Advances in Materials Manufacturing Science and Technology II
Vols. 532-533
Vols. 532-533
Advanced Powder Technology V
Vols. 530-531
Vols. 530-531
Silicon Carbide and Related Materials 2005
Vols. 527-529
Vols. 527-529
Advances in Materials Processing Technologies, 2006
Vol. 526
Vol. 526
Residual Stresses VII, ECRS7
Vols. 524-525
Vols. 524-525
High-Temperature Oxidation and Corrosion 2005
Vols. 522-523
Vols. 522-523
Aluminium Alloys 2006 - ICAA10
Vols. 519-521
Vols. 519-521
Recent Developments in Advanced Materials and Processes
Vol. 518
Vol. 518
Functional Materials and Devices
Vol. 517
Vol. 517
Advanced Materials Forum III
Vols. 514-516
Vols. 514-516
Advanced Materials and Technologies
Vol. 513
Vol. 513
Advanced Structural and Functional Materials Design
Vol. 512
Vol. 512
Eco-Materials Processing & Design VII
Vols. 510-511
Vols. 510-511
Aluminium Alloys 2006 - ICAA10
Volumes 519-521
Paper Title Page
Abstract: One of the surface modification methods is proposed in this report to improve the wear
resistance of light metal such as aluminum alloys. At first alumite layer is formed on the surface of
aluminum alloy JIS A6061 which was used as the substrate with anodic oxidation treatment method.
Then thin layer of CrN is coated with sputtering method, and diamond like carbon (DLC) layer is
finally coated with ion plating method. The influence of the thickness of the alumite layer on
wear-resistance is experimentally investigated. The critical load of the coated aluminum alloy in
scratch test is measured with the surface property tester, and the wear amount of the coated
aluminum alloy is measured with the SUGA abrasion tester. The main results obtained are as
follows: (1) The critical load of coated aluminum alloy with the alumite layer in the scratch test is
higher than that without the alumite layer. (2) The wear amount of the coated aluminum alloy
increased with the increase of the thickness of the alumite layer. (3) This combined surface
treatment method can become new surface modification method because this method provided
excellent adhesive strength and good wear-resistance.
765
Abstract: The effects of the copper content on the bendability of Al-Mg-Si alloy T4 sheets were
investigated. The Al-Mg-Si alloys with less than 0.01mass%Cu, 0.4mass%Cu and 0.8mass%Cu were
prepared, and the time of solution heat treatment was changed to obtain different dispersion
conditions of the second phase particles and to obtain different shear band formation conditions by
bending. For the samples with less than 0.01mass%Cu and 0.4mass%Cu, no cracks were observed
during the bending. For the sample with 0.8mass%Cu, the maximum depth of the crack by bending
increased with the time of solution heat treatment up to 75 seconds, and then decreased over 75
seconds. The second phase particles decreased by increasing the solution heat treatment time, while
the formation of shear bands by bending increased by increasing the solution heat treatment time and
the copper content. The cause of the occurrence and the propagation of cracks by bending are
considered to be the combined effect of the shear band formation across some grains and the
micro-voids formed around the second phase particles. Improving of the bendability requires a
decrease in the size and number of the second phase particles and/or reduced shear band formation
during the bending.
771
Abstract: In dynamic dislocation-defect analysis, the thermodynamic deformation-mode signatures
are examined as the ageing proceeds. In this method, the activation volume (ν) and the mean slip
distance (λ) is simultaneously determined with the flow stress (τ) such that the inverse workhardening
slope (1/θ) can be plotted versus b2λ/ν where b is the Burgers vector. The slope of this
almost linear locus is directly proportional to the activation distance (d). Calibration with a model
alumina-dispersed high conductivity copper reveals that punched-out loops are produced up to
failure and is represented by a linear locus from 0.1 to 11 % strain. Artificial ageing of AA6111 at
180°C follows this pattern but the naturally-aged specimen manifest a distinctly different signature
which shows a transition as the GP zone-type precipitates are sheared. Furthermore by selecting a
suitable tensile-test temperature below 250K, the particle size and volume fraction can be
determined if particle shearing does not take place. The optimum size and volume fraction
necessary for sufficient strength and ductility can be assessed using this method.
777
Abstract: Two recent methods for obtaining flow stress-strain relations up to large strains of order
1.5 by channel-die compression are presented:
i) for sheet metal formability tests, composite samples have been made of glued sheet layers and
deformed at room temperature in a channel-die with the compression axis directed along one of the
sheet metal edge directions, i.e. RD or TD. The sheet plane is parallel to the lateral compression die
face. It is shown that, using a suitable lubricant, the sample deformation is homogeneous up to
strains of 1.5. Tests carried out on 5xxx and 6xxx alloys to evaluate the stress-strain relations show
that a generalized Voce law gives a good quantitative fit for the data.
ii) for high temperature plate processing, quantitative flow stress data can be obtained up to 500°C
with a rapid quench using a hot channel-die set-up. Some new results are presented here for high
strain hot PSC tests on Al-Mn and Al-Mg alloys together with microstructure analyses.
