A model of continuous dynamic recrystallization

Gourdet, Sophie; Montheillet, F.

doi:10.1016/s1359-6454(03)00078-8

Cited by 726 publications

(295 citation statements)

References 18 publications

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“…Based on previous studies, it can be inferred that HPT processing causes an increase in the tensile strength owing to grain re nement, and an increase in volume fraction of the ε phase and in dislocation density. 14,[31][32][33][34][35] The UTS and 0.2% proof stress of CCM HPTA(1073 K,0.3 ks) are lower than to those of the CCM HPT . CCM HPTA(1073 K,0.3 ks) exhibits an excessive volume fraction of the ε phase and does not show an ultra ne-grained microstructure, which causes a lower elongation compared to CCM HPTA(1273 K,0.3 ks) and CCM HPTA(1473 K,0.3 ks) .…”

Section: Optimization Of Short Annealing Temperaturementioning

confidence: 88%

Optimization of Microstructure and Mechanical Properties of Co–Cr–Mo Alloys by High-Pressure Torsion and Subsequent Short Annealing

et al. 2016

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The main target of this study is to optimize the microstructure and to achieve an optimization for the mechanical properties in a biomedical Co-Cr-Mo (CCM) alloy with the nominal composition of Co-28Cr-6Mo (mass%) subjected to high-pressure torsion (HPT) and subsequent short annealing. The γ → ε phase transformation and grain re nement occur in the CCM alloy subjected to HPT processing at an equivalent strain (ε eq ) of 2.25 (CCM HPT ). The HPT processing causes a decrease in the elongation due to the formation of an excessive amount of ε phase. For removal of the excessive amount of ε phases, the CCM HPT was subjected to a short annealing (CCM HPTA ). The effect of the short annealing temperature (1073 K, 1273 K, and 1473 K; annealing time was xed at 0.3 ks) on CCM HPT was investigated. In addition, the effect of the length of duration for the short annealing (0.06 ks, 0.3 ks, and 0.6 ks;) for a xed annealing temperature of 1273 K on CCM HPT was studied. CCM HPTA(1273 K) annealed for 0.3 ks shows a good optimization of mechanical properties that include high strength and large elongation owing to its ultra ne-grained microstructure, and removal of excessive ε phases.

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Section: Optimization Of Short Annealing Temperaturementioning

confidence: 88%

Optimization of Microstructure and Mechanical Properties of Co–Cr–Mo Alloys by High-Pressure Torsion and Subsequent Short Annealing

et al. 2016

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“…The formation of fine and ultrafine ferrite grains in these zones can be due to the continuous dynamic recrystallisation caused by substantial levels of shear deformation and the heat induced by the FSW process. The continuous dynamic recrystallisation occurs due to the progressive formation of low angle grain boundaries (LAGBs) within the grains subjected to sever plastic deformation, and the eventual conversion of these LAGBs to high angle grain boundaries (HAGBs) upon reaching a critical misorientation angle [42]. Previous studies have reported the formation of ultra-fine ferrite (< 3 µm) under high levels of shear strains and undercooling, through a single hot rolling pass applied to hypoeutectoid steels [43][44].…”

Section: Equationmentioning

confidence: 99%

Development of Microstructure and Crystallographic Texture in a Double-Sided Friction Stir Welded Microalloyed Steel

Rahimi

Wynne

Baker

2016

Metall Mater Trans A

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The evolution of microstructure and crystallographic texture has been investigated in double-sided friction stir welded microalloyed steel, using electron backscatter diffraction (EBSD). The microstructure analyses show that the centre of stirred zone reached a temperature between Ac 1 -Ac 3 during FSW, resulting in a dual phase austenitic/ ferritic microstructure. The temperatures in the thermo-mechanically affected zone and the overlapped area between the first and second weld pass did not exceed the Ac 1 . The shear generated by the rotation probe occurs in austenitic/ferritic phase field where the austenite portion of the microstructure is transformed to a bainitic ferrite, on cooling. Analysis of crystallographic textures with regard to shear flow lines generated by the probe tool, show the dominance of simple shear components across the whole weld. The austenite texture at Ac 1 -Ac 3 is dominated by the B and simple shear texture components, where the bainite phase textures formed on cooling were inherited from the shear textures of the austenite phase with relatively strong variant selection. The ferrite portion of the stirred zone and the ferrites in the thermo-mechanically affected zones and the overlapped area underwent shear deformation with textures dominated by the D 1 and D 2 simple shear texture components. The formation of ultra-fine equiaxed ferrite with submicron grain size has been observed in the overlapped area between the first and second weld pass. This is due to continuous dynamic strain-induced recrystallisation as a result of simultaneous severe shear deformation and drastic undercooling.

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“…For sample A the curve is characterized by a peak stress at low shear strain followed by strain softening towards a steady state shear stress above a shear strain of about 3. This behaviour is typical for materials exhibiting dynamic recrystallization (DRX) [13,14]. During DRX the lamellar structure (colony size about 100μm) breaks down and grain refinement takes place resulting in a steady state equiaxed γ grain structure with a grain size of about 2 µm (Fig.…”

Section: Resultsmentioning

confidence: 92%

High strain torsion of a TiAl-based alloy

Cao

Klöden

Rybacki

et al. 2008

Materials Science and Engineering: A

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A two-phase lamellar and globular TiAl-based alloy Nb, Ta, B)) with different textures has been deformed in torsion in a Paterson-type rock deformation machine at a temperature of 1173 K under 400 MPa argon confining pressure. The shear stress -shear strain curves with increasing shear strain show a decrease or increase of shear stress in the lamellar and globular case, respectively, to a common steady state value. Activation analysis at high strains yields stress exponents of about 1.8 and an activation energy of 3.29 eV. With increasing shear strain the lamellar structure breaks down and a two-phase fine-grained globular structure develops by recrystallization with a grain size in the order of 2 microns. The weak initial fibre textures at high strains are randomized. The mechanical, microstructural and textural features indicate a transition from dislocation creep to superplastic flow.

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A model of continuous dynamic recrystallization

Cited by 726 publications

References 18 publications

Optimization of Microstructure and Mechanical Properties of Co–Cr–Mo Alloys by High-Pressure Torsion and Subsequent Short Annealing

Optimization of Microstructure and Mechanical Properties of Co–Cr–Mo Alloys by High-Pressure Torsion and Subsequent Short Annealing

Development of Microstructure and Crystallographic Texture in a Double-Sided Friction Stir Welded Microalloyed Steel

High strain torsion of a TiAl-based alloy

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