Design of dynamic recrystallisation controlled rolling schedules for seamless tube rolling

Pussegoda, L. N.; Hodgson, Peter; Jonas, J. J.

doi:10.1179/026708392790169821

Cited by 25 publications

(9 citation statements)

References 8 publications

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“…The steady-state stress ss can also be described by relations similar to Eqs. [15] and [16]. [3,5] However, the following question arises from the discussion of the previous paragraph does the dynamically recrystallized grain size have a similar effect on the steady-state stress as the initial grain size has on the peak stress?…”

Section: Rtmentioning

confidence: 99%

Modeling the flow behavior of a medium carbon microalloyed steel under hot working conditions

Cabrera

Omar

Prado

et al. 1997

Metall Mater Trans A

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177

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The constitutive equations for the flow behavior of a commercial 0.34 pct C-1.5 pct Mn-0.7 pct Si-0.083 pct V-0.018 pct Ti microalloyed steel were determined. For this purpose, uniaxial hot compression tests were carried out over a wide range of strain rates (10 Ϫ4 to 10 s Ϫ1 ) and temperatures (1123 to 1423 K). In combination with models developed in the literature, the experimental results permit the flow stress of the present steel to be predicted within ‫5ע‬ pct. It is shown that the classical constitutive equations must be modified to take the grain size into account, particularly when the latter is below 30 m.

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Section: Rtmentioning

confidence: 99%

Modeling the flow behavior of a medium carbon microalloyed steel under hot working conditions

Cabrera

Omar

Prado

et al. 1997

Metall Mater Trans A

Self Cite

177

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“…[20] behavior in the stress-strain curve). Circumstantial evidence for the occurrence of DRX in seamless tube rolling [16,17] and Dynamic Recrystallization-Controlled Rolling. This type of process consists of inducing DRX in one or more passes HSMs [18,19,21,22] can be found in the literature.…”

Section: Introductionmentioning

confidence: 98%

“…The analysis of MFS curves as described previously was first proposed by Boratto et al [1] for determination of the (b) three critical temperatures of steel rolling (Ar3, Ar1, and T nr ). [2,3,4] This technique has also been used to deduce that DRX occurs in seamless tube rolling [16,17] as well as in hot strip mills (HSMs). [18,19] Sarmento and Evans [19] came to similar conclusions in their analysis of industrial data from two HSMs.…”

Section: Introductionmentioning

confidence: 99%

Mathematical modeling of the hot strip rolling of microalloyed Nb, multiply-alloyed Cr-Mo, and plain C-Mn steels

Siciliano

Jonas

2000

Metall Mater Trans A

174

105

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Industrial mill logs from seven different hot strip mills (HSMs) were analyzed in order to calculate the mean flow stresses (MFSs) developed in each stand. The schedules were typical of the processing of microalloyed Nb, multiply-alloyed Cr-Mo, and plain C-Mn steels. The calculations, based on the Sims analysis, take into account work roll flattening, redundant strain, and the forward slip ratio. The measured stresses are then compared to the predictions of a model based on an improved Misaka MFS equation, in which solute effects, strain accumulation, and the kinetics of static recrystallization (SRX) and metadynamic recrystallization (MDRX) are fully accounted for. Good agreement between the measured and predicted MFSs is obtained over the whole range of rolling temperatures. The evolution of grain size and the fractional softening are also predicted by the model during all stages of strip rolling. Special attention was paid to the Nb steels, in which the occurrence of Nb(C, N) precipitation strongly influences the rolling behavior, preventing softening between passes. The present study leads to the conclusion that Mn addition retards the strain-induced precipitation of Nb; by contrast, Si addition has an accelerating effect. The critical strain for the onset of dynamic recrystallization (DRX) in Nb steels is derived, and it is shown that the critical strain/peak strain ratio decreases with increasing Nb content; furthermore, Mn and Si have marginal but opposite effects. It is demonstrated that DRX followed by MDRX occurs under most conditions of hot strip rolling; during the initial passes, it is due to high strains, low strain rates, and high temperatures, and, in the final passes, it is a consequence of strain accumulation.

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“…As a result, the kinetics of Nb(C, N) precipitation may be also modeled by an Avrami type equation 43,44) : ............ (16) where X p is the precipitated fraction for a time t, n p the Avrami exponent for precipitation and t 0.05p represents the start time for strain-induced precipitation given by Eq. (10).…”

Section: Amount Of Nb Precipitatedmentioning

confidence: 99%

Improved Model of Kinetics of Strain Induced Precipitation and Microstructure Evolution of Nb Microalloyed Steels during Multipass Rolling

2008

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One of the main problems of empirical and semi-empirical models that are used to predict austenite microstructure evolution during hot rolling is their limited range of applicability regarding chemical compositions. This paper aims to improve a previous microstructural model paying special attention to the development of a more general equation for the prediction of the onset of strain induced precipitation in Nb microalloyed steels. This has been done with the help of new expressions describing the kinetics of strain induced precipitation as a function of the chemical composition. Moreover, the evolution of strain induced Nb precipitation was also modeled in order to determine the amount of Nb precipitated after each strain pass. The predictions obtained with the new model have been compared to results obtained in multipass laboratory tests using several Nb microalloyed steels. The model allows us to better understand the complex interactions occurring between Nb and microstructural softening depending on composition and process parameters.

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Design of dynamic recrystallisation controlled rolling schedules for seamless tube rolling

Cited by 25 publications

References 8 publications

Modeling the flow behavior of a medium carbon microalloyed steel under hot working conditions

Modeling the flow behavior of a medium carbon microalloyed steel under hot working conditions

Mathematical modeling of the hot strip rolling of microalloyed Nb, multiply-alloyed Cr-Mo, and plain C-Mn steels

Improved Model of Kinetics of Strain Induced Precipitation and Microstructure Evolution of Nb Microalloyed Steels during Multipass Rolling

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