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Zenji Horita - One of the best experts on this subject based on the ideXlab platform.
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incremental feeding high pressure sliding for grain refinement of large scale sheets application to inconel 718
Metallurgical and Materials Transactions A-physical Metallurgy and Materials Science, 2018Co-Authors: Yoichi Takizawa, Takahiro Masuda, Kyohei Watanabe, Manabu Yumoto, Yoshiharu Otagiri, Kosei Sumikawa, Yuta Kanai, Zenji HoritaAbstract:This study updates a process of high-pressure sliding (HPS) recently developed as a severe plastic deformation process under high pressure for grain refinement of sheet samples. The updated version, which we call the incremental feeding HPS (IF-HPS), consists of sliding for SPD and feeding for upsizing the SPD-processed area so that, without increasing the capacity of processing facility, it is possible to cover a much larger area with an SPD-processed ultrafine-grained structure with a grain size of ~ 120 nm. For the IF-HPS processing, anvils with flat surfaces but without grooves are used in an unconStrained condition, and the feeding distance is set equal to the deformed width. A Ni-based superalloy (Inconel 718) is processed by the IF-HPS under 4 GPa at room temperature, and it is possible to obtain an SPD-processed sheet with dimensions of approximately 100 × 100 × 1 mm3. Strain distribution and evolution were examined by hardness measurement and simulation using a finite element method. Tensile tests were conducted using tensile specimens extracted from the IF-HPS-processed sheet. Advent of high Strain Rate superplasticity with the total elongation of more than 400 pct was confirmed by pulling the tensile specimens with an Initial Strain Rate of 2.0 × 10−2 s−1 at a temperature as low as 1073 K. The formability of the IF-HPS-processed sheet was confirmed by successful cup forming. It was also confirmed that the restoration after the superplastic deformation was feasible by subjecting to conventional heat treatment used for Inconel 718.
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superplasticity of inconel 718 after processing by high pressure sliding hps
Materials Science and Engineering A-structural Materials Properties Microstructure and Processing, 2017Co-Authors: Yoichi Takizawa, Takahiro Kajita, Petr Kral, Takahiro Masuda, Kyohei Watanabe, Manabu Yumoto, Yoshiharu Otagiri, Vaclav Sklenicka, Zenji HoritaAbstract:Abstract This study reports a production of a superplastic Ni-based superalloy (Inconel 718) using a process of severe plastic deformation through high-pressure sliding (HPS). The grain size of the alloy was reduced to ~120 nm by operating the HPS process under 4 GPa at room temperature with a recently upscaled facility. The ultrafined-grained structure was well retained even after annealing at 1173 K for 1 h. Tensile tests were conducted in air at a testing temperature in the range of 973–1173 K with an Initial Strain Rate of 5.0×10 −4 –2.0×10 −2 s −1 . Superplastic elongation more than 400% were attained at all testing conditions except at 973 K. High-Strain Rate superplasticity (defined with Strain Rates higher than 1×10 −2 s −1 ) was achieved at temperatures higher than 1073 K. Electron back scatter diffraction analyses revealed that a preferential orientation of the grains was developed by the HPS processing but it was randomized with tensile deformation. Evaluation of the Strain Rate sensitivity and the activation energy for the superplastic deformation confirmed that the superplasticity of Inconel 718 was controlled by grain boundary sliding through lattice diffusion.
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ultrafine grained magnesium lithium alloy processed by high pressure torsion low temperature superplasticity and potential for hydroforming
Materials Science and Engineering A-structural Materials Properties Microstructure and Processing, 2015Co-Authors: Hirotaka Matsunoshita, Kaveh Edalati, Zenji Horita, Mitsuaki FuruiAbstract:Abstract A Mg–Li alloy with 8 wt% Li was processed by severe plastic deformation (SPD) through the process of high-pressure torsion (HPT) to achieve ultrafine grains with an average grain size of ~500 nm. Tensile testing with an Initial Strain Rate of 10 −3 s −1 showed that the alloy exhibited superplasticity at a temperature of 323 K or higher. Tensile testing in boiling water confirmed that the specimens were elongated to 350–480% at 373 K under the Initial Strain Rates of 10 −3 s −1 to 1 0 −2 s −1 with a Strain Rate sensitivity of ~0.3. The current study suggests that not only superplastic forming but also superplastic hydroforming should be feasible after the grain refinement using the HPT method.
