magnesium alloy have been investigated in this study.
Optical microscope (OM) and X-ray diffraction (XRD) were employed to characterize the
microstructure and phase composition of the modified surface layer. It was found that the thickness of
melted layer on the surface varied with electron beam current and the numbers of pulses, the treated
surface layer exhibited higher hardness than AZ91 alloy. The friction coefficient and the wear volume
of AZ91 alloy after electron beam treatment decrease markedly. The wear resistance of treated
samples were significantly improved, which may be attributed to high hardness as a result of grain
refinement.
Rare Earth Conversion Coating of Magnesium Alloy AZ91D
Authors: Bai Li Qun , Li Di , Guo Min , Xin Jing
Published: March 2009

Rare earth chemical conversion coating of Mg alloys was studied. Corrosion and
electrochemical behavior in chloride environment were investigated with tests of evolution of
hydrogen and electrochemical measurements. The surface morphologies and composition of rare
earth conversion coating were studied through SEM, EDAX and XPS. The results showed that rare
earth conversion coatings could improve corrosion resistance and their corrosion resistance was
comparable with that of chromate coatings (HB/Z5078278). This result was further proved by
Polarization and EIS.
Application of Electrochemical Techniques to Characterization of the Corrosion Behaviors of GW63 Alloys
Authors: Guo Xing Wu , Chang Jian Wei , He Shang Ming , Fu Peng Huai , Ding Wen Jiang
Published: March 2009

The corrosion behavior of GW63 (Mg-6wt.%Gd-3wt.%Y-0.4wt.%Zr) alloys in 5% NaCl
aqueous solution has been investigated by PARSTAT 2273 instrument. The Open Circuit Potential
(ECORR) vs. time curve, cyclic polarization (Pitting Scans) curve and Electrochemical Impedance
Spectroscopy (EIS) was measured for the GW63 alloys in as-cast and T6 heat treatment conditions.
The EIS results indicated that the tendency of impedance variation for as-cast condition was
monotonic decreasing, however, the tendency of variation for T6 condition was not completely
monotonic but the total tendency was decreasing. The values of impedance of GW63 alloy at 0.1 Hz
are about 103 ohm-cm2 for as-cast and T6 condition.
Study on Phosphating on the Magnesium Alloys
Authors: Lan Wei , Sun Jian Chun , Zhou An Ruo , Qiu Hui Dong , Zhang Ding Fei
Published: March 2009

In this paper, the solution mainly containing Zn(H2PO4)2 was used to prepare phosphating
coatings on AZ31,AZ61 and AZ91 magnesium alloys. The effects of the phosphating parameters and
the composition of phosphating solution on the formation of the coatings were investigated by
orthogonal tests. The corrosion behaviors of the phosphating coatings were also studied and it is
found that there was no hydrogen evolution in at least 1h. In the last, 60~80μm organic coatings
were painted on the phosphated magnesium alloys,the organic coatings adhered to the phosphating
coating, and the anti-corrosion abilities were improved .
Microstructures and Dynamic Compression Properties of a High Reinforcement Content TiB2/Al Composite
Authors: Zhu De Zhi , Wu Gaohui , Jiang Long Tao , Chen Guo Qin
Published: March 2009

A high reinforcement content TiB2/2024Al composite with an average particle size of 8μm
was fabricated by squeeze casting technology. The dynamic compression behaviors of the composite
under varied strain rates were measured using split Hopkinson pressure bar, and its microstructure
and fracture characteristic were examined. Resluts revealed that the composite was dense and
homogenerous, and the TiB2-Al interface was clean without interfacial reactants. At high strain rate,
the TiB2/Al composite showed insensitive to the strain rate, and both the flow stress and the elastic
modulus improved little with an increase of the strain rate. The composite failed macroscopically in
shear fracture and in split, which were caused by cracking of large reinforcement particles and
interface failures under dynamic load.
Rheological Behavior and Thermo-Mechanical Coupling Analysis of Aluminum Continuous Roll Casting Process
Authors: Zhan Li Hua , Zhong Jue
Published: March 2009

