The Experts below are selected from a list of 315 Experts worldwide ranked by ideXlab platform
J Dos F Santos - One of the best experts on this subject based on the ideXlab platform.
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the thermal cycle during the dissimilar friction spot welding of aluminum and magnesium alloy
Scripta Materialia, 2013Co-Authors: U F H Suhuddin, Vanessa Fischer, J Dos F SantosAbstract:The thermal cycle during dissimilar friction spot welding of Al alloy AA5754 to Mg alloy AZ31 was measured by thermocouples located in the weld region. The results revealed that the weld is exposed to a non-equilibrium Solidus Temperature induced by rapid heating and cooling. Microstructural analyses showed that the grain structure development in the stir zone was affected by grain boundary diffusion, interfacial diffusion and dynamic recrystallization, which resulted in fine equiaxed grains of Al 12 Mg 17 in the weld center.
Hajime Kato - One of the best experts on this subject based on the ideXlab platform.
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superplasticity and thickness of liquid phase in the vicinity of Solidus Temperature in a 7475 aluminum alloy
Acta Materialia, 1999Co-Authors: Yoshimasa Takayama, Tatsumi Tozawa, Hajime KatoAbstract:Abstract The Temperature dependence of superplasticity has been investigated in the range including the Solidus Temperature for a 7475 aluminum alloy. It is found that the superplastic elongation shows the maximum value in the vicinity of the Solidus Temperature at a comparatively low strain rate. Filaments are observed on the fracture surfaces of the broken specimens tested below the Solidus Temperature. Further, the thickness of a liquid phase during superplastic deformation is discussed from four aspects: flow stress, fracture surface, thermal analysis and composition analysis. The thickness of the liquid phase is estimated to be 10–60 nm for the superplastically-deformed specimen.
Laurens Katgerman - One of the best experts on this subject based on the ideXlab platform.
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tensile mechanical properties constitutive parameters and fracture characteristics of an as cast aa7050 alloy in the near Solidus Temperature regime
Materials Science and Engineering A-structural Materials Properties Microstructure and Processing, 2017Co-Authors: T Subroto, A Miroux, D G Eskin, Laurens KatgermanAbstract:Abstract The knowledge on constitutive mechanical behavior at the Temperatures close to the Solidus is essential for predicting high-Temperature deformation and fracture, e.g. cold and hot cracking of aluminum alloys. In this work we studied the tensile mechanical properties of an as-cast AA7050 alloy in a near-Solidus Temperature regime. Tensile tests were carried out using Gleeble-3800™ system at Temperatures from 400 to 465 °C and at strain rates from 0.0005 to 0.05 s −1 . The results show that the strength decreases with increasing Temperature and decreasing strain rate. Meanwhile, ductility decreases with the increase of Temperature and strain rate. The constitutive parameters were extracted by fitting the test data to the extended-Ludwik and creep-law equations. The parameters for the extended-Ludwik equation are continuous with the values from a lower Temperature regime obtained earlier, while the parameters for the creep-law equation are comparable with those obtained on other 7XXX aluminum alloys. We observed a change in fracture mode at 450 °C; from ductile transgranular to intergranular. This Temperature coincides with the discontinuity point of the Temperature-ductility slope. On the fracture surface of a sample that was deformed at 465 °C with a strain rate of 0.0005 s −1 , we observed features characteristic of micro-superplasticity. Considering the test conditions, viscous flows of incipient melt or liquid-like substances are suggested to be responsible for the formation of this feature.
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constitutive behaviour of an as cast aa7050 alloy in the sub Solidus Temperature range
IOP Conference Series: Materials Science and Engineering, 2012Co-Authors: T Subroto, A Miroux, D G Eskin, Laurens KatgermanAbstract:Aluminum alloy 7050 is of interest for aerospace industries due to its superior mechanical properties. However, its inherent solidification behaviour may augment the accumulation of residual stresses due to uneven cooling conditions upon direct-chill (DC) casting. This can increase the propensity of cold cracking (CC), which is a potentially catastrophic phenomenon in casting ingots. To predict the outcome of the aluminum casting process, ALSIM software is utilised. This software has the capability to predict CC susceptibility during the casting process. However, at the moment, ALSIM lacks the information regarding material constitutive behaviour in the sub-Solidus Temperature range, which is considered important for studying CC phenomenon. At the moment, ALSIM only has a partial constitutive database for AA7050 and misses data, especially in the vicinity of non-equilibrium Solidus (NES) point. The present work presents measurements of tensile constitutive parameters in the Temperature range between 400 °C and NES, which is for this alloy defined as 465 °C. The mechanical behaviour is tested in a Gleeble 3800 thermo-mechanical simulator. Constitutive parameters such as stress-strain curves, strain-rate sensitivity and ductility of the alloy have been measured at different test Temperatures. With these constitutive data, we expect to improve the accuracy of ALSIM simulations in terms of CC prediction, and gain more insight into the evolution of mechanical properties of AA7050 in the Temperature nearby the NES.