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grain refinement and high Strain Rate superplasticity in alumunium 2024 alloy processed by high pressure torsion
Materials Science and Engineering A-structural Materials Properties Microstructure and Processing, 2015Co-Authors: Zenji Horita, Ali AlhamidiAbstract:Abstract An Al-2024 alloy was processed by high-pressure torsion (HPT) to produce an ultrafine-grained structure with a grain size of ~240 nm. A maximum elongation of ~750% was attained with an Initial Strain Rate of 1×10−2 s−1 at 673 K, demonstrating the advent of high Strain Rate superplasticity through grain refinement by the HPT processing. Evaluation of the Strain-Rate sensitivity and the activation energy for the deformation confirmed that grain boundary sliding through grain boundary diffusion is the Rate-controlling process for the superplastic deformation of the HPT-processed Al-2024 alloy.
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exceptional superplasticity in an az61 magnesium alloy processed by extrusion and ecap
Materials Science and Engineering A-structural Materials Properties Microstructure and Processing, 2006Co-Authors: Yuichi Miyahara, Zenji Horita, Terence G LangdonAbstract:Abstract Experiments were conducted on a commercial AZ61 alloy to evaluate the potential for achieving an ultrafine grain size and superplastic ductilities through the use of the EX-ECAP two-step processing procedure of extrusion plus equal-channel angular pressing. The results show that EX-ECAP gives excellent grain refinement with grain sizes of ∼0.6 and ∼1.3 μm after pressing at 473 and 523 K, respectively. The alloy processed by EX-ECAP exhibits exceptional superplastic properties including a maximum elongation of 1320% after pressing through four passes when testing at 473 K with an Initial Strain Rate of 3.3 × 10 −4 s −1 . This result compares with an elongation of ∼70% achieved in the extruded condition without ECAP under similar testing conditions.
Terence G Langdon - One of the best experts on this subject based on the ideXlab platform.
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properties of a zk60 magnesium alloy processed by high pressure torsion
Journal of Alloys and Compounds, 2014Co-Authors: Seyed Alireza Torbatisarraf, Terence G LangdonAbstract:Abstract An extruded ZK60 magnesium alloy with an Initial grain size of ∼9.4 μm was processed by high pressure torsion (HPT) for up to 5 revolutions and microstructural observations were carried out using optical and scanning electron microscopy. Measurements of the Vickers microhardness over the disk surfaces revealed lower values in the central areas of the disks after low numbers of HPT turns but with a reasonable level of homogeneity across the disks after processing by HPT through 5 turns at 2.0 GPa. The average grain size after 5 revolutions was ∼1.0 μm. Samples were processed by HPT through 5 turns and then tested in tension at a temperature of 473 K. The results show the occurrence of superplastic behavior with a maximum elongation to failure of about 535% when testing with an Initial Strain Rate of 1.0 × 10−4 s−1. These results are consistent with earlier data obtained on the ZK60 alloy after processing by equal-channel angular pressing (ECAP) but the elongations to failure are lower because of using miniature tensile specimens cut from the HPT disks.
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the evolution of delta phase in a superplastic inconel 718 alloy
Journal of Materials Science, 2007Co-Authors: Yi Huang, Terence G LangdonAbstract:An Inconel 718 sheet alloy was tested in tension at a temperature of 965°C and an Initial Strain Rate of 10−4 s−1 corresponding to the conditions for optimum superplastic deformation. Detailed observations and quantitative measurements record the evolution of the δ-phase during tensile deformation. The experiments show that the total precipitation of the δ-phase increases with Strain but there is a decrease with Strain in the number density of the needle/plate δ-phase particles and a corresponding increase with Strain in the number density of the blocky/globular δ-phase particles.
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the development of superplastic ductilities and microstructural homogeneity in a magnesium zk60 alloy processed by ecap
Materials Science and Engineering A-structural Materials Properties Microstructure and Processing, 2006Co-Authors: Roberto B Figueiredo, Terence G LangdonAbstract:An extruded ZK60 magnesium alloy was processed by equal-channel angular pressing (ECAP) and then tested in tension at elevated temperatures. The results show the alloy is superplastic at a testing temperature of 473 K with an optimum ductility of ~1310% when using an Initial Strain Rate of 2.0 × 10?4 s?1. The results demonstRate that optimum superplasticity is achieved at intermediate Strain Rates and there are decreases in the elongations to failure at both faster and slower Strain Rates. Microhardness measurements were taken both on the cross-sectional plane and along the axial direction after processing by ECAP. These measurements show the alloy is essentially homogeneous in the as-pressed condition.