According to the characteristics of transient solidification and continuous rheology in roll
casting process, and by modifying clamp system and loading way of molten metal, physical
simulation of continuous roll casting process was realized in conjunction with Gleeble-1500
thermal-mechanical simulation testing machine in the present study. And relative rheologica1
constitutive models fitting the process were set up. A method to conduct multi-nonlinear
thermo-mechanical coupling analysis suitable for aluminum strip roll casting process was explored by
the secondary development of ANSYS finite element analysis software. The variation rules of
temperature and deformation field were obtained. It has been found that the simulating models are
compared with experimental results.
Creep Behaviour and Microstructure of Magnesium Die Cast Alloys AZ91 and AE42
Authors: Wei Kun , Wei Liu Ying , Warren Richard
Published: March 2009

Tensile creep behaviour of the die-cast magnesium alloys AZ91 and AE42 has been studied
at temperatures between 85oC and 200oC and at stresses in the range from 30 to 100 MPa.
Microstructural investigations, mainly by TEM, have been performed on the selected crept samples to
characterise the microstructural change during the plastic deformation, which reveals several
phenomena related to the creep process including formation of dislocation sources, denuded zones
around grain boundaries and microvoids, and changes in the nature of intermetallic phases. The active
creep mechanisms have been discussed on the basis of the creep data in combination with the
microstructural change during creep.
Accumulative Roll-Bonding (ARB) of Sheets of Aluminium and its Commercial Alloys AA8006 and AA5754 at Ambient and Elevated Temperatures
Authors: Karlík Miroslav , Slámová Margarita , Homola Petr , Sláma P. , Cieslar Miroslav
Published: March 2009

Mechanical properties and microstructure of twin-roll cast (TRC) pure aluminium,
Al-Fe-Mn-Si (AA8006) and Al-Mg (AA5754) alloy sheets ARB processed at ambient and elevated
temperatures (200, 250, 300 and 350°C) were investigated. Processing at elevated temperatures
results in better bonding but it produces smaller increases in hardness. AA8006 specimens were
processed without any problems up to 7 cycles. The alloy AA5754 suffered from severe edge and
notch cracking since the first cycle. The strength was evaluated from tensile test and microhardness
measurements; the microstructure was examined using light microscopy, and transmission electron
microscopy. The microstructure was compared to that of conventionally cold rolled (CCR) specimens
with true strain ε of 0.8, 1.6, 2.4 and 3.2 corresponding to the strain induced by 1 to 4 ARB cycles. The
work hardening of alloy AA8006 saturated after the 3rd cycle, whereas the hardness of alloy AA5754
increased steadily up to the 5th cycle. Very fine grain structure with large fraction of high angle
boundaries was observed in both alloys after two cycles of ARB. The grains were refined to
submicrometre and nanometre size (down to 90 nm in alloy AA5754). Intensive post-dynamic
recovery was observed in AA8006 specimens. The recovery is less pronounced in the AA5754 alloy
with high concentration of solute atoms in solid solution.
Evolution of Micro-Textures within Individual Grains in Rolled Polycrystal Aluminum
Authors: Deng Yun Lai , Zhang Yong , Zhang Xin Ming
Published: March 2009

Local orientation distributions of two neighbouring grains initially orientated near
(01l)[100] and (210)[001], in a pure Al poly-crystal aggregate rolled by a reduction of 65% at room
temperature have been investigated using electron backscatter diffraction (EBSD) technique. It was
found that the rotation angles of zones adjacent to both sides of initial boundary (BP) are less than that
of zones remote from the boundary (IP), which reveals that rotation incompatibility and heterogeneity
of local orientations within individual grains during rolling. A type of improved Taylor type crystal
plasticity models, in which an added prescribed shear (APS) depending on distances from grain
boundary proposed, was established to illustrate development of micro-textures in each grain. The
results simulated by the APS-Taylor models well agree with the micro-textures examined by EBSD.
Numerical Simulation on Influence of Clearance and Friction on Wrinkling in Bending of Aluminum Alloy Rectangular Tubes
Authors: Zhao Gang Yao , Liu Yu Li , Yang He
Published: March 2009

