Dislocation versus grain boundary strengthening in SPD processed metals: Non-causal relation between grain size and strength of deformed polycrystals

Starink, M.J.

doi:10.1016/j.msea.2017.08.069

Cited by 56 publications

(22 citation statements)

References 28 publications

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“…where α is a numerical factor, G is the shear modulus, b is the Burgers vector, and ρ is the dislocation density. Assuming a linear function between the dislocation and grain size strengthenings [38][39][40] and taking α = 0.7 [41], G = 81,000 MPa, and b =2.6 × 10 −10 m [20], the dislocation density in the present samples after hot compression can be evaluated varying from 3 × 10 13 m −2 to 8 × 10 13 m −2 . Note, these values are close to those measured in an austenitic stainless steel after hot working under similar conditions [42].…”

Section: Strengthening By Drxmentioning

confidence: 99%

Dynamically Recrystallized Microstructures, Textures, and Tensile Properties of a Hot Worked High-Mn Steel

Dolzhenko

Tikhonova

Kaibyshev

et al. 2019

Metals

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The deformation microstructures and mechanical properties were studied in a high-Mn steel subjected to hot compression. The deformation microstructures resulted from the development of dynamic recrystallization (DRX). Two DRX mechanisms, namely discontinuous and continuous, operated during warm-to-hot working. Under the conditions of hot working when the flow stresses were below 100 MPa, a power law function was obtained between the DRX grain size and the true flow stress with a grain size exponent of −0.8 owing to the discontinuous DRX. On the other hand, the gradual change in the operating DRX mechanism from a discontinuous to continuous one upon a transition from hot to warm working, when the true flow stress increases above 100 MPa, resulted in the grain size exponent of about −0.5 in the power law between the flow stress and the DRX grain size. The DRX microstructures developed by warm-to-hot working provide a beneficial combination of mechanical properties including high ultimate tensile strength in the range of 700–900 MPa and sufficient ductility with a uniform elongation well above 50%. The strengthening of the samples with DRX microstructures was attributed to the combined effect of the grain size and dislocation strengthening resulting in a rather high grain boundary strengthening factor of 570 MPa μm0.5 in the Hall-Petch-type relationship.

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Section: Strengthening By Drxmentioning

confidence: 99%

Dynamically Recrystallized Microstructures, Textures, and Tensile Properties of a Hot Worked High-Mn Steel

Dolzhenko

Tikhonova

Kaibyshev

et al. 2019

Metals

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“…The trouble with this approach is that the dislocation density is hard to be measured accurately. Recently, the dislocation density in cold worked metals and alloys has been shown to correlate with the density of grain boundaries, leading to a linear dependence between the dislocation strengthening and the grain size strengthening [59]. Thus, the strengthening by cold working can be evaluated by using either dislocation density or grain size.…”

Section: Deformation Strengtheningmentioning

confidence: 99%

Grain refinement and strengthening of austenitic stainless steels during large strain cold rolling

Odnobokova

Belyakov

Kaibyshev

2018

Philosophical Magazine

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The microstructure/texture evolution and strengthening of 316 L-type and 304 L-type austenitic stainless steels during cold rolling were studied. The cold rolling was accompanied by the deformation twinning and micro-shear banding followed by the strain-induced martensitic transformation, leading to nanocrystalline microstructures consisting of flattened austenite and martensite grains. The fraction of ultrafine grains can be expressed by a modified Johnson-Mehl-Avrami-Kolmogorov equation, while inverse exponential function holds as a first approximation between the mean grain size (austenite or martensite) and the total strain. The deformation austenite was characterised by the texture components of Brass, {011}<211>, Goss, {011}<100>, and S, {123}<634>, whereas the deformation martensite exhibited a strong {223}<110> texture component along with remarkable γ-fibre, <111>∥ND, with a maximum at {111}<211>. The grain refinement during cold rolling led to substantial strengthening, which could be expressed by a summation of the austenite and martensite strengthening contributions.

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“…In other words, the absorbed internal energy of the specimen mainly contributes to the grain deformation (slipping and twining). With the increasing grain number per unit volume, the increasing grain boundary strengthening [26,27] and strong dislocation density [12,28] are obtained to enhance the deformation resistance, and this ultimately leads to an intensified energy consumption. Therefore, there is a certain relationship between E and the grain number per unit volume.…”

Section: Discussionmentioning

confidence: 99%

New Constitutive Model for the Size Effect on Flow Stress Based on the Energy Conservation Law

Wang

Chen

et al. 2020

Materials

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In this study, a new model involving energy is established to characterize the size effect on flow stress. The new model treats the experimental machine and the specimen as an isolated system, and this isolated system satisfies the Energy Conservation Law. The total work performed on the specimen by the experimental machine is nearly equal to the energy consumed by the specimen plastic deformation and the energy consumed by friction (which can be ignored when working without friction). The new model predicts the energy consumption of the specimen deformation by quantifying the total energy input to the specimen by the experimental machine and then obtaining the relevant parameters of the constitutive model. Through uniaxial tensile tests of pure nickel thin sheets with various thickness/average grain sizes (t/d), the new model was used to optimize the parameters of the existing constitutive model that predicts the flow stress of specimens with different t/d. The prediction accuracy of the optimized constitutive model is improved, especially for specimens with a t/d < 1. The new model is established from the perspective of energy input to avoid the analysis of the material deformation mechanism and improve the prediction accuracy.

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Dislocation versus grain boundary strengthening in SPD processed metals: Non-causal relation between grain size and strength of deformed polycrystals

Cited by 56 publications

References 28 publications

Dynamically Recrystallized Microstructures, Textures, and Tensile Properties of a Hot Worked High-Mn Steel

Dynamically Recrystallized Microstructures, Textures, and Tensile Properties of a Hot Worked High-Mn Steel

Grain refinement and strengthening of austenitic stainless steels during large strain cold rolling

New Constitutive Model for the Size Effect on Flow Stress Based on the Energy Conservation Law

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