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exceptional superplasticity in an az61 magnesium alloy processed by extrusion and ecap
Materials Science and Engineering A-structural Materials Properties Microstructure and Processing, 2006Co-Authors: Yuichi Miyahara, Zenji Horita, Terence G LangdonAbstract:Abstract Experiments were conducted on a commercial AZ61 alloy to evaluate the potential for achieving an ultrafine grain size and superplastic ductilities through the use of the EX-ECAP two-step processing procedure of extrusion plus equal-channel angular pressing. The results show that EX-ECAP gives excellent grain refinement with grain sizes of ∼0.6 and ∼1.3 μm after pressing at 473 and 523 K, respectively. The alloy processed by EX-ECAP exhibits exceptional superplastic properties including a maximum elongation of 1320% after pressing through four passes when testing at 473 K with an Initial Strain Rate of 3.3 × 10 −4 s −1 . This result compares with an elongation of ∼70% achieved in the extruded condition without ECAP under similar testing conditions.
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a two step processing route for achieving a superplastic forming capability in dilute magnesium alloys
Scripta Materialia, 2002Co-Authors: Zenji Horita, Kiyoshi Matsubara, Koichi Makii, Terence G LangdonAbstract:Superplastic ductilities were achieved in a dilute magnesium alloy containing 0.6% Zr through the use of a two-step processing procedure in which the basal planes are Initially aligned through extrusion and the grain size is then refined using equal-channel angular pressing. The results show a maximum tensile elongation of >400% at 573 K when using an Initial Strain Rate of 3.3×10?4 s?1.
Rajiv S Mishra - One of the best experts on this subject based on the ideXlab platform.
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serration behavior and negative Strain Rate sensitivity of al0 1cocrfeni high entropy alloy
Intermetallics, 2017Co-Authors: Mageshwari Komarasamy, Karthik Alagarsamy, Rajiv S MishraAbstract:Abstract Temperature dependent deformation mechanism of Al 0.1 CoCrFeNi high entropy alloy (HEA) was studied using monotonic and Strain Rate jump tests at various test temperatures in a coarse-grained single phase FCC HEA. The tensile properties of Al 0.1 CoCrFeNi HEA exhibited a modest temperature dependence in the tested range of 300–673 K. At an Initial Strain Rate of 10 −5 s −1 , the serration type was a function of the test temperature. Furthermore, the Strain Rate sensitivity of the flow stress changed from positive to zero to negative once the unstable plastic deformation region due to dynamic Strain aging was attained.
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anomalies in the deformation mechanism and kinetics of coarse grained high entropy alloy
Materials Science and Engineering A-structural Materials Properties Microstructure and Processing, 2016Co-Authors: Mageshwari Komarasamy, Rajiv S Mishra, Nilesh Kumar, P K LiawAbstract:Abstract Starting from the thermodynamics to thermal and mechanical properties, high entropy alloys (HEAs) always deviate from the behavior of conventional materials and stamp its uniqueness among the alloy systems. In this study, tensile deformation mechanisms of HEA was investigated. A simple system, an Al 0.1 CoCrFeNi HEA, with a single crystal structure (face-centered cubic, FCC), coarser grains (CG), and low dislocation density was chosen to exclusively study the effect of intrinsic lattice on the HEA deformation mechanisms and kinetics. Monotonic tests were done at the Strain Rate of 10 −3 s − 1 , and all the transient tests were started at the Initial Strain Rate of 10 −3 s −1 . Strain-jump tests were carried out at Strain Rates of 10 −5 s −1 and 10 −3 s −1 . Repeated stress relaxation tests were performed along the stress–Strain curve to calculate the physical activation volume. Surprisingly, a large Rate sensitivity of the flow stress and low activation volume of dislocations were observed, which are unparalleled, as compared to conventional CG FCC metals and alloys. The observed trend has been explained in terms of the lattice distortion and dislocation-energy framework. As opposed to the constant dislocation line energy and Peierls potential energy (amplitude, Δ E ) in conventional metals and alloys, both the line energy and Peierls potential undergo continuous variations in the case of HEAs. These energy fluctuations have greatly affected the dislocation mobility and can be distinctly noted from the activation volume of dislocations.