The clearance and friction have large influence on wrinkling in rotary draw bending
process of thin-walled rectangular tube. In this paper, a three-dimension Al FEM model of rotary
draw bending of thin-walled rectangular tube is built under the ABAQUS/ Explicit environment.
Based on the model, simulation and analysis of rotary draw bending for aluminum alloy 3A21
thin-walled rectangular tube have been carried out. The results show that the height of wrinkling wave
decreases obviously with the decrease of the clearance between mandrel and tube or with the increase
of the friction coefficient between wiper die and tube; however, the effect of friction coefficient on
wrinkling becomes weaker while increasing the clearance between mandrel and tube. The
achievements of this study provide a guideline for determining the process parameters for thin-walled
rectangular tube in rotary draw bending process.
Shear Pressing for Grain Refinement of Al-Mg-Li Sheet
Authors: Du Yu Xuan , Zhang Xin Ming , Ye Ling Ying , Luo Zhi Hui
Published: March 2009

A novel shear-deformation technique, named ‘shear pressing’ (SP), was developed for
fabrication of plate-shaped fine grained metallic materials. The principle of SP is that a material is
subjected to shear deformation by utilizing pressing with inclined plane dies. A micrometer order
grain structure was obtained in an Al-Mg-Li alloy at strain of ε = -2.3 by utilizing this technique. The
grain refinement sequences during pressing were examined by electron backscatter diffraction. The
enhancement of grain refinement to the Al-Mg-Li alloy was compared with plane strain compression
(PSC) at similar strains. The effect of the shear strain on the accelerated grain refining during
compressing has been discussed.
3D FEM Simulation of Void Growth in Aluminum Single Crystals
Authors: Liu W.H. , Zhang Xin Ming , Tang Jian Guo , Du Yu Xuan
Published: March 2009

Void growth in aluminum single crystals is simulated using the finite element method, to
illustrate the effect of grain orientation on void growth, a rate dependent crystal plasticity constitutive
theory is implemented as a user-defined plasticity subroutine. A three-dimension unit cell including a
sphere void was employed using three-dimensional 12 active slip systems. The computed results for
several grain orientations are compared, which have shown that crystallographic orientation has
significant influence on growth behavior of void. And the void growth direction and shape
significantly depend on the crystallographic orientation. Due to plastic flow localization and
anisotropic behavior, void which has an initial sphere shape, develops an irregular shape and some
corners.
Modifying Effect of Al-Ti-C-P Master Alloy on Hypereutectic Al-Si Alloy
Authors: Xu Chun Xiang , Liang Li Ping , Lu Bin Feng , Xue Yong Jun , Zhang Jin Shan , Liang Wei
Published: March 2009

Al-Ti-C-P master alloy has been successfully fabricated by SHS-melting technology.
Microstructures and phase constituent of Al-Ti-C-P master alloy were investigated using X-ray
diffraction (XRD), scanning electron microscopy (SEM) and EDS. The results show that Al-Ti-C-P
master alloy comprises TiAl3, TiC, AlP and α-Al matrix. After adding 2.0 wt% Al-Ti-C-P master
alloy, microstructure and mechanical properties (after T6 treating) of ZL117 alloy has been improved
dramatically: The average grain size of primary silicon decreases from 260 to 35 μm, edges and angles
of primary silicon are passivated, the morphology of eutectic silicon changes from large needle-like
one to fine rod-like or particle-like one, and the microstructures are noticeably refined; Room
temperature tensile strength changes from 168 to 260 MPa while elevated temperature tensile strength
(at 300) varies from 88 to 125 MPa. Impact toughness and macro-hardness(HB) increases to 17
J/cm2 and 97 from the original 6.5 J/cm2 and 92.
Through-Thickness Microstructure, Texture and Strength Gradients in AA 7055 Rolled Plate
Authors: Chen J.Z. , Zhen Liang , Zhang Bao You , Cui Y.X. , Dai Sheng Long
Published: March 2009

Through-thickness microstructure, texture and mechanical property gradients in the
longitudinal section of AA 7055 rolled plate have been investigated using electron back-scattered
diffraction (EBSD) technique. Quantitative analysis of the microstructure and texture through the
plate thickness was conducted. It was found that the microstructure and texture are obviously
non-homogeneous through the plate thickness. From center to surface, more equiaxed grains are
observed. As expected, the degree of recrystallization increases with increasing the S value. The
grains in the center layer exhibited preferential orientations while the most grains near the surface
presented a random one. The strength of each observed layer has also been tested.
Characterization of Precipitation in Al-Zn-Mg-Cuand Li Containing Al-Zn-Mg-Cu Alloys after Isothermal Aging
Authors: Du Zhi Wei , Shao B.L. , Liu A.S. , Sun Z.M. , Zhang X.S. , Zhou T.T. , Chen Chang Qi
Published: March 2009

