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Dongsoo Jung - One of the best experts on this subject based on the ideXlab platform.
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Brazeability of cold rolled three layer Al–7.5Si/Al–1.2Mn–2Zn–(0.04–1.0)Si/Al–7.5Si (wt.%) clad sheets
Journal of Materials Processing Technology, 2002Co-Authors: Jea-sung Ryu, Mok-soon Kim, Dongsoo JungAbstract:The effect of silicon content in the core alloy on the brazeability of three layer aluminium clad sheets was investigated using the clad sheets composed of Al–7.5wt.% Si alloy (filler, thickness: 10μm)/Al–1.2wt.% Mn–2wt.% Zn based alloy containing 0.04–1.05wt.% Si (core, 80μm)/Al–7.5wt.% Si alloy (filler, thickness: 10μm). It was revealed that the clad sheets with 0.04–0.64wt.% Si core have an excellent sagging resistance (brazeability) with a limited erosion owing to the formation of a coarsely Recrystallized Grain structure in the core during brazing. In contrast, if the Si content in the core increased to about 1%, the sagging resistance of the clad sheets decreased with severe erosion due to an incomplete recrystallization of the core during brazing.
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Brazeability of cold rolled three layer Al-7.5Si/Al-1.2Mn-2Zn-(0.04-1.0)Si/Al-7.5Si (wt.%) clad sheets
Journal of Materials Processing Technology, 2002Co-Authors: Jea-sung Ryu, Mok-soon Kim, Dongsoo JungAbstract:The effect of silicon content in the core alloy on the brazeability of three layer aluminium clad sheets was investigated using the clad sheets composed of Al-7.5wt.% Si alloy (filler, thickness: 10μm)/Al-1.2wt.% Mn-2wt.% Zn based alloy containing 0.04-1.05wt.% Si (core, 80μm)/Al-7.5wt.% Si alloy (filler, thickness: 10μm). It was revealed that the clad sheets with 0.04-0.64wt.% Si core have an excellent sagging resistance (brazeability) with a limited erosion owing to the formation of a coarsely Recrystallized Grain structure in the core during brazing. In contrast, if the Si content in the core increased to about 1%, the sagging resistance of the clad sheets decreased with severe erosion due to an incomplete recrystallization of the core during brazing. © 2002 Elsevier Science B.V. All rights reserved.
Jea-sung Ryu - One of the best experts on this subject based on the ideXlab platform.
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Brazeability of cold rolled three layer Al–7.5Si/Al–1.2Mn–2Zn–(0.04–1.0)Si/Al–7.5Si (wt.%) clad sheets
Journal of Materials Processing Technology, 2002Co-Authors: Jea-sung Ryu, Mok-soon Kim, Dongsoo JungAbstract:The effect of silicon content in the core alloy on the brazeability of three layer aluminium clad sheets was investigated using the clad sheets composed of Al–7.5wt.% Si alloy (filler, thickness: 10μm)/Al–1.2wt.% Mn–2wt.% Zn based alloy containing 0.04–1.05wt.% Si (core, 80μm)/Al–7.5wt.% Si alloy (filler, thickness: 10μm). It was revealed that the clad sheets with 0.04–0.64wt.% Si core have an excellent sagging resistance (brazeability) with a limited erosion owing to the formation of a coarsely Recrystallized Grain structure in the core during brazing. In contrast, if the Si content in the core increased to about 1%, the sagging resistance of the clad sheets decreased with severe erosion due to an incomplete recrystallization of the core during brazing.
