The Deformation and Ageing of Mild Steel: II Characteristics of the L ders Deformation

Hall, E. O.

doi:10.1088/0370-1301/64/9/302

Cited by 433 publications

(136 citation statements)

References 3 publications

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“…[32,33] However, a value of m ϭ 1 is generally preferred, because a negative value of 0 is sometimes obtained when the Hall-Petch relationship is employed. Data on the hardness vs the reciprocal of interlamellar spacing for selected steels are shown in Figure 10(b).…”

Section: Si-022v) the Results Of The Trials Are Summarized Inmentioning

confidence: 99%

Optimization of mechanical properties of high-carbon pearlitic steels with Si and V additions

Han

Edmonds

Smith

2001

Metall Mater Trans A

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Systematic research has been undertaken on the effects of single and combined additions of vanadium and silicon on the mechanical properties of pearlitic steels being developed for wire rod production. Mechanical test results demonstrate that the alloy additions are beneficial to the mechanical properties of the steels, especially the tensile strength. Silicon strengthens pearlite mainly by solid-solution strengthening of the ferrite phase. Vanadium increases the strength of pearlite mainly by precipitation strengthening of the pearlitic ferrite. When added separately, these elements produce relatively greater strengthening at higher transformation temperatures. When added in combination the behavior is different, and substantial strength increments are produced at all transformation temperatures studied (550 ЊC to 650 ЊC). The addition of silicon and vanadium to very-high-carbon steels (Ͼ0.8 wt pct C) also suppresses the formation of a network of continuous grain-boundary cementite, so that these hypereutectoid materials have high strength coupled with adequate ductility for cold drawing. A wiredrawing trial showed that total drawing reductions in area of 90 pct could be obtained, leading to final tensile strengths of up to 2540 MPa in 3.3-mm-diameter wires.

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Section: Si-022v) the Results Of The Trials Are Summarized Inmentioning

confidence: 99%

Optimization of mechanical properties of high-carbon pearlitic steels with Si and V additions

Han

Edmonds

Smith

2001

Metall Mater Trans A

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“…While deformation mechanisms that govern the decrease of hardness with increasing d in the larger grain size regime are already reasonably well understood in the context of the Hall-Petch relation [24,25], mechanisms that govern friction and its dependence on d are still unknown. To analyze the latter mechanisms, in Fig.…”

Section: Fig 3 (Color Online) (A) Hardness and (B) Friction Coefficmentioning

confidence: 99%

How grain size controls friction and wear in nanocrystalline metals

Szlufarska

2015

Phys. Rev. B

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Using molecular simulations we investigated the dependence of friction and wear on grain size in nanocrystalline copper. We found that effects of grain size are coupled to the effects of contact size, resulting in a transition from grain-size sensitive regime to grain size-insensitive regime in friction. This transition occurs because for small tips, frictioninduced easy shear planes can be entirely accommodated in a single grain, rendering grain boundaries less relevant to sliding resistance. Trends in friction do not follow trends in hardness, which is sensitive to grain diameter in the entire grain size regime considered in this study. We have also discovered that coupling of the effects of grain diameter and contact size leads to an optimum grain size that minimizes formation of wear chips on the surface. 1. IntroductionGrain refinement to the nanometer regime has been shown to have important nonmonotonic effects on mechanical properties of metals. Specifically, a number of studies reported existence of an optimum grain size that maximizes strength and hardness of metallic systems. [1,2] This maximum strength corresponds to the grain diameter for which mechanisms of deformation transition from being dominated by intragranular dislocation plasticity to grain boundary (GB) sliding. In addition to this intrinsic grain size effect, mechanical properties can depend on the dimensions of the specimen -a socalled extrinsic size effect. For instance, mechanical strength of metallic nanopillars can be significantly lower [3] or higher [4] than the strength of the corresponding bulk samples.Grain refinement has been also shown to be a highly promising path for improving friction and wear resistance of metals. [5,6] However, despite these promising reports, at present the effects of grain size on wear and friction of nc metals are far from understood. For instance, it is unknown whether there is specific grain size that minimizes friction and wear or how the underlying mechanisms depend on the details of the microstructure. Molecular dynamics (MD) simulations have greatly contributed to discoveries of size effects in plasticity and of deformation mechanisms in nc metals during uniform shear, compression and during nanoindentation, [1,2,[7][8][9][10] but MD simulations of wear of nc materials have only been reported in the last few years [11][12][13]. For example, the authors of Ref.[13] performed MD simulations of tip sliding on nc copper and discovered formation of folds in the worn material. This finding was supported by observations from atomic force microscopy (AFM) experiments. However, the grain size effect on friction and wear and on the underlying mechanisms of deformation were not explored in that study.

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“…A common feature of HallPetch measurements 1,2) to study the strengthening of materials due to grain refinement is that they are almost always carried out at room temperature, regardless of the melting point of the material. However, depending on the absolute melting point T m of a material, its homologous temperature T/T m at room temperature may vary considerably ® for example, it is 0.1 for molybdenum and 0.43 for zinc.…”

Section: Introductionmentioning

confidence: 99%

Hall–Petch Breakdown at Elevated Temperatures

Schneibel¹,

Heilmaier

2014

Mater. Trans.

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The HallPetch effect responsible for the strength of fine-grained and ultrafine-grained (UFG) metals is almost exclusively measured at room temperature. One reason for this is that at elevated temperatures grains tend to coarsen, and this negates the strengthening. The grains may, however, be stabilized by small volume fractions of fine dispersoids. These dispersoids cause direct Orowan strengthening and, by stabilizing the so-called Zener grain size, indirect strengthening due to HallPetch. We show that for most metals the critical Zener grain size above which HallPetch strengthening is more important than Orowan strengthening is lower than, and sometimes even considerably lower than 1 µm, i.e., in the range of UFG metals. Breakdown of the HallPetch relationship, which occurs at elevated temperatures once mechanisms weaker than Hall Petch start to control the strength, is best studied for grain sizes well above this critical grain size. The HallPetch breakdown due to either Coble creep or grain size-dependent dislocation creep is modeled. We present model calculations for copper and verify our approach by comparing with experimental results for ferritic steels containing nanoscale dispersions.

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The Deformation and Ageing of Mild Steel: II Characteristics of the L ders Deformation

Cited by 433 publications

References 3 publications

Optimization of mechanical properties of high-carbon pearlitic steels with Si and V additions

Optimization of mechanical properties of high-carbon pearlitic steels with Si and V additions

How grain size controls friction and wear in nanocrystalline metals

Hall–Petch Breakdown at Elevated Temperatures

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The Deformation and Ageing of Mild Steel: II Characteristics of the L ders Deformation

Cited by 433 publications

References 3 publications

Optimization of mechanical properties of high-carbon pearlitic steels with Si and V additions

Optimization of mechanical properties of high-carbon pearlitic steels with Si and V additions

How grain size controls friction and wear in nanocrystalline metals

Hall&ndash;Petch Breakdown at Elevated Temperatures

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Hall–Petch Breakdown at Elevated Temperatures