The evolution of microstructure, precipitate size, volume fraction and integrated intensity
of Al-8.0Zn-2.05Mg-1.76Cu (7055) and 7055-1.0Li alloys during isothermal ageing has been studied
by transmission electron microscopy (TEM) and synchrotron-radiation small angle X-ray scattering
(SAXS). According to the TEM results, referring to the thermodynamic phase diagram, it was found
that the addition of Li changed the types of the precipitates. T1 phase was observed in the 7055-1.0Li
alloy besides the GP zones, η' and η with variant orientations with matrix, η1、η2 and η4. The
super-lattice spots of L12 (Cu3Au) structure were probably due to the existence of Al3Li (δ') or
Al3(Zr,Li). Furthermore, the precipitation sequence has been modified in Li-containing
Al-Zn-Mg-Cu alloys. The precipitate volume fraction derived from the integrated intensity for 7055
alloy reached an plateau except ageing at 120°C and the maximum was about 0.052-0.054 in the
temperature range 140-160°C.
Microstructure and Strain Distribution Influence on Failure Properties in Eutectic AlNi, AlFe Alloys
Authors: Olaru Paul , Gottstein Günter , Pineau Andre
Published: March 2009

Eutectic AlNi, AlFe, alloys exhibit plastic strains to failure (usually in the range of 1%-
5%), that those of structural alloys. We have developed a technique to measure strains at the scale
of the microstructure and have used this method to assess the variation in failure properties with
microstructure. This method is capable of using the grayscale information in the image of a gridded
sample to obtain sub-pixel marker displacement, and can therefore accurately determine small strain
values. Microstructures that exhibit large variation in local strain distribution tend to have higher
variability in tensile properties, particularly tensile ductility, compared to microstructures that
accumulate strain more uniformly. Orientation and morphology of lamellar plates in lamellar
colonies play, also, a role in influencing the distribution of strain.
Local grain orientation, phase distribution and segregation are factors influencing the strain
distribution, and therefore the properties of these materials.
Effect of Low Temperature Rolling on Microstructure and Properties of ECAE Processed Copper
Authors: Kusnierz J.
Published: March 2009

The changes in the tensile properties, in relation to the phenomenon of shear
banding are investigated in copper, rolled at liquid nitrogen temperature and then
recrystallized, after initial processing by Equal-Channel Angular Extrusion (ECAE) at room
temperature. Increases in ductility and strength up to the fourth pass of ECAE processing
were noted, then a decrease of both properties was observed. The decrease was accompanied
by twinning and shear banding. In rolled samples, pre-cooled down to the temperature of
liquid nitrogen and initially recrystallized, the twinning and shear banding mechanisms were
the most probable mechanisms responsible for lowering the mechanical properties.
Quantifying Heterogeneous Microstructures: Core and Mantle Subgrains in Deformed Calcite
Authors: Valcke S.L.A. , Drury M.R. , de Bresser J.H.P. , Pennock G.M.
Published: March 2009

Calcite deformed by high temperature creep develops a heterogeneous microstructure
consisting of deformed and recrystallised grains. The deformed grains either contain homogeneously
distributed subgrains of similar size, or heterogeneously distributed small subgrains at grain
boundaries (mantle subgrains) and relatively large subgrains in the core of grains (core subgrains).
This paper demonstrates a method using electron backscattered diffraction (EBSD) to distinguish
between the different types of grains and subgrains and to measure their sizes separately. In
geological materials the average subgrain size, regardless of the subgrain type, is often used to
estimate the deformation stress. However, this paper shows that mantle and core subgrain types only
show a weak or no stress dependence.
The Softening of a Dispersoid-Rich Commercial Al-Mn Alloy
Authors: Ekström Hans Erik , Tangen Stian , Mishin O.V. , Östensson Lars
Published: March 2009

The microstructural evolution during annealing of a commercial Al-Mn alloy cold rolled to a high strain was investigated using EBSD and Gallium Enhanced Microscopy. The precipitation of manganese, coarsening of precipitates and tensile properties were monitored at different stages. It was found that during recovery the subgrains grow until they reach the limiting subgrain size when the driving force has been reduced to the same level as the Zener drag from the dispersoids. New grains are nucleated at constituent particles and a few are able to grow. The softening during recovery and the onset of discontinuous recrystallisation are analyzed and discussed in terms of recent theories of recovery and recrystallisation.
Recrystallization Texture of Copper as a Function of Layer Thickness in Roll-Bonded Cu-Nb Composites
Authors: Lim S.C.V. , Rollett Anthony D.
Published: March 2009