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Brazeability of cold rolled three layer Al-7.5Si/Al-1.2Mn-2Zn-(0.04-1.0)Si/Al-7.5Si (wt.%) clad sheets
Journal of Materials Processing Technology, 2002Co-Authors: Jea-sung Ryu, Mok-soon Kim, Dongsoo JungAbstract:The effect of silicon content in the core alloy on the brazeability of three layer aluminium clad sheets was investigated using the clad sheets composed of Al-7.5wt.% Si alloy (filler, thickness: 10μm)/Al-1.2wt.% Mn-2wt.% Zn based alloy containing 0.04-1.05wt.% Si (core, 80μm)/Al-7.5wt.% Si alloy (filler, thickness: 10μm). It was revealed that the clad sheets with 0.04-0.64wt.% Si core have an excellent sagging resistance (brazeability) with a limited erosion owing to the formation of a coarsely Recrystallized Grain structure in the core during brazing. In contrast, if the Si content in the core increased to about 1%, the sagging resistance of the clad sheets decreased with severe erosion due to an incomplete recrystallization of the core during brazing. © 2002 Elsevier Science B.V. All rights reserved.
Mok-soon Kim - One of the best experts on this subject based on the ideXlab platform.
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Brazeability of cold rolled three layer Al–7.5Si/Al–1.2Mn–2Zn–(0.04–1.0)Si/Al–7.5Si (wt.%) clad sheets
Journal of Materials Processing Technology, 2002Co-Authors: Jea-sung Ryu, Mok-soon Kim, Dongsoo JungAbstract:The effect of silicon content in the core alloy on the brazeability of three layer aluminium clad sheets was investigated using the clad sheets composed of Al–7.5wt.% Si alloy (filler, thickness: 10μm)/Al–1.2wt.% Mn–2wt.% Zn based alloy containing 0.04–1.05wt.% Si (core, 80μm)/Al–7.5wt.% Si alloy (filler, thickness: 10μm). It was revealed that the clad sheets with 0.04–0.64wt.% Si core have an excellent sagging resistance (brazeability) with a limited erosion owing to the formation of a coarsely Recrystallized Grain structure in the core during brazing. In contrast, if the Si content in the core increased to about 1%, the sagging resistance of the clad sheets decreased with severe erosion due to an incomplete recrystallization of the core during brazing.
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Brazeability of cold rolled three layer Al-7.5Si/Al-1.2Mn-2Zn-(0.04-1.0)Si/Al-7.5Si (wt.%) clad sheets
Journal of Materials Processing Technology, 2002Co-Authors: Jea-sung Ryu, Mok-soon Kim, Dongsoo JungAbstract:The effect of silicon content in the core alloy on the brazeability of three layer aluminium clad sheets was investigated using the clad sheets composed of Al-7.5wt.% Si alloy (filler, thickness: 10μm)/Al-1.2wt.% Mn-2wt.% Zn based alloy containing 0.04-1.05wt.% Si (core, 80μm)/Al-7.5wt.% Si alloy (filler, thickness: 10μm). It was revealed that the clad sheets with 0.04-0.64wt.% Si core have an excellent sagging resistance (brazeability) with a limited erosion owing to the formation of a coarsely Recrystallized Grain structure in the core during brazing. In contrast, if the Si content in the core increased to about 1%, the sagging resistance of the clad sheets decreased with severe erosion due to an incomplete recrystallization of the core during brazing. © 2002 Elsevier Science B.V. All rights reserved.
Jan Tullis - One of the best experts on this subject based on the ideXlab platform.
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a new perspective on paleopiezometry dynamically Recrystallized Grain size distributions indicate mechanism changes
Geology, 2010Co-Authors: Michael Stipp, Jan Tullis, Martin Scherwath, Jan H BehrmannAbstract:The dynamically Recrystallized Grain size is a material parameter associated with dislocation creep of crystalline solids that is especially important as a flow stress indicator via piezometer calibrations. Grain sizes have been measured in many studies of deformed rocks as well as metals and ceramics, but global analyses of the frequency distribution of dynamically Recrystallized Grain sizes are lacking. Here we present the first systematic investigation of the Recrystallized Grain size distribution, for quartz. The Grain diameters, compiled from 555 samples of 31 studies of quartz mylonites deformed over a wide range of conditions, extend from ∼3 μm to 3 mm, with distinct maxima at 10–20 μm and 70–80 μm, and minima at 35–40 μm and ∼120 μm. The frequency maxima correlate with distinct microstructures and the minima with the transitions between these microstructures, which we interpret to result from the dominance of the recrystallization mechanisms of bulging, subGrain rotation, and Grain boundary migration recrystallization. These results demonstrate the necessity of distinct piezometer calibrations for different recrystallization mechanisms and highlight the importance of the Recrystallized Grain size for theoretical models of dynamic recrystallization.