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stress corrosion cracking susceptibility of ultrafine grained al mg sc alloy
Materials Science and Engineering A-structural Materials Properties Microstructure and Processing, 2013Co-Authors: G. R. Argade, Rajiv S Mishra, Nilesh KumarAbstract:Abstract General corrosion and stress corrosion cracking (SCC) behavior of coarse grained, fine grained and ultrafine grained (UFG) AA5083 and Al–Mg–Sc–Zr alloy in different thermomechanical conditions were studied in the present work. Friction stir processing (FSP) was carried out to refine the grain size. The average grain size achieved after FSP for AA5083 was 7±3 μm, whereas that for Al–4Mg–0.8Sc–0.08Zr was 0.39±0.16 μm with 100% UFG microstructure. Linear polarization resistance and cyclic polarization techniques were used to study general corrosion behavior of these alloys in 3.5 wt% NaCl solution. The UFG microstructure showed the highest polarization resistance ( R p ) of ∼93 kΩ which increased to ∼160 kΩ after 24 h of exposure in chloride solution. The peak aged Al–Mg–0.8Sc–0.08Zr showed the most positive breakdown potential with passivity in the range of −800 to −600 mV vs SCE. A power law type relationship was observed between grain size and R p for Al–Mg alloys. SCC susceptibility was estimated in 3.5 wt% NaCl solution using slow Strain Rate testing (SSRT) at Initial Strain Rate of 10 −6 s −1 .The parent AA5083 alloy showed modeRate susceptibility while the FSP AA5083 microstructure showed no susceptibility. The UFG Al–Mg–0.8Sc–0.08Zr condition showed >55% loss in ductility when tested in chloride solution.
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observation of shear thickening during compressive flow of mg54y11ag7cu28 in the supercooled liquid region
Metallurgical and Materials Transactions A-physical Metallurgy and Materials Science, 2009Co-Authors: Neal C Ross, Rajiv S Mishra, O N Senkov, D B MiracleAbstract:Uniaxial compression tests of Mg54Y11Ag7Cu28 metallic glass were performed in the supercooled liquid region (SCLR) (468 K) at a Strain Rate range of 5 × 10−4 to 2 × 10−3 s−1. In the course of testing, shear thickening behavior was observed, where the magnitude of the peak stress increases with increasing Initial Strain Rate. The deformation behavior of the glassy metal is discussed with emphasis on the commonly reported stress overshoot, Strain softening behavior, and the previously unreported shear thickening behavior observed.
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development of ultrafine grained microstructure and low temperature 0 48 tm superplasticity in friction stir processed al mg zr
Scripta Materialia, 2005Co-Authors: Z Y, Rajiv S MishraAbstract:Abstract Friction stir processing (FSP) was applied to extruded Al–4Mg–1Zr to produce fine-grained microstructure with grains sized 0.7–1.6 μm. Low temperature deformation behavior was investigated at 175 °C and Initial Strain Rates of 5 × 10−5–3 × 10−3 s−1. Low temperature superplasticity was observed in ultrafine-grained material. A maximum superplastic elongation of 240% was obtained in ultrafine-grained (0.7 μm) FSP sample at an Initial Strain Rate of 1 × 10−4 s−1 where a maximum Strain Rate sensitivity of 0.34 was observed.
Rustam Kaibyshev - One of the best experts on this subject based on the ideXlab platform.
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superplastic behavior and microstructure evolution in a commercial al mg sc alloy subjected to intense plastic Straining
Metallurgical and Materials Transactions A-physical Metallurgy and Materials Science, 2004Co-Authors: F Musin, Rustam Kaibyshev, Yoshinobu Motohashi, Goroh ItohAbstract:A commercial Al-6 pct Mg-0.3 pct Sc-0.3 pct Mn alloy subjected to equal-channel angular extrusion (ECAE) at 325 °C to a total Strain of about 16 resulted in an average grain size of about 1 µm. Superplastic properties and microstructural evolution of the alloy were studied in tension at Strain Rates ranging from 1.4 × 10−5 to 1.4 s−1 in the temperature interval 250 °C to 500 °C. It was shown that this alloy exhibited superior superplastic properties in the wide temperature range 250 °C to 500 °C at Strain Rates higher than 10−2 s−1. The highest elongation to failure of 2000 pct was attained at a temperature of 450 °C and an Initial Strain Rate of 5.6 × 10−2 s−1 with the corresponding Strain Rate sensitivity coefficient of 0.46. An increase in temperature from 250 °C to 500 °C resulted in a shift of the optimal Strain Rate for superplasticity, at which highest ductility appeared, to higher Strain Rates. Superior superplastic properties of the commercial Al-Mg-Sc alloy are attributed to high stability of ultrafine grain structure under static annealing and superplastic deformation at T ≤ 450 °C. Two different fracture mechanisms were revealed. At temperatures higher than 300 °C or Strain Rates less than 10−1 s−1, failure took place in a brittle manner almost without necking, and cavitation played a major role in the failure. In contrast, at low temperatures or high Strain Rates, fracture occurred in a ductile manner by localized necking. The results suggest that the development of ultrafine-grained structure in the commercial Al-Mg-Sc alloy enables superplastic deformation at high Strain Rates and low temperatures, making the process of superplastic forming commercially attractive for the fabrication of high-volume components.