The extraordinary strength values of composites with nano-scale layers or phases have inspired much investigation into the strengthening mechanisms of laminated composites such as Cu-Nb. The annealed microstructure and texture of any material govern its mechanical properties in composites just as much as in single-phase materials yet studies on the development of annealing textures of such deformed layered composites are still very limited as compared to studies of strengthening mechanisms. Recrystallization textures of monolithic pure Cu and alloyed Cu - C19210 as well as when they are reinforced with Nb using roll-bonding are investigated. The rollbonded samples of different layered length scales were deformed to reductions of 70-90% and annealed at 300oC and 800oC for 0.5 hours. We found that the Cube and R-orientation {124}<211> were the dominant components in the recrystallized texture of monolithic pure Cu and alloyed Cu respectively. However, retained rolling texture was obtained for the sub-micron Cu layers of the composites. X-ray analysis and EBSD was used to study the recrystallization evolution of the Cu in the composites. EBSD in particular was also used to observe recrystallization for the sub-micron Cu layers. In this paper we also discuss the effect of the length scale of the Cu layer thickness on the recrystallized texture especially in the sub-micron range.
Recrystallization Investigated by X- Ray Diffraction Imaging
Authors: Wroblewski Thomas , Buffet Adeline
Published: March 2009

X-ray diffraction imaging allows the investigation of a large area of a polycrystalline specimen in a single shot. Dynamic processes like recystallization can, therefore, be studied without prior knowledge of where they occur. Even early stages of nucleation can be traced back using the information from images taken from the fully recrystallized specimen. Experiments performed at HASYLAB beamline G3 on cold rolled Cu and Al showed nucleation and growth behaviour that cannot be explained by classical models.
Superplastic Deformation Mechanism of a Zn-Al Eutectoid Alloy
Authors: Kokubo T. , Itoh Goroh , Motohashi Yoshinobu
Published: March 2009

The deformation mechanism in the nanometer grain size range has been basically
investigated from the results of microstructural observation after superplastic deformation in a
Zn-Al eutectoid alloy in which a reverse grain size dependence of superplasticity was previously
reported: flow stress increases and elongation decreases with decreasing grain size when grain size
is markedly reduced to nanometer range. By controlling the aging condition after solution treatment
and subsequent quenching, two specimens are prepared: the as-quenched specimen with ultrafine
grains of 83nm in diameter and aged specimen with normally fine grains of 2.6μm. The elongation
is confirmed to be smaller in the as-quenched specimen than in the aged specimen, although the
flow stress is lower. As a result of TEM observation on the interior of the grains, dislocations are
rare in the as-quenched specimen, while a significant density of dislocations are observed in the
aged specimen. This result strongly supports the mechanism previously proposed by Mishra et al.
that the accommodation process, i.e., the dislocation glide inside the grains, becomes more difficult
with decreasing grain size in the nanometer grain size range, even though the grain boundary sliding
as the major process becomes facilitated. Roughly assessed m-value was in accord with this
mechanism.
A Comparative Study on Superplasticity of Mg-Zn-Y-Zr Processed by ECAE and Hot Rolling
Authors: Tang Wei Neng , Yan Hong , Chen Rongshi , Han En-Hou
Published: March 2009

Superplastic deformation (SPD) behaviors of two fine-grained materials produced by
ECAE and hot rolling methods have been contrastively studied in this paper. It is found that the
optimum superplastic condition in as-ECAEed material was at 350°C and 1.7×10-3s-1 with elongation
to failure about 800%; while in as-rolled material, the largest elongation to failure about 1000% was
obtained at 480°C and 5.02×10-4s-1. Microstructure observation showed that grain evolution and
cavitation behavior were different in these two materials during superplastic deformation. The
controlled mechanisms for superplasticity, i.e. grain boundary sliding (GBS), dislocation creep and
diffusional creep, at different deformation conditions were discussed in terms of strain rate sensitivity
coefficient, stress exponent and activity energy.
Superplastic Deformation of Magnesium Alloy AZ31 under Biaxial Loading Condition
Authors: Abu-Farha Fadi K. , Rawashdeh N.A. , Khraisheh Marwan K.
Published: March 2009