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supplementary material a new perspective on paleo piezometry dynamically Recrystallized Grain size distributions indicate mechanism changes
2010Co-Authors: Michael Stipp, Jan Tullis, Martin Scherwath, Jan H BehrmannAbstract:For the present study, the quality of the compiled data sets is crucial. The complete data sets are therefore presented along with comments on the data quality in Table 1S for the natural and Table 2S for the experimental samples. Introductory remarks focus on why sampling procedure and Grain size modifications during and after deformation can only weaken rather than cause discontinuities in the Recrystallized Grain size distribution. Then we explain the basis for our data refinement and the reasons why we rely primarily on natural samples. Additional micrographs from other field examples are shown in order to demonstrate that the Tonale mylonite microstructures (Fig. 1a-c; Stipp et al. 2002a) are representative. Finally we describe the bootstrap analysis which proves the statistical significance of the bimodal Recrystallized Grain size distribution observed in the refined data set. SAMPLING AND Grain SIZE MODIFICATION
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effect of water on the dislocation creep microstructure and flow stress of quartz and implications for the Recrystallized Grain size piezometer
Journal of Geophysical Research, 2006Co-Authors: Michael Stipp, Jan Tullis, Harald BehrensAbstract:Deformation experiments on Black Hills quartzite with three different initial water contents (as-is, water-added, and vacuum-dried) were carried out in the dislocation creep regime in order to evaluate the effect of water on the Recrystallized Grain size/flow stress piezometer. Samples were deformed in axial compression at temperatures of 750°–1100°C, strain rates between 2 × 10−7 s−1 and 2 × 10−4 s−1 and strains up to 46% using a molten salt assembly in a Griggs apparatus. An increase of the initial water content at otherwise constant deformation conditions caused a decrease in flow stress, an effect known as hydrolytic weakening. The total water content of the starting material was analyzed by Karl Fischer titration (KFT) and Fourier transform infrared (IR) spectroscopy, and quenched samples were analyzed microstructurally and by IR. Changes in the dynamic recrystallization microstructure correlate with changes in flow stress, but there is no independent effect of temperature, strain rate or water content. IR absorption spectra of the deformed spectra indicate that different water contents were maintained in the three sample sets throughout the experiments. However, the amounts of water measured within the vacuum-dried (∼260 ± 40 ppm H2O), the as-is (∼340 ± 50 ppm H2O), and the water-added (∼430 ± 110 ppm H2O) samples are significantly smaller than the initial content of the quartzite (∼640 ± 50 ppm H2O). Water from the inclusions in the starting material adds to the free fluid phase along the Grain boundaries, which probably controls the water fugacity and the flow strength, but this water is largely lost during IR sample preparation. Vacuum-dried as well as water-added samples have the same Recrystallized Grain size/flow stress relationship as the piezometer determined for as-is samples. No independent effect of water on the piezometric relationship has been detected.
