The effect of stress and temperature on the velocity of dislocations in pure iron monocrystals

Turner, A.P.L.; Vreeland, T.

doi:10.1016/0001-6160(70)90113-6

Cited by 88 publications

(38 citation statements)

References 8 publications

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“…5, where dislocations do not cross slip in this model. The velocity of the i th dislocation in iron is described by an Arrhenius type empirical low of the form: 30) …”

Section: Model For Two Dimensional Dislocation Dynamics Simulation Himentioning

confidence: 99%

“…The values of the constant parameters used in Equation (11) are obtained from the result of the direct measurement of dislocation velocity in pure iron at 198 K in Ref. 30). The activation energy for dislocation glide used in this study was obtained by Burnner et al 31) as an activation enthalpy for a double kink nucleation along a screw dislocation in iron.…”

Section: Model For Two Dimensional Dislocation Dynamics Simulation Himentioning

confidence: 99%

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Fracture Toughness Enhanced by Grain Boundary Shielding in Submicron-Grained Low Carbon Steel

2008

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The enhancement of toughness at low temperatures in fine grained low carbon steel was studied, basing on a shielding theory due to dislocations and grain boundaries. Fully annealed low carbon steel was subjected to an accumulative roll bonding (ARB) process for grain refining. The grain size perpendicular to the normal direction was found to be approximately 200 nm after the ARB process. The fracture toughness of low carbon steel ARB applied was measured at 77 K by four-point bending, comparing with the fracture toughness of those without the ARB process. It was found that the value of fracture toughness at 77 K was increased by grain refining due to the ARB, indicating that the ARB process enhances toughness at low temperatures as reported in interstitial free steel and phosphorus doped interstitial free steel. It also deduces that the brittle-ductile transition (BDT) temperature shifted to a lower temperature. The enhancement of toughness and the decrease of the BDT temperature due to grain refining cannot be explained completely by the dislocation pile-up model of dislocations at grain boundaries. Quasi-two-dimensional simulations of dislocation dynamics, taking into account of crack tip shielding due to dislocations, were performed to investigate the effect of a dislocation source spacing along a crack front on the BDT. The simulation indicated that the BDT temperature is decreased by decreasing the dislocation source spacing. In addition to the simulation, the authors suggest a new concept of accommodating stress intensity at the crack tip due to grain boundaries to explain the enhancement of toughness and the decrease of the BDT temperature in fine grained materials.

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“…5, where dislocations do not cross slip in this model. The velocity of the i th dislocation in iron is described by an Arrhenius type empirical low of the form: 30) …”

Section: Model For Two Dimensional Dislocation Dynamics Simulation Himentioning

confidence: 99%

Section: Model For Two Dimensional Dislocation Dynamics Simulation Himentioning

confidence: 99%

Fracture Toughness Enhanced by Grain Boundary Shielding in Submicron-Grained Low Carbon Steel

2008

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“…Howev<•r after a sufficient stress is reached that fresh dislocations are generated their motion 1s little influenced by the carbon atoms. It would therefore appear that the rate limiting process for dislocation motion in both the pure crystals (1) and those used in this study is the same and that it is not hardening by interstitial impurities. …”

Section: Resultsmentioning

confidence: 77%

“…Sample preparation prior to carburization was the same as previously reported (1). The finished specimens were carburized by heating them to 800°C for 16 hr in a sealed quartz capsule containing an atmosphere of hydrogen and acetylene containing c 14 • The carburization process is described more fully by Stein and Low (2).…”

Section: Methodsmentioning

confidence: 99%