Steady-state creep of single-phase crystalline matter at high temperature

Takeuchi, Shin; Argon, A. S.

doi:10.1007/bf00540888

Cited by 501 publications

(145 citation statements)

References 153 publications

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“…36) In the case of single phase materials, an analysis of many sets of data shows the similar relation with a constant of about 20. 37) This means that the average subgrain size of a Mod.9Cr-1Mo steel is close to that of single phase materials when crept to rupture at a stress above 137 MPa ('=G ¼ 2:19 Â 10 À3 ). In contrast to data points obtained above 137 MPa, the subgrain size obtained at 100 MPa is somewhat different in behavior.…”

Section: Non-homogenious Recovery Of Lath Structuresmentioning

confidence: 87%

Change in Vickers Hardness and Substructure during Creep of a Mod.9Cr-1Mo Steel

2003

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In order to investigate the structural degradation during creep, interrupted creep tests were conducted of a Mod.9Cr-1Mo steel in the range of stress and temperature from 71 to 167 MPa and 873 to 923 K. The change of hardness and tempered martensitic lath width were measured in grip and gauge parts of interrupted specimens. The lath structure was thermally stable in static conditions, however, it was not stable during creep and the structural change was enhanced by creep strain. The relation between the change in lath width and strain was described quantitatively. The change in Vickers hardness was expressed by a single valued function of creep life consumption ratio. Based on the empirical relation between strain and lath width, a model was proposed to describe the relation between change in hardness and creep life consumption ratio. The comparison of the model with the empirical relation suggests that about 65% of hardness loss is due to the decrease of dislocation density accompanied by the movement of lath boundaries. The role of precipitates on subboundaries was discussed in connection with the abnormal subgrain growth appearing in low stress regime.

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Section: Non-homogenious Recovery Of Lath Structuresmentioning

confidence: 87%

Change in Vickers Hardness and Substructure during Creep of a Mod.9Cr-1Mo Steel

2003

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“…In the following discussion, it is assumed that this transition is equivalent to the progressive development of the most highly strained microstructures. Stages (i)-(iii) of the microstructural transition described above are typical of the hardening stage that most materials undergo at high temperature, prior to steady state deformation (McQueen and Jonas, 1975;Takeuchi and Argon, 1976;White, 1977). The initial rapid increase in dislocation density gives rise to the high primary creep rate (or the microstrain interval of hot working described by McQueen and Jonas, 1975), but the resulting dislocation interactions lead to subsequent hardening.…”

Section: Discussionmentioning

confidence: 97%

Dynamic Recrystallization in a Naturally Deformed Albite

Gerald

Etheridge

Vernon

1982

Texture, Stress, and Microstructure

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Coarse-grained, deformed albite occurs in veins within a blueschist from the Cazadero region, California. In some grains, deformation and recrystallization are concentrated in narrow shear zones less than 50/m wide. We have examined the substructural progression across these zones by transmission electron microscopy (TEM), in an attempt to determine the details ofthe dynamic recrystallization mechanism. The misorientation across subgrain and recrystallized grain boundaries has been determined by analysis of electron diffraction patterns.Dynamic recrystallization apparently proceeded by the following stages: 1) the formation of a well-ordered substructure from a more tangled, cell-like array, 2) increasing misorientation between subgrains, 3) rapid growth of subgrains at a misorientation between 3 and 5 to produce new "'grains" with straighter grain boundaries and lower internal dislocation densities and 4) continued deformation and rotation of the recrystallized grains with local grain-boundary migration to maintain relatively equiaxed shapes. The ultimate recrystallized structure in the narrow deformation zones consists of grains misoriented by between 5 and at least 30 , most of them containing a well-developed substructure.The combination of subgrain growth and rotation explains a number of features common to dynamically recrystallized minerals. The smaller subgrains present prior to growth and also within recrystallized grains form a population distinct from the larger subgrains and recrystallized grains ofapproximately equal size, which are those observed in an optical microscope. The smaller subgrains are visible only in TEM. Individual recrystallized grains may .remain through substantial straining, rotating in response to dislocation and sub-boundary motion within them, thus preserving and even enhancing the crystallographic fabric (texture). The retention of an initial recrystallized grain population throughout significant continuing deformation may explain the absence of strain softening in some recent experimental studies.

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“…For Al, a is reported to be 0. 7,6) and the work hardening rate and the shear modulus extrapolated to 0 K are reported to be 85 MPa 7) and 28 GPa, 8) respectively.…”

Section: Modelingmentioning

confidence: 97%