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Journal ArticleDOI

Processing maps for hot deformation of α2 aluminide alloy Ti-24Al-11Nb

01 Mar 2002-Journal of Materials Science (Kluwer Academic Publishers)-Vol. 37, Iss: 6, pp 1197-1201
TL;DR: Using the test data of α2 titanium aluminide alloy Ti-24Al-11Nb with microstructural observations, studies were made to examine the flow localization concepts as well as the simplified metallurgical stability criterion for delineating the regions of flow instabilities in the processing maps.
Abstract: Using the test data of α2 titanium aluminide alloy Ti-24Al-11Nb with microstructural observations, studies are made to examine the flow localization concepts as well as the simplified metallurgical stability criterion for delineating the regions of flow instabilities in the processing maps. The optimum hot working conditions for the material are suggested.
Citations
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Journal ArticleDOI
TL;DR: In this paper, the hot deformation characteristics of 7075 aluminum alloy (AA7075) were investigated by means of hot compression tests carried out in the temperature range of 200-450°C and strain rate range of 0.0003-1-s−1.

63 citations

Journal ArticleDOI
TL;DR: In this paper, a hot isothermal compression test is carried out on reaction synthesized and homogenized titanium aluminide alloys at different temperatures and strain rates using Gleeble thermomechanical simulator.
Abstract: Gamma titanium alumindes are intermetallics, which have very narrow working range. Hot isothermal working is the most suitable process for hot working of alloy. Accordingly, hot isothermal compression test is carried out on reaction synthesized and homogenized titanium aluminide alloys at different temperatures and strain rates using Gleeble thermomechanical simulator. Three alloys of Ti48Al2Cr2Nb0.1B (atom%) have been used in the study. Stress–strain data obtained from the test has been used to construct processing map, which indicates the safe and unsafe working zone. Strain rate sensitivity and Zener–Hollomon parameter has been calculated. Further, constitutive equations have been generated and verified. It is found that alloy has good workability in the temperature range of 1223–1423 K at strain rates of 0.01–0.001 s −1 . In this range of parameters, the alloys nearly follow the constitutive equations.

43 citations

Journal ArticleDOI
TL;DR: In this article, a processing map of Aermet100 steel was developed based on a simple instability condition applicable to a general flow stress versus strain rate curve at any strain and temperature.
Abstract: Using the flow stress data obtained from the compression tests in the temperature ranges of 800–1200 °C and at strain rate ranges of 0.01–50 s −1 , the processing map of Aermet100 steel was developed based on a simple instability condition applicable to a general flow stress versus strain rate curve at any strain and temperature. Deformation mechanisms in the stable and unstable regimes were verified with the microstructure observations. The optimum hot processing windows of Aermet100 steel are at temperature ranges of 1025–1200 °C and at strain rate ranges of 0.03–15 s −1 , in which dynamic recrystallization occurs with a peak efficiency of power dissipation of 38%. The instability regimes I and II occur at low temperature ranges of 800–975 °C, and at strain rate ranges of 0.1–6 s −1 and 4.5–33 s −1 , respectively. While the instability regime III occurs at high temperature ranges of 950–1200 °C and at high strain rate ranges of 15–50 s −1 . These instability regimes, whose microstructural manifestations such as cracks, shear bands and twin kink bands are detrimental to the mechanical properties of components, need to be avoided during hot processing of Aermet100 steel.

32 citations

Journal ArticleDOI
Daosheng Wen1, Youhai Zong1, Yi Wang, Z.Y. Liu1, Debin Shan1 
TL;DR: In this paper, high temperature deformation behaviors of the unhydrogenated and hydrogenated Ti-46Al-2V-1Cr-0.3Ni alloys were investigated in the temperature range 1050-1200 ǫ c and strain rate range 0.001-1 s−1.
Abstract: High temperature deformation behaviors of the unhydrogenated and hydrogenated Ti-46Al-2V-1Cr-0.3Ni (at%) alloys were investigated in the temperature range 1050–1200 °C and strain rate range 0.001–1 s−1. The flow stress of the hydrogenated alloy was lower than that of the unhydrogenated alloy, which was mainly attributed to hydrogen-promoted lamellar decomposition, twinning and dynamic recrystallization. Processing maps of the unhydrogenated and hydrogenated alloys were constructed. The stability domain of the hydrogenated alloy was enlarged in comparison with that of the unhydrogenated alloy, meaning hydrogen enhanced the hot workability of the Ti-46Al-2V-1Cr-0.3Ni alloy. Hydrogen activated slip systems so that lamellar bending more easily occurred in the hydrogenated alloy, which made inter-lamellar fracture convert into trans-lamellar fracture. Therefore, crack propagation was restrained in the hydrogenated alloy during hot deformation. The critical strain of the hydrogenated alloy was less than those of the unhydrogenated alloy, meaning the dynamic recrystallization occurred earlier in the hydrogenated alloy. γ-phase discontinuous dynamic recrystallization was promoted due to hydrogen addition, leading to a consumption of plentiful dislocations, which restrained continuous dynamic recrystallization to some extent. Hydrogen-promoted discontinuous dynamic recrystallization was mainly attributed to hydrogen-promoted lamellar decomposition, twinning, and hydrogen-decreased stacking fault energy.

25 citations

Journal ArticleDOI
TL;DR: In this paper, the phase relations and ternary solubility of the binary compounds were determined using electron probe microscopy (EPMA), wave dispersive X-ray spectrometer (WDS), and XRD techniques.

22 citations

References
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01 Jan 1985
TL;DR: In this article, the authors describe the behavior of grain boundaries in a two-dimensional model ordered alloy and the effects of elastic anisotropy on the anomalious yield behavior of cubic ordered alloys.
Abstract: This book contains over 50 selections. Some of the titles are: Order-disorder behavior of grain boundaries in a two-dimensional model ordered alloy; Dislocation reactions at grain boundaries in Ll/sub 2/ ordered alloys; Creep cavitation in a nickel aluminide; Effects of elastic anisotropy on the anomalious yield behavior of cubic ordered alloys; and Processing technology for nickel aluminides.

2,123 citations

Book
01 Jan 1963

1,040 citations

Journal ArticleDOI
TL;DR: In this paper, a simple condition for metallurgical instability, useful in the development of processing maps for analysing high-temperature forming of metals, is suggested following a criterion based on continuum principles as applied to large plastic flow proposed by Ziegler.
Abstract: A simple condition for metallurgical instability, useful in the development of processing maps for analysing high-temperature forming of metals, is suggested following a criterion based on continuum principles as applied to large plastic flow proposed by Ziegler. It can be used for any type of flow stress versus strain rate curve. This criterion has been validated using the flow stress data of a 6061 Al-10 vol% metal matrix composite with microstructural observations. Optimum hot working conditions based on the instability map are suggested for this material.

35 citations