<i>Grain Boundaries in Metals</i>

McLean, David; Maradudin, A. A.

doi:10.1063/1.3062658

Cited by 761 publications

(514 citation statements)

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“…3) The segregation of impurity atoms to microstructural interfaces can have profound effects on the mechanical properties. Theoretical studies by McLean 4) have established a predictive mechanical explanation for the observed segregation behaviour; he proposed that the primary influence on segregation is the lattice distortion energy. Assuming that, at an interface, this energy is small compared to the corresponding energy of a solute atom within the grain interior, the intragranular distortion energy can be taken to be the whole driving force for segregation.…”

Section: Introductionmentioning

confidence: 99%

Static and Dynamic Strain Aging at High Temperatures in 304 Stainless Steel

Stewart

Jonas

2004

ISIJ International

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Commercial 304 austenitic stainless steel was deformed at high temperatures. The experiments involved 2-hit hot compression and multi-pass hot torsion testing; the experimental variables included strain rate, temperature and interpass time. The relationship between these variables and the degree of interpass softening produced unexpected results. Specifically, the normal effect of temperature on the static softening kinetics was reversed at intermediate interpass times: the fractional softening decreased with increasing temperature for these times. The diffusion kinetics and segregation mechanics of the substitutional impurities in the material, combined with the experimental results, suggest that the temporary non-equilibrium segregation of phosphorus (and/or sulphur) to dislocations is responsible for the observed behaviour. Additionally, the observed trend in strain rate sensitivity with increasing deformation temperature indicates that dynamic strain aging was taking place.KEY WORDS: recrystallization; non-equilibrium segregation; stainless steel; static strain aging; dynamic strain aging.rate to vacancy concentration. It has been observed that, under specific thermal and straining conditions, the nonequilibrium segregation of substitutional solutes will occur in steel. 7) This involves the segregation of solute atoms to features such as grain boundaries in concentrations well in excess of equilibrium values. The non-equilibrium segregation is temporary; back diffusion from areas of excess concentration to adjacent regions of solute depletion will return the solute distribution to its equilibrium state given sufficient time. 8) Materials and MethodsThe material used for virtually all the experiments in this work was a 304 austenitic stainless steel obtained from a single billet produced by Atlas Stainless Steel in Tracy, Quebec. In addition, a small amount of ultra-high purity 18Cr-12Ni-Fe 9,10) alloy was obtained and tested. The compositions of these steels are given in Table 1, along with the 304 specifications. Austenitic stainless steel has a low stacking fault energy, 11) in the range 21 mJ m Ϫ2 . Numerous studies of the recrystallization behaviour of such materials have been conducted over the past thirty years (especially involving torsion testing). [12][13][14] The stainless steel tested was obtained in the form of a billet 30-cmϫ15-cmϫ15-cm. The billets were sectioned parallel to the transverse direction and the sections sliced along the normal direction. After machining, the resulting cylindrical samples had their longitudinal axes parallel to the normal direction of the billet. The initial grain size was not a variable of interest in this work, but was essentially constant and in the range 80-100 mm. Torsion samples (Dϭ6.3 mm, Lϭ22 mm) were also machined from the same billet. These were machined such that the longitudinal axis of the samples were aligned along the rolling direction of the billet.Two-hit compression tests were performed primarily for the study of static softening. The tests were co...

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Section: Introductionmentioning

confidence: 99%

Static and Dynamic Strain Aging at High Temperatures in 304 Stainless Steel

Stewart

Jonas

2004

ISIJ International

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“…This is because the area of grain boundary per unit volume, 2/D g , 22) increases with the decrease of the grain diameter. Calculations also show that in the temperature range related to the bake hardening process, 50°C to 200°C, the aging temperature does not really intensify or weaken the effect of this segregation on the formation of the Cottrell atmosphere, see Fig.…”

Section: Figmentioning

confidence: 95%

“…Here the distorted positions in grain boundaries are those which are compressed and, therefore, to which carbon atoms tend to segregate. Taking grain boundaries as 3 atoms thick, 22) one-third of the sites in grain boundaries are compressed. C b (t) can be determined by the following carbon atom balance:…”

Section: Development Of the Theorymentioning

confidence: 99%

“…(8a) Carbon atoms also tend to segregate to grain boundaries to minimize the free energy of the system during aging. 22,23) The dislocations are assumed to distribute homogeneously in the steel. This assumption is reasonable when the prestrain is smaller than 5% and, therefore, no cell formation has yet occurred in the grain.…”

Section: Development Of the Theorymentioning

confidence: 99%

“…Where r is the position measured from the center of a spherical grain, C(t, D g /2) is the atomic fraction of carbon in solution in the grain at the grain boundary with being D g the diameter of the grain, Qϭ62 700 J/mol is the driving force for carbon atoms to segregate to grain boundaries, 22) C b0 and C b (t) are the fraction of the distorted positions in grain boundaries occupied by carbon atoms initially and at time t, respectively. Here the distorted positions in grain boundaries are those which are compressed and, therefore, to which carbon atoms tend to segregate.…”

Section: Development Of the Theorymentioning

confidence: 99%

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A Model for the Cottrell Atmosphere Formation During Aging of Ultra Low Carbon Bake Hardening Steels.

Zhao

Cooman

2000

ISIJ International

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A model describing the formation of the carbon atmosphere around a dislocation during aging of vacuum degassed ultra low carbon bake hardening steels has been developed by extending the original Cottrell theory taking into account the effects of the variation of the free carbon concentration, the saturation of dislocations and the segregation of carbon atoms to grain boundaries. Strain aging experiments have been carried out with an ultra low carbon steel and the experimental results been compared with the theoretical predictions. It is demonstrated that the model developed can describe the formation of Cottrell atmosphere in ultra low carbon bake hardening steels in industrial circumstances.

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Metallurgy of Ultra-Low-C Interstitial-Free Sheet Steel for Automobile Applications

Tsunoyama

1998

phys. stat. sol. (a)

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A review is made on the metallurgy of ultra‐low‐carbon interstitial‐free sheet steel for automotive applications. Basic principles in the development of (111) texture are summarized and differences in Ti and Nb additions are discussed. Development of sheet steel with the r‐value of 2.9 is reported as an application of the present understanding of metallurgy, by employing the currently developed technique of ferrite rolling with lubricant.

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Grain Boundaries in Metals

Cited by 761 publications

References 0 publications

Static and Dynamic Strain Aging at High Temperatures in 304 Stainless Steel

Static and Dynamic Strain Aging at High Temperatures in 304 Stainless Steel

A Model for the Cottrell Atmosphere Formation During Aging of Ultra Low Carbon Bake Hardening Steels.

Metallurgy of Ultra-Low-C Interstitial-Free Sheet Steel for Automobile Applications

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