Hardening behavior of three metallic alloys under combined stresses at elevated temperature

Lissenden, Cliff J.; Colaiuta, J. F.; Lerch, Bradley A.

doi:10.1007/s00707-004-0092-3

Cited by 12 publications

(4 citation statements)

References 26 publications

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“…It has exhibited good fabricability, tensile strength and elongation-to-failure, weldability, low-cycle fatigue resistance, and corrosion resistance. [1][2][3][4][5][6] It has useful applications in gas turbines, combustors, flame holders, liners, and transition ducts. A complete understanding of the physical mechanisms responsible for the elevated-temperature creep behavior and associated microstructure-property relationships of Udimet 188 is lacking.…”

Section: Introductionmentioning

confidence: 99%

The evolution of grain-boundary cracking evaluated through in situ tensile-creep testing of Udimet alloy 188

et al. 2008

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In situ scanning electron microscopy was performed during elevated-temperature (ഛ760°C) tensile-creep deformation of a face-centered-cubic cobalt-based Udimet 188 alloy to characterize the deformation evolution and, in particular, the grain boundary-cracking evolution. In situ electron backscatter diffraction observations combined with in situ secondary electron imaging indicated that general high-angle grain boundaries were more susceptible to cracking than low-angle grain boundaries and coincident site-lattice boundaries. The extent of general high-angle grain-boundary cracking increased with increasing creep time. Grain-boundary cracking was also observed throughout subsurface locations as observed for postdeformed samples. The electron backscattered diffraction orientation mapping performed during in situ tensile-creep deformation proved to be a powerful means for characterizing the surface deformation evolution and in particular for quantifying the types of grain boundaries that preferentially cracked.

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Section: Introductionmentioning

confidence: 99%

The evolution of grain-boundary cracking evaluated through in situ tensile-creep testing of Udimet alloy 188

et al. 2008

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“…It exhibits good fabricability and an attractive balance of tensile properties and creep and oxidation resistance up to 1,366 K~1, 0938C!~Herchenroeder et al, 1972;Whittenberger, 1992Whittenberger, , 1994Chen et al, 2001;Zhu et al, 2002;Lissenden et al, 2004!. Due to its attractive properties, it is used in gas turbines, combustors, flame holders, liners, and transition ducts. is a commercially available cobalt-based superalloy containing nickel, chromium, and tungsten as its primary alloying elements.…”

Section: Introductionmentioning

confidence: 99%

“…Udimet 188 (also known as Haynes Alloy 188 and UD 188) is a commercially available cobalt-based superalloy containing nickel, chromium, and tungsten as its primary alloying elements. It exhibits good fabricability and an attractive balance of tensile properties and creep and oxidation resistance up to 1,366 K (1,093°C) (Herchenroeder et al, 1972; Whittenberger, 1992, 1994; Chen et al, 2001; Zhu et al, 2002; Lissenden et al, 2004). Due to its attractive properties, it is used in gas turbines, combustors, flame holders, liners, and transition ducts.…”

Section: Introductionmentioning

confidence: 99%

The Microstructure and Creep Behavior of Cold Rolled Udimet 188 Sheet

Boehlert

Longanbach

2010

Microsc Microanal

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Udimet 188 was subjected to thermomechanical processing (TMP) in an attempt to understand the effects of cold-rolling deformation on the microstructure and tensile-creep behavior. Commercially available sheet was cold rolled to varying amounts of deformation (between 5-35% reduction in sheet thickness) followed by a solution treatment at 1,464 K (1,191 °C) for 1 h and subsequent air cooling. This sequence was repeated four times to induce a high-volume fraction of low-energy grain boundaries. The resultant microstructure was characterized using electron backscattered diffraction. The effect of the TMP treatment on the high-temperature [1,033-1,088 K (760-815 °C)] creep behavior was evaluated. The measured creep stress exponents (6.0-6.8) suggested that dislocation creep was dominant at 1,033 K (760 °C) for stresses ranging between 100-220 MPa. For stresses ranging between 25-100 MPa at 1,033 K (760 °C), the stress exponents (2.3-2.8) suggested grain boundary sliding was dominant. A significant amount of grain boundary cracking was observed both on the surface and subsurface of deformed samples. To assess the mechanisms of crack nucleation, in situ scanning electron microscopy was performed during the elevated-temperature tensile-creep deformation. Cracking occurred preferentially along general high-angle grain boundaries (GHAB) and less than 25% of the cracks were found on low-angle grain boundaries (LAB) and coincident site lattice boundaries (CSLB). Creep rupture experiments were performed at T = 1,088 K (815 °C) and σ = 165 MPa and the greatest average time-to-rupture was exhibited by the TMP sheet with the greatest fraction of LAB+CSLB. However, a clear correlation was not exhibited between the grain boundary character distribution and the minimum creep rates. The findings of this work suggest that although grain boundary engineering may be possible for this alloy, simply relating the fraction of grain boundary types to the creep resistance is not sufficient.

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“…188) is a commercially available cobalt-nickel-chromium-tungsten alloy with good creep strength and oxidation resistance up to 1093ºC. The alloy also has good fabricability, tensile strength and elongation-to-failure (ε f ), weldability, low-cycle fatigue resistance, and corrosion resistance [1][2][3][4][5][6]. Despite its use in gas turbines, combustors, flame holders, liners, and transition ducts, only a limited number of studies have examined how processing affects the microstructure and creep behavior of Udimet alloy 188 [4,5,7,8].…”

Section: Introductionmentioning

confidence: 99%

The Effect of Thermomechanical Processing on the Microstructure and Creep Behavior of Udimet Alloy 188

Longanbach

Boehlert²

2008

Superalloys 2008 (Eleventh International Symposium)

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Udimet 188 alloy was subjected to thermomechanical processing in attempt to understand the effects of cold-rolling deformation on the microstructure and tensile-creep behavior. Commercially available sheet was cold rolled to varying amounts of deformation (between 5%-35% reduction in sheet thickness) followed by a solution treatment at 1191ºC for one hour followed by air cooling. This sequence was repeated four times to induce a favorable grain boundary character distribution containing a high volume fraction of low-energy grain boundaries. The resultant microstructure was characterized using electron backscattered diffraction. The effect of the thermomechanical processing treatment on the hightemperature (760-815ºC) creep behavior was evaluated. Conventional lever-arm creep experiments were performed in an open air environment. The measured creep stress exponents (5.7-6.4) suggested that dislocation creep was dominant at 760ºC for stresses ranging between 100-220MPa. The material exhibited a significant extent of grain boundary cracking. The thermomechanical processing treatments which resulted in the greatest fractions (~0.8) of special grain boundaries (low-angle boundaries + coincident site lattice boundaries) also exhibited the lowest creep rates. Thus a correlation was exhibited between the grain boundary character distribution and the minimum creep rates. Creep rupture experiments were performed at T=815ºC and σ=165MPa and the thermomechanical processing treatment which resulted in the greatest special boundary fraction also resulted in the greatest average time-to-rupture.

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Hardening behavior of three metallic alloys under combined stresses at elevated temperature

Cited by 12 publications

References 26 publications

The evolution of grain-boundary cracking evaluated through in situ tensile-creep testing of Udimet alloy 188

The evolution of grain-boundary cracking evaluated through in situ tensile-creep testing of Udimet alloy 188

The Microstructure and Creep Behavior of Cold Rolled Udimet 188 Sheet

The Effect of Thermomechanical Processing on the Microstructure and Creep Behavior of Udimet Alloy 188

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