Structure Dependence of Tensile Creep Behavior in Thermo-Mechanically-Treated Ti-50Mol%Al Intermetallics

1990 ◽  
Vol 213 ◽  
Author(s):  
Tohru Takahashi ◽  
Hiroshi Oikawa
Keyword(s):  
Creep Behavior ◽  
Tensile Creep ◽  
Ingot Metallurgy ◽  
Structural Effects ◽  
Creep Life ◽  
Cast Material ◽  
Creep Properties ◽  
Structure Dependence ◽  
Creep Characteristics

ABSTRACTTensile creep properties have been studied in Ti-50mol%Al intermetallics prepared by ingot metallurgy. Four types of structure were obtained in as-cast material (C), homogenized material (CA), isothermally forged material (F) and forged-and-recrystallized material (FA). Structural effects was investigated by comparing creep properties such as minimum creep rates, fracture strains and creep life among C, CA, F, and FA materials. Creep characteristics were strongly dependent upon the structure.

Improved tensile creep properties of yttrium- and lanthanum-doped alumina: a solid solution effect

2001 ◽  
Vol 16 (2) ◽  
pp. 425-429 ◽  
Author(s):  
Junghyun Cho ◽  
Chong Min Wang ◽  
Helen M. Chan ◽  
J. M. Rickman ◽  
Martin P. Harmer
Keyword(s):  
Solid Solution ◽  
Steady State ◽  
Creep Behavior ◽  
Solubility Limit ◽  
Steady State Creep ◽  
Tensile Creep ◽  
Creep Properties ◽  
Uniform Microstructure ◽  
Equiaxed Grains ◽  
Rare Earth Doped

The tensile creep behavior of yttrium- and lanthanum-doped alumina (at dopant levels below the solubility limit) was examined. Both compositions (100 ppm yttrium, 100 ppm lanthanum) exhibited a uniform microstructure consisting of fine, equiaxed grains. The creep resistance of both doped aluminas was enhanced, compared with undoped alumina, by about two orders of magnitude, which was almost the same degree of improvement as for materials with higher dopant levels (in excess of the solubility limit). In addition, measured creep rupture curves exhibited predominantly steady-state creep behavior. Our results, therefore, verified that the creep improvement in these rare-earth doped aluminas was primarily a solid-solution effect.

scholarly journals Tensile Creep Properties of Cr-Si Alloys at 980 °C in Air—Influence of Ge and Mo Addition

Metals ◽  
2021 ◽  
Vol 11 (7) ◽  
pp. 1072
Author(s):  
Petra Pfizenmaier ◽  
Anke Silvia Ulrich ◽  
Mathias C. Galetz ◽  
Uwe Glatzel
Keyword(s):  
Creep Behavior ◽  
Alloy Composition ◽  
Constant Load ◽  
Ternary Alloys ◽  
Tensile Creep ◽  
Chromium Nitride ◽  
Creep Properties ◽  
Alloying Additions ◽  
Nitride Formation ◽  
The Impact

The tensile creep behavior of Cr-Si alloys with Cr ≥ 91 at.% was investigated in air at 980 °C with a constant load of 50–100 MPa. Additionally, the influence of substitutional alloying additions of 2 at.% Ge and Mo, leading to ternary alloys was studied. The addition of Ge or Mo results in an improvement in creep strength, with the highest strength achieved with addition of Mo. For longer creep exposure times a strong effect is observed, because of severe nitrogen uptake from the air, depending on alloy composition. Based on the results a novel mechanism for the impact of chromium nitride formation on the creep behavior is proposed.

A Physically Consistent Method for the Prediction of Creep Behavior of Metals

1979 ◽  
Vol 46 (4) ◽  
pp. 800-804 ◽  
Author(s):  
G. J. Weng
Keyword(s):  
Single Crystals ◽  
Creep Behavior ◽  
Pure Shear ◽  
Tensile Creep ◽  
Polycrystalline Materials ◽  
Steady Creep ◽  
Creep Properties ◽  
Consistent Method ◽  
Latent Hardening ◽  
Good Agreement

A physically consistent method, which considers the deformation mechanisms, the active and latent hardening in single crystals, and their transient and steady creep, is proposed to predict the creep behavior of polycrystalline materials. This method consists of two steps: first, the material constants of single crystals are determined from the tensile creep data of the polycrystal, and then these constants are used to predict the creep properties of the same polycrystal under required loading conditions. This method simultaneously satisfies the requirements of equilibrium and compatibility over the grain boundaries, and is self-consistent. The proposed method was applied to calculate the creep strains of a 2618-T61 Aluminum alloy under pure shear, combined stress and nonradial loading; the results obtained were in good agreement with the test data.