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superplasticity in a magnesium alloy subjected to isothermal rolling
Scripta Materialia, 2004Co-Authors: A Galiyev, Rustam KaibyshevAbstract:Abstract Superior superplastic ductility of 1330% was achieved at a temperature of 250 °C and an Initial Strain Rate of 1.4 × 10 −4 s −1 in a ZK60 magnesium alloy processed by sequential procedures of extrusion, compression and rolling.
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high Strain Rate superplasticity in a commercial al mg sc alloy
Scripta Materialia, 2004Co-Authors: F Musin, Rustam Kaibyshev, Yoshinobu Motohashi, Goroh ItohAbstract:Abstract It was shown that an Al–5.7%Mg–0.32%Sc–0.3%Mn alloy subjected to severe plastic deformation through equal-channel angular extrusion exhibits superior superplastic properties in the temperature range of 250–500 °C at Strain Rates ranging from 1.4 × 10−5 to 1.4 s−1 with a maximum elongation-to-failure of 2000% recorded at 450 °C and an Initial Strain Rate of 5.6 × 10−2 s−1.
Goroh Itoh - One of the best experts on this subject based on the ideXlab platform.
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superplastic behavior and microstructure evolution in a commercial al mg sc alloy subjected to intense plastic Straining
Metallurgical and Materials Transactions A-physical Metallurgy and Materials Science, 2004Co-Authors: F Musin, Rustam Kaibyshev, Yoshinobu Motohashi, Goroh ItohAbstract:A commercial Al-6 pct Mg-0.3 pct Sc-0.3 pct Mn alloy subjected to equal-channel angular extrusion (ECAE) at 325 °C to a total Strain of about 16 resulted in an average grain size of about 1 µm. Superplastic properties and microstructural evolution of the alloy were studied in tension at Strain Rates ranging from 1.4 × 10−5 to 1.4 s−1 in the temperature interval 250 °C to 500 °C. It was shown that this alloy exhibited superior superplastic properties in the wide temperature range 250 °C to 500 °C at Strain Rates higher than 10−2 s−1. The highest elongation to failure of 2000 pct was attained at a temperature of 450 °C and an Initial Strain Rate of 5.6 × 10−2 s−1 with the corresponding Strain Rate sensitivity coefficient of 0.46. An increase in temperature from 250 °C to 500 °C resulted in a shift of the optimal Strain Rate for superplasticity, at which highest ductility appeared, to higher Strain Rates. Superior superplastic properties of the commercial Al-Mg-Sc alloy are attributed to high stability of ultrafine grain structure under static annealing and superplastic deformation at T ≤ 450 °C. Two different fracture mechanisms were revealed. At temperatures higher than 300 °C or Strain Rates less than 10−1 s−1, failure took place in a brittle manner almost without necking, and cavitation played a major role in the failure. In contrast, at low temperatures or high Strain Rates, fracture occurred in a ductile manner by localized necking. The results suggest that the development of ultrafine-grained structure in the commercial Al-Mg-Sc alloy enables superplastic deformation at high Strain Rates and low temperatures, making the process of superplastic forming commercially attractive for the fabrication of high-volume components.
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high Strain Rate superplasticity in a commercial al mg sc alloy
Scripta Materialia, 2004Co-Authors: F Musin, Rustam Kaibyshev, Yoshinobu Motohashi, Goroh ItohAbstract:Abstract It was shown that an Al–5.7%Mg–0.32%Sc–0.3%Mn alloy subjected to severe plastic deformation through equal-channel angular extrusion exhibits superior superplastic properties in the temperature range of 250–500 °C at Strain Rates ranging from 1.4 × 10−5 to 1.4 s−1 with a maximum elongation-to-failure of 2000% recorded at 450 °C and an Initial Strain Rate of 5.6 × 10−2 s−1.