Accurate constitutive modeling of superplastic deformation is critical for successful
simulation and optimization of superplastic forming. The selection of the forming pressure profiles in
gas blow forming of superplastic materials is still based on trial and error due to the limited predictive
capabilities of current models describing superplastic deformation. In general, these models are based
on uniaxial loading condition, assuming isotropic behavior. In this work, we examine the biaxial
bulge forming of AZ31 magnesium alloy using pressure profiles derived from different available
analytical models. The results clearly show the need for more accurate description of superplastic
deformation to improve predictive capabilities. In addition, a pressure profile that is generated using
FE in conjunction with a microstructure-based constitutive model is used and the results indicate
better ability to predict the height of the bulged sheet.
Research on Superplastic Forming of Supplied LY12 Aluminum Alloy for Fishing Spools
Authors: Yang Yong Shun , Chen Guo Qing , Yang X.
Published: March 2009

The superplasticity of LY12 alloy was reviewed in this paper. Complex component was
extruded by taking advantage of the superplasticity of supplied LY12 alloy. The research
demonstrates that in isothermal compression process dynamic recrystallization may occur in
supplied LY12 alloy. In superplastic forming test grain refinement was combined with initial
extrusion step utilizing dynamic recrystallization to complete grain refinement, which ensured the
superplasticity in supplied LY12. In the early stage of extrusion, using high deformation speed and
large amount of deformation can result in grain refinement, which primarily satisfied the demand of
the superplasticity. In the final stage, the forming speed decreased sharply so that the optimum
strain rate was satisfied and the complicated component can be extruded successfully. The resulted
product has reasonable flowing traces, which improves its service performance.
Effect of the Process Parameters on the Deformation during Superplastic Extrusion of Ti-6.0Al-2.0Zr-1.0Mo-1.0V Alloy
Authors: Li Miao Quan , Long L. , Li X.L. , Yu H. , Chi C.L. , Wen G.H.
Published: March 2009

In this paper, the flow stress model has been established based on the isothermal
compression data at deformation temperature of 800~1050oC, strain rate of 0.001~0.1 s-1 with the
help of the Zener-Hollomon parameter and the Arrehnius’ equation. For the forging of
Ti-6.0Al-2.0Zr-1.0Mo-1.0V alloy with 3.0 mm in thickness and 66.0 mm in height, the equivalent
stress, strain, strain rate distribution and temperature rise in the superplastic extrusion process have
been simulated through FEM. The simulated results show that the punch velocity has significant
effect on the equivalent stress, temperature rise and extrusion load.
Numerical Simulation and Experimental Investigation of High Strain Rate Superplastic Forming (SPF) of Al-6Mg-0.2Sc Alloy
Authors: Chen Ming He , Xue Y.H. , Rui Y.L. , Zhou J.H. , Wang Min
Published: March 2009

FEM analysis has proved to be a powerful investigative tool capable of encompassing all
the aspects that characterise an SPF process. In this paper, with the aid of a commercial finite element
software is used to simulate high strain rate superplastic bulging process of Al-6Mg-0.2Sc alloy sheet
box part under different technological parameters such as with and without lubrication. Base on
obtaining optimum the loading curve, the strain rate distributions and thickness distribution in
forming process by FE simulation, the relative validation experiments be carried out. It was found that
the thickness gradient of the formed parts will be effectively improved reducing the interfacial friction
by use of a lubrication at a higher strain rate forming. The results of the experiments are in good
accordance with the FE numerical predictions both in terms of thickness distribution and forming
times.
Finite Element Simulation of Superplastic Isothermal Forging Process for Nickel-Base PM Superalloy
Authors: Li Qing Hua , Li Fu Guo , Wan Q. , Li Miao Quan
Published: March 2009