The Effect of Molybdenum on the Creep Behavior of Orthorhombic Titanium Aluminides

2002 ◽  
Author(s):  
Dominique A. Shepherd ◽  
Vijay K. Vasudevan
Keyword(s):  
Creep Behavior ◽  
Titanium Aluminide ◽  
Creep Resistance ◽  
Titanium Aluminides ◽  
Tensile Creep ◽  
Atomic Fraction ◽  
Beta Transus ◽  
Creep Properties ◽  
Orthorhombic Titanium ◽  
Transus Temperature

The effect of molybdenum additions on the creep properties of two orthorhombic titanium aluminide materials, Ti-22Al-26Nb and Ti-22Al-24.5Nb-1.5Mo (% atomic fraction), has been investigated. Heat treatments below the beta transus temperature followed by a 16-hour ageing treatment produced similar microstructures. Using the similar microstructures (consisting of O laths in a B2 matrix with α2 dispersed at B2 grain boundaries) for the two compositions, tensile creep testing was conducted under stresses of 68 MPa, 160 MPa, and 197 MPa at temperatures of 590 °C and 760 °C. The creep results demonstrated the favorable effects of Mo on creep resistance in these orthorhombic titanium aluminides. Due to similar microstructures, results also suggested that improvements have been substructural, rather than purely microstructural, in nature.

Microstructures and Creep Behavior of As-Cast TiAl-Nb Alloy

2015 ◽  
Vol 816 ◽  
pp. 572-577 ◽  
Author(s):  
Su Gui Tian ◽  
Xiao Xia Wu ◽  
Hui Chen Yu ◽  
Hao Fang Sun ◽  
Ze Hui Jiao
Keyword(s):  
High Temperature ◽  
Crack Propagation ◽  
Creep Behavior ◽  
Creep Resistance ◽  
Stress Axis ◽  
Creep Life ◽  
Creep Properties ◽  
Creep Fracture ◽  
Microstructure Observation

By means of creep properties measurement and microstructure observation, an investigation was carried out to study the creep behaviors of the as-cast TiAl-Nb alloy at temperature near 910 oC. Results showed that the microstructure of as-cast TiAl-Nb alloy consisted of γ/α2 phases with the lamellar feature, and the boundaries with irregular serrated configuration consisted of single γ phase, and located in between the lamellar γ/α2 phases with different orientations. The as-cast TiAl-Nb alloy displayed a better creep resistance at high temperature and longer creep life. Compared to α2 -Ti3Al phase, the γ phase possessed a weaker strength, therefore, the crack was easily initiated along the boundaries at about 45° angles relative to the stress axis, and propagated along the boundaries parallel to the orientation of lamellar γ/α2 phases up to the occurrence of creep fracture. Thereinto, the tearing edges formed on the surface of the fracture being inclined with the lamellar γ/α2 phases are attributed to the α2-Ti3Al phase with better strength hindering the crack propagation during creep.

scholarly journals Study on Characterization of Compressive and Tensile Creep Behavior for Early Aged Concrete.

1998 ◽  
pp. 105-117
Author(s):  
Keishiro Iriya ◽  
Tatsuya Hattori ◽  
Hidetaka Umehara
Keyword(s):  
Creep Behavior ◽  
Tensile Creep

Creep Life Simulation and Assessment of High Temperature Piping Systems and Components

2012 ◽  
Author(s):  
Brian Rose ◽  
James Widrig
Keyword(s):  
Finite Element Analysis ◽  
Finite Element ◽  
High Temperature ◽  
Creep Behavior ◽  
Material Behavior ◽  
Piping System ◽  
Remaining Life ◽  
Creep Life ◽  
Element Analysis ◽  
Piping Systems

High temperature piping systems and associated components, elbows and bellows in particular, are vulnerable to damage from creep. The creep behavior of the system is simulated using finite element analysis (FEA). Material behavior and damage is characterized using the MPC Omega law, which captures creep embrittlement. Elbow elements provide rapid yet accurate modeling of pinching of piping, which consumes a major portion of the creep life. The simulation is used to estimate the remaining life of the piping system, evaluate the adequacy of existing bellows and spring can supports and explore remediation options.

Sign in / Sign up

Export Citation Format

Share Document