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the Recrystallized Grain size piezometer for quartz
Geophysical Research Letters, 2003Co-Authors: Michael Stipp, Jan TullisAbstract:D=1 0 3.56±0.27 * s 1.26 ±0.13 , with no change in slope at the regime 2–3 transition and no effect of temperature or a/b stability field. Another experimental piezometer relation for regime 1 of Hirth and Tullis [1992] differs in slope, suggesting that different recrystallization mechanisms require different piezometer calibrations. INDEX TERMS: 3902 Mineral Physics: Creep and deformation; 5120 Physical Properties of Rocks: Plasticity, diffusion, and creep; 8030 Structural Geology: Microstructures; 8159 Tectonophysics: Rheology—crust and lithosphere; 8164 Tectonophysics: Stresses—crust and lithosphere. Citation: Stipp, M., and J. Tullis, The Recrystallized Grain size piezometer for quartz, Geophys. Res. Lett., 30(21), 2088, doi:10.1029/2003GL018444, 2003.
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a Recrystallized Grain size piezometer for experimentally deformed feldspar aggregates
Tectonophysics, 1999Co-Authors: Alice Post, Jan TullisAbstract:Abstract A Recrystallized Grain size piezometer for low-temperature migration recrystallization in feldspar has been experimentally calibrated. Hot-pressed samples of fine-Grained albitic feldspar (Grain size 1–10 μm) and a natural albitic feldspar aggregate (∼150 μm) were deformed in simple shear and axial compression at a temperature of 900°C and a confining pressure of 1500 MPa. Transmission electron microscopy (TEM) verified that deformation occurred by recrystallization-accommodated dislocation creep. Grain size distributions were measured from scanning electron microscopy (SEM) photographs of polished and etched samples. The results yield a Recrystallized Grain size piezometer relationship of d=55±5·σ−0.66±0.07 where d is the geometric mean Grain size (μm) and σ the differential stress (MPa). The exponent is higher than that determined in previous studies of other materials for rotation recrystallization and high-temperature migration recrystallization, indicating that different recrystallization mechanisms have distinct Recrystallized Grain size piezometer relationships.
Hiroyuki Kokawa - One of the best experts on this subject based on the ideXlab platform.
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experimental simulation of Recrystallized microstructure in friction stir welded al alloy using a plane strain compression test
Scripta Materialia, 2008Co-Authors: Kunitaka Masaki, Y Sato, Masakatsu Maeda, Hiroyuki KokawaAbstract:Abstract The effective strain rate during friction stir welding (FSW) of Al alloy 1050 was estimated experimentally by simulating the Recrystallized Grains of the stir zone through a combination of the plane-strain compression at various strain rates and the subsequent cooling tracing the cooling cycle of FSW. With the plane-strain compression test, it was possible to simulate the Recrystallized Grain structure of the friction stir welds, and the effective strain rate was estimated to be about 2–3 s −1 .
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parameters controlling microstructure and hardness during friction stir welding of precipitation hardenable aluminum alloy 6063
Metallurgical and Materials Transactions A-physical Metallurgy and Materials Science, 2002Co-Authors: Y Sato, Mitsunori Urata, Hiroyuki KokawaAbstract:The aluminum (Al) alloys 6063-T5 and T4 were friction-stir welded at different tool rotation speeds (R), and then distributions of the microstructure and hardness were examined in these welds. The maximum temperature of the welding thermal cycle rose with increasing R values. The Recrystallized Grain size of the weld increased exponentially with increasing maximum temperature. The relationship between the Grain size and the maximum temperature satisfied the static Grain-growth equation. In the as-welded condition, 6063-T5 Al was softened around the weld center, whereas 6063-T4 Al showed homogeneous hardness profiles. Different R values did not result in significant differences in the hardness profile in these welds, except for the width of the softened region in the weld of 6063-T5 Al. Postweld aging raised the hardness in most parts of the welds, but the increase in hardness was small in the stir zone produced at the lower R values. Transmission electron microscope (TEM) observations detected a similar distribution of the strengthening precipitates in the Grain interiors and the presence of a precipitation-free zone (PFZ) adjacent to the Grain boundaries in all the welds. Microstructural analyses suggested that the small increase in hardness in the stir zone produced at the lower R values was caused by an increase in the volume fraction of PFZs.