The Chinese nickel-base powder metallurgy (PM) superalloy FGH96, which was
processed through hot isostatic pressing, is very difficult to deform. FGH96 superalloy has better
superplasticity in special deformation conditions and superplastic isothermal forging is the best
formation method at present. The accurate constitutive equations of the FGH96 alloy was established
depended on the isothermal compression experiments. A two dimensional and thermomechanical
coupled axisymmetric finite element(FE) model in which both part and die were taken in
consideration was established to fully simulate the FGH96 superalloy turbine disk superplastic
isothermal forging process. Some physical parameters about the turbine disk forging process, such as
load, stress field and strain field were calculated at different temperature within the forging range of
FGH96. The regularity of peak equivalent stress acted on die cavity surface, yield limit and ultimate
strength of die material during the forging process was found. Based on the regulation, peak
equivalent stress acted on cavity surface must be extremely less than yield limit of die material, the
optimized processing parameter 1050°C that is the best deformation temperature for the alloy was
determined. That was proved better in practice and high quality disk was forged.
Reproducing Kernel Particle Method Numerical Modeling of Thin Sheet Superplastic Tension Forming
Authors: Liu Hong Sheng , Yang Yu Ying , Li Chun Feng
Published: March 2009

Superplastic forming has emerged as an important manufacturing process, large
deformation always occurs during superplastic forming, time-consuming remeshing is necessary
while the finite element method (FEM) is used to analyze metal forming process. Meshless methods
with no meshes can avoid this problem and overcome those problems in FEM. In this paper a
meshless method based on the reproducing kernel particle method (RKPM) is applied to analyze
Magnesium Alloy (MB15) thin sheet superplastic tension forming. A superplastic meshless method
modeling program is set up, and background cells are used to compute the integrations in weak form
equations and the mixed transformation method (MTM) is used to impose the essential boundary
condition exactly. Numerical example demonstrates the effectiveness of the method in superplastic
forming.
First-Principles Calculations of Grain Boundary-Surface for Various Grain Boundaries with Different Energies in Aluminum
Authors: Uesugi Tokuteru , Inoue Y. , Takigawa Yorinobu , Higashi Kenji
Published: March 2009

The grain boundary surface is the excess energy of the grain boundary as the lattice on one
side of the grain is translated relative to the lattice on the other side of the grain. The maximum in the
slope of the grain boundary surface determines the ideal shear strength for the grain boundary sliding.
We presented the ideal shear strength for the grain boundary sliding in aluminum Σ3(11 2)[110] tilt
grain boundary from the first-principles calculations. The ideal shear strength for the grain boundary
sliding was much smaller than the ideal shear strength of a perfect single crystal.
The Activation Energy of Superplastic Flow above the Critical Temperature for Steel CrWMn
Authors: Wen J.B. , Chen F.X. , Zhang Ke Ke , Yang Yong Shun
Published: March 2009

By means of superplastic tensile test above the Ac1 temperature (γ→α transformation
temperature), superplastic deformation activation energy of ultrafine-grained commercial die steel
CrWMn is investigated on the basis of the Arrhenius theory equation, exp( / )
1
ε& = Aσ m −Q RT , which
indicates the resistance of the superplastic deformation. According to the Arrhenius equation, the
activation energy is estimated from the log σt vs 1/T relationship at a constant of sensitivity index of
strain rate. The results show that the strain rate sensitivity index is a constant and rather high at the
conditions of superplastic deformation for the CrWMn steel, the activation energy for superplastic
deformation of steel CrWMn above the critical temperature is 187KJ/mol, and the superplastic
deformation activation energy is approached to the grain boundary diffusion activation energy of γ-Fe.
This indicates that the grain boundary sliding (GBS) in superplastic deformation of CrWMn steel is
controlled by grain boundary diffusion. The characters of superplastic deformation of the steel above
the critical temperature, on the other hand, are also analyzed in this paper.
Scale Effects in the High Temperature Gas Pressure Forming of Electrodeposited Fine-Grained Copper Thin Sheet
Authors: Lei K. , Zhang Kai Feng , Tong M.J.
Published: March 2009

Scale effects in the high temperature gas pressure forming of electrodeposited fine-grained
copper thin sheets were investigated by a series of tests at various forming temperatures and die
apertures. The average as-deposited copper grain size was 5 μm. The geometrical parameters of the
bugling die system and the thickness of copper sheet varied in proportion. Different radius
hemisphere parts from 0.5mm to 5mm were obtained at a strain rate of 5.0×10−4 s−1, which was
controlled by pressure forces curves determined in terms of a finite element method (FEM) based on
constitutive equation proposed by Backoften in 1964. The experimental relative bulging height
(RBH) values were measured, and compared with that predicted by the same finite element method
(FEM). It was found that the experimental values of large scale parts approach to simulated values,
whereas the experimental values of small scale parts were quite different from simulated values. In
order to explain these phenomena, a grain-rotation-weakened mechanism was proposed.
Influence of Deformation Heat Treatment on the Ultra-Fine Structure of Austenitic Stainless Steel
Authors: Wang Min , Guo Hong Zhen
Published: March 2009