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Finite Element method simulation of mushy zone behavior during direct-chill casting of an AL-4.5 Pct Cu alloy
Metallurgical and Materials Transactions A, 2004Co-Authors: W.h. Kool, Laurens KatgermanAbstract:In this artide, the stresses, strains, sump depth, mushy zone length, and Temperature fields are calculated through the simulation of the direct-chill (DC) casting process for a round billet by using a finite-element method (FEM). Focus is put on the mushy zone and solid region dose to it. In the center of the billet, circumferential stresses and strains (which playa main role in hotcracking) are tensile dose to the Solidus Temperature, whereas they are compressive near the surface of the billet. The stresses, strains, depth of sump, and length of mushy zone increase with increasing casting speed. They are maximum in the start-up phase and are reduced by applying a ramping procedure in the start-up phase. Stresses, strains, depth of sump, and length of mushy zone are highest in the centre of the billet for all casting conditions considered. TS - RIS U6 - http://192.168.1.1/litbank/pdf/C2540 M4 - Citavi
Yoshimasa Takayama - One of the best experts on this subject based on the ideXlab platform.
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superplasticity and thickness of liquid phase in the vicinity of Solidus Temperature in a 7475 aluminum alloy
Acta Materialia, 1999Co-Authors: Yoshimasa Takayama, Tatsumi Tozawa, Hajime KatoAbstract:Abstract The Temperature dependence of superplasticity has been investigated in the range including the Solidus Temperature for a 7475 aluminum alloy. It is found that the superplastic elongation shows the maximum value in the vicinity of the Solidus Temperature at a comparatively low strain rate. Filaments are observed on the fracture surfaces of the broken specimens tested below the Solidus Temperature. Further, the thickness of a liquid phase during superplastic deformation is discussed from four aspects: flow stress, fracture surface, thermal analysis and composition analysis. The thickness of the liquid phase is estimated to be 10–60 nm for the superplastically-deformed specimen.
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the thickness of liquid phase during superplastic deformation in the vicinity of Solidus Temperature for a 7475 aluminum alloy
Materials Science Forum, 1999Co-Authors: Yoshimasa Takayama, Tatsumi Tozawa, Hirofumi KatoAbstract:The superplastic deformation has been studied in the Temperature range including the Solidus one for a 7475 aluminum alloy in order to investigate the relation to the thickness of a liquid phase. It is found that the superplastic elongation shows the maximum value in the vicinity of the Solidus Temperature at a comparatively-low strain rate. The thickness of a liquid phase during superplastic deformation is discussed from four aspects: flow stress, fracture surface, thermal analysis and composition analysis. The thickness of the liquid phase is estimated to be 10-60nm for the superplastically-deformed specimen.
D M Maijer - One of the best experts on this subject based on the ideXlab platform.
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tensile properties of as cast aluminum alloy aa5182 close to the Solidus Temperature
Materials Science and Engineering A-structural Materials Properties Microstructure and Processing, 2004Co-Authors: L J Colley, M A Wells, D M MaijerAbstract:Abstract In response to the demand for accurate mechanical property data in the partially solidified state, an experimental apparatus has been developed to perform tensile measurements of aluminum alloys at Temperatures close to the Solidus Temperature. Measurements of the tensile properties of an industrially direct chill cast AA5182 aluminum alloy have been carried out at Temperatures between 500 and 580 °C, at a range of strain rates between ∼10 −2 and ∼10 −4 s −1 . The fracture surfaces and microstructures of the tested specimens have been examined using optical and scanning electron microscopy in an attempt to correlate tensile properties with fracture behaviour and changes in microstructure. These properties have also been linked to the liquid fraction present in the specimen based on data found in the literature.