Evolution and microstructural characteristics of deformation bands in fatigued copper single crystals

Zhang, Z. F.; Wang, Z. G.; Sun, ZhengMing

doi:10.1016/s1359-6454(01)00219-1

Cited by 70 publications

(36 citation statements)

References 39 publications

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“…The TB poses great barrier to the dislocation motion in this case 20 and with the cyclic deformation, the strain gradually concentrates in the grain interior. Thus it is observed that the fatigue cracks nucleate along the densely distributed SBs in the grain interior on one side of the TB as that found in single crystal 26,27 ; in addition, there are already some fatal fatigue cracks formed along the SBs in areas close to the transition area of the specimen. As shown in Fig.…”

Section: Sem and Ecc Results Of Bicrystal With A Perpendicular Tbmentioning

confidence: 73%

“…It is about 3 Â 10 4 cycles at which the fatigue crack was observed in the bicrystal with a TB perpendicular to the loading direction. The resolved shear stress of the bicrystal with a perpendicular TB increased monotonously with increasing cyclic number without saturation phenomenon as that in a cyclically deformed o1114 copper single crystal 27,30 . Thus the nominal resolved shear stress amplitude has been raised to about 48 MPa until the fatigue cracks were detected.…”

Section: Methodsmentioning

confidence: 81%

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Controllable fatigue cracking mechanisms of copper bicrystals with a coherent twin boundary

Zhang

et al. 2014

Nat Commun

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Section: Sem and Ecc Results Of Bicrystal With A Perpendicular Tbmentioning

confidence: 73%

Section: Methodsmentioning

confidence: 81%

Controllable fatigue cracking mechanisms of copper bicrystals with a coherent twin boundary

Zhang

et al. 2014

Nat Commun

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“…Such a non-uniform distribution of hardness due to the underlying non-uniform substructures has been known in cyclically deformed copper crystals, in which the cyclically saturated microstructure of copper is composed of a hard matrix (essentially vein dislocation structure) and a soft permanent slip band (ladderlike dislocation structures), with plastic deformation mainly localized within the permanent slip band. 9) A good understanding of the non-uniform distribution of microstructure and hardness in deformed Hadfield steel is of critical significance, since damage and cracking tends to be initiated at local severely strained regions because of the mismatch of deformation, as was reported in cyclically deformed copper where crack tends to be initiated at the boundary of the permanent slip band and matrix. 9,10) Further work is currently being undertaken to investigate crack initiation and the incompatibility of deformation owing to the non-uniform hardness distribution in the deformed Hadfield steel by means of in situ SEM observation and crystal plasticity finite element method.…”

Section: Deformed Microstructurementioning

confidence: 99%

“…9,10) Some researchers have, indeed, evaluated the degree of straining heterogeneity due to mechanical twinning of Hadfield steel by a digital image correlation method; 8) however, not much attention has been paid to the local-scale hardness in deformed Hadfield steel. A non-uniform distribution of hardness on the local scale, which may be influenced by a number of factors such as grain boundary, grain orientation of the indentation plane as well as the microstructures under the indentation tip, [11][12][13] can be expected in the deformed Hadfield steel.…”

Section: Introductionmentioning

confidence: 99%

Deformed Microstructure and Hardness of Hadfield High Manganese Steel

2011

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The distribution of micro/nano-indentation hardness and microstructures of deformed Hadfield high manganese steel have been investigated by means of micro/nano-indentation tests, and optical and electron microscopic observations. Indentation tests demonstrated that there exists a very non-uniform distribution of hardness, with a hardness variation of $30% in different grains and in different regions of the same grain. Microscopic observations indicated that the large non-uniformity of micro/nano-hardness is caused mainly by the underlying nonhomogeneous substructures (twins, dislocations, etc.), which are closely associated with the non-uniform work hardening in the deformed Hadfield steel, while the effects of the austenite grain boundary and the grain orientation of the indentation plane are not significant.

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“…By using ECCI technique crystallographic defects, which produces a distortion in the lattice, such as dislocation or substructure, twins, stacking faults and grain boundaries are possible to observe (see figure 16). ECCI technique produces images that are similar in appearance to transmission electron micrographs, however, with lower resolution [41]. The reason to use accelerating voltages below the commonly used value of 20 kV is that with decreasing voltage the cross section for phonon scattering is increased, which led to that bright parts in the image, i.e.…”

Section: Electron Channeling Contrast Imaging (Ecci) Techniquementioning

confidence: 99%

Influence of deformation and environmental degradation of Inconel 792

Kanesund¹

2017

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Industrial gas turbines are often used as a mechanical drive for pumps and compressors or in power generation as an electric power supply. The gas turbine has for many years been a popular engine due to its flexibility with respect to different types of fuel and due to a design, that enables a high power-to-weight ratio. A simplified description of a gas turbine is that the engine consists of a cold and hot section. The turbo compressor section belongs to cold section and the combustion chamber together with the turbine section belongs to the hot section. In the hot section of a gas turbine, the condition is extremely severe because of an aggressive environment characterized by high temperatures, increased temperature gradients, high pressure and centrifugal forces resulting in large stresses on individual components together with an oxidizing and corroding atmosphere. Materials used in the high temperature section (hot gas path) of a modern gas turbine are different types of superalloys, as single crystal, directionally solidified or polycrystalline alloys, depending on temperature and load conditions. In the first turbine stage, temperature is very high due to exposure to the combustion gas. To handle the problem with creep, single crystal superalloys are often used in this section. In the second row of turbine blades, the temperature of the gas is lower and polycrystalline superalloys are typically used. IN-792 is a cast polycrystalline superalloy with high strength, good resistance to hot corrosion and a cheaper option than single crystals. In the hot section of gas turbine, IN-792 is a suitable material for components such as turbine blades and vans where a complex load condition, high temperature and severe environment prevails. Due to startup and shutdown of the gas turbine engine during service, the components in the hot section are exposed to cyclic load and temperature. This will generate mechanical and thermal fatigue damage in gas turbine components. Steady state temperature gradient arises by the cooling system acting at cold spots during service to introduce tensile stress, which indirectly gives rise to creep damage in the component. This work includes tree studies of deformation and damage mechanisms of superalloy IN-792. The first study is made on test bars exposed to thermomechanical fatigue in laboratory environment, the second and the third study is made on turbine blades used during service. In the second study, the machines are placed off-shore and exposed to marine environment. In the third study the machine is landbased and exposed to an industrial environment. In the second study, the deformation and damage mechanisms are compared between the turbine blades used during service and the test bars exposed to thermomechanical fatigue testing in the first study.v

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Evolution and microstructural characteristics of deformation bands in fatigued copper single crystals

Cited by 70 publications

References 39 publications

Controllable fatigue cracking mechanisms of copper bicrystals with a coherent twin boundary

Controllable fatigue cracking mechanisms of copper bicrystals with a coherent twin boundary

Deformed Microstructure and Hardness of Hadfield High Manganese Steel

Influence of deformation and environmental degradation of Inconel 792

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