According to accommodate-state and big bulk 18-8 type austenitic stainless steel has the
weakness of coarse-grained and low strength. Optical microscopy，electron microscopy and X-ray
diffraction were used to analyze microstructure and grain size of austenitic stainless steel specimens
after deformation heat treatment. The paper investigates the influence of recrystallization annealing
on the ultra-fine structure of cold deformation austenitic stainless steel. The results show that
austenitic stainless steel can produce deformation-induced martensite by cold rolling deformation，
and that the content of martensite increases with deformation degree. During the annealing, ultra-fine
grains can be obtained by the reversal transformation-induced martensite(M′→
γ ). After severe cold
deformation, inside austenitic grains imported austenitic-martensite(γ /M) phase boundaries shall
serve to add a great deal of forming nucleus location for recrystallization, to enhance forming nucleus
ratio and refine grain. 1Cr18Ni9Ti austenitic stainless steel by severe cold deformation and
recrystallization annealing can acquire ultra-fine grains.
Heat Treatment of Ti2AlNb Intermetallic and its Superplastic Properties
Authors: Guo He Ping , Li Zhi Qiang
Published: March 2009

Ti2AlNb orthorhombic alloys exhibit great potential as advanced aerospace and structural
materials serviced at elevated temperature. In this paper, pre-heat treatment of as-received hot rolling
Ti-22Al-25Nb alloy was conducted. Fine, stable and equiaxed grain structure was obtained by the
pre-heat treatment. The volume fraction of B2 increased when annealing at 980°C. The
Ti-22Al-25Nb alloy showed characteristics of superplastic deformation when tested at 960°C.
Maximum elongation of 280% has been obtained at strain rate of 1.0×10-4s-1.
Investigation of Compression Deformation Behavior and Microstructure Evolution of NiAl-Cr (Mo)-Hf Alloy at Elevated Temperature
Authors: Chen Guo Qing , Ji S.H. , Zhou Wen Long , Wu C.W. , Guo Jian Ting , Huang Z.H.
Published: March 2009

NiAl-based alloy is a promising material applied in the fields of aeronautic and astronautic
instruments. In the paper the compression deformation behavior and microstructure evolution of
NiAl-Cr(Mo)-Hf alloy at elevated temperature were studied. The results demonstrate that the alloy
behaves good formability in the temperature ranging from 1320°C to 1360°C, in which the maximum
initial strain rate is about 8.3×10-4s-1 and the maximum deformation resistance is lower than 40MPa.
During compression at temperature between 1250°C and 1300°C the flow stress increased sharply
with the increasing of the deformation degree. When compression deformation at 1320°C~1360°C,
the flow stress decreased obviously and the flow stress decreased slightly after reached the maximum
value. By analyzing the microstructure evolution during compression it can be concluded that
as-casting microstructure was improved in deformation. The grains were refined and the brittle phases
of lamellar Cr(Mo) existing at NiAl matrix were broken. The porosities in as-casting material were
eliminated during compression and the density of the material increased. The fracture toughness of
the alloy increased from 6.4MPa·m1/2 to 9.8MPa·m1/2 after compression.
Superplastic Extrusion of Nano-Structured Si2N2O-Sialon
Authors: Luo Jun Ting , Zhang Qing , Li Hong Bo
Published: March 2009

Nano-structured Si2N2O-Sialon composites were prepared by liquid phase sintering
method with the amorphous nano-sized Si3N4 and nano-sized AlN powders. Nano-sized Al2O3 and
Y2O3 powders synthesized by polyacrylamide gel method were introduced as additives. SEM
examination shows the grain size of sintered body to be less than 80nm. Superplastic extrusion can be
undertaken at 1550°C with a high velocity of 0.5mm/min and a big extrusion ratio of 3.57. There are
a lot ring-shaped structure just like “annual ring” of trees in radial fracture and clear flow trace in axial
fracture, all which is very similar to deformed metal materials and approve good superplastic
deformation capability of Si2N2O-Sialon composites.