783
Abstract: Gradient-dependent plasticity where a characteristic length is involved to consider the
microstructural effect (interactions and interplaying among microstructures due to the heterogeneous
texture) is introduced into Zerilli-Armstrong model based on the framework of thermally activated
dislocation motion. Effect of initial temperature on the distributions of plastic shear strain and
deformation in adiabatic shear band (ASB), the axial compressive stress-axial compressive strain
curve, the shear stress-average plastic shear strain in ASB curve and the plastic shear strain
corresponding to the occurrence of shear strain localization is investigated. The axial deformation
within aluminum-lithium alloy specimen in uniaxial compression in strain-hardening stage is
considered to be uniform. Beyond the peak compressive stress, a single ASB with a certain thickness
determined by internal length is formed and intersects the specimen. The axial plastic deformation is
decomposed into uniform deformation and localized deformation due to the shear slip along ASB.
Lower temperature leads to earlier occurrence of shear strain localization, i.e., lower critical plastic
compressive strain, steeper post-peak shear stress-average plastic shear strain in ASB curve, higher
peak shear stress and more apparent shear strain localization. The calculated distributions of plastic
shear strain and deformation in ASB are highly nonuniform due to the microstructural effect, as
cannot be predicted by classical elastoplastic theory applicable to completely homogenous material.
The predicted average plastic shear strains in ASB for different widths of ASB agree with the
measured values for under-aged Al-Li alloy at 298K and at strain rate of approximately 103s-1.
789
Abstract: Cost-efficient designs of aluminum autobody structures consist mainly of stampings
using conventional technology. Progress in metallurgy and forming processes has enabled
aluminum body panels to achieve significant market share, particularly for hoods. Fast bake
hardening alloys with better hemming performance were developed for improved outer panel sheet
products. Specific guidelines for handling and press working were established to form aluminum
panels using similar schedules and production lines as steel parts. Stamping productivity was
improved by optimization of the trimming process to reduce sliver/particle generation and resulting
end-of-line manual rework. Both hemming formability and trimming quality not only depend on
tooling setup but also on microstructural features, which govern intrinsic alloy ductility. Targets for
the next high volume aluminum car body applications, such as roof panels and doors, require higher
strength and/or better formability. The challenges of complex stampings can be met with optimized
alloys and lubricants, with improved numerical simulation to fine-tune stamping process
parameters, and with the introduction of new technologies. Warm forming was examined as a
potential breakthrough technology for high volume stamping of complex geometries.
795
Abstract: The crystal plasticity finite element method (CPFEM) is probably the method with the
best potential to directly incorporate crystal anisotropy and its evolution into forming simulations.
However, when it comes to the simulation of bulk materials, the representation of the crystal
orientation distribution function (ODF), i.e. of the statistical texture, within the CPFEM framework
becomes a key issue for the efficiency of the approach. In this work two different approaches for
sampling the ODF are compared. The first is the so called Texture-Component-CPFEM, where the
discretisation is based on the representation of the ODF by texture components. The second
approach is based on the representation of the ODF by series expansion and uses a direct mapping
of the ODF represented in the form of C-coefficients to individual orientations as needed by the
CPFEM. Both methods are compared using the textures of Aluminum hot band as well as cold
rolled material.
803
Abstract: The crystallographic slip activity in several grains deformed by simple tension is
determined by use of in-situ deformation in combination with Electron Back Scattering Diffraction
(EBSD)-investigations and Secondary Electron (SE) imaging. This technique is also used to
determine grain lattice rotation paths of grains with different initial orientation, providing
information on basic deformation mechanisms of grains present in texture gradients. Both slip
activity and grain lattice rotation paths depend on the initial orientation and are influenced by the
neighbouring grain orientations. This indicates that predictions of the forming behaviour of
extruded profiles with a strong through thickness texture gradient relate to a very complex nature.
809
Abstract: The numerical simulation of the stretch flange forming operation of Al-Mg sheet
AA5182 was conducted with an explicit finite element code, LS-DYNA. A Gurson-Tvergaard-
Needleman (GTN)-based material model was used in the finite element calculation. A strain
controlled void nucleation rule was adopted with void nucleating particle fraction measured directly
from the as-received Al-Mg sheet. Parametric study was performed to examine the effect of void
nucleation strain on the predicted onset of ductile fracture. Critical porosity levels determined
through quantitative metallurgical analysis were adopted to predict the commencement of void
coalescence in the GTN model. The numerical results were compared to the experimental ones and
an applicable void nucleation strain was suggested.
815