Journal ArticleDOI
Effect of prestrain and deformation temperature on the recrystallization behavior of steels microalloyed with niobium
B. Dutta,Eric J. Palmiere +1 more
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In this article, the authors focused on the effects of prestrain and deformation temperature on the rectrystallization behavior in these steels and proposed a criterion to predict the onset of recrystallisation.Abstract:
The evolution of microstructure during the hot working of steels microalloyed with Nb is governed by the recrystallization kinetics of austenite and the recrystallization-precipitation interaction. The present study focuses on the effects of prestrain and deformation temperature on the rectrystallization behavior in these steels. The extent of recrystallization is characterized by a softening parameter calculated from a series of interrupted plane strain compression tests carried out at different deformation temperatures and strain levels. The results indicate that at low temperatures, softening is caused by static recovery, while at higher temperatures, static recrystallization is the predominant mechanism. The recrystallization-stop temperature (T 5pct) and the recrystallization-limit temperature (T 95pct), marking the beginning and end of recrystallization, respectively, are determined as a function of strain. In order to achieve a homogeneous microstructure, finish rolling should be carried out outside the window of partial recrystallization (T 5pct<T<T 95pct), as determined in this study. The Nb(CN) precipitation kinetics have been calculated using a model proposed in an earlier work, and these results are used to estimate the precipitate pinning force under the given processing conditions. Based on these estimations, a criterion has been proposed to predict the onset of recrystallization. The predicted results are found to be in reasonably good agreement with the experimental measurements.read more
Citations
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Journal ArticleDOI
Grain growth behavior of coarse-grained austenite in a Nb-V-Ti microalloyed steel
Qingyun Sha,Zuqing Sun +1 more
TL;DR: In this paper, the grain growth of coarse-grained austenite during equalization in a simulated thin slab casting and direct rolling process (TSDR) has been studied on a Nb-V-Ti microalloyed steel.
Journal ArticleDOI
Evolution of Austenite Recrystallization and Grain Growth Using Laser Ultrasonics
TL;DR: In this paper, a laser-ultrasonic grain-size measurement technique was extended to examine austenite recrystallization and subsequent grain growth following hot deformation, which was conducted on a low carbon (0.05 wt pct) steel that contains Mn, Mo, and Nb as the three main alloying/microalloying elements.
Journal ArticleDOI
Effect of composition and thermo-mechanical processing schedule on the microstructure, precipitation and strengthening of Nb-microalloyed steel
TL;DR: In this article, the influence of composition and thermo-mechanical processing schedule on the kinetics of austenite recrystallization, strain induced precipitation and final microstructural evolution in Nb-microalloyed steels was studied.
Journal ArticleDOI
Recent Trends in Producing Ultrafine Grained Steels
TL;DR: In this article, an overview of various techniques to fabricate ultra-fine grained steels with different structures is presented, which generally rely on: i) carbon levels, ii) sufficient alloying to obtain the desired transformation temperature and iii) micro-alloying technology in conjunction with Thermo Mechanical Controlled Processes (TMCP) Also, both advanced thermo-mechanical processes and severe plastic deformation strategies are used to produce submicron grain structures with attractive mechanical properties.
Journal ArticleDOI
Static Recrystallization and Precipitation Behavior of a Weathering Steel Microalloyed with Vanadium
TL;DR: In this article, the static recrystallization and precipitation behavior of a weathering steel microalloyed with vanadium were investigated through double-pass compression tests under controlled conditions using the MMS-300 thermal-mechanical simulator.
References
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Stability of microstructure in metallic systems
TL;DR: In this paper, the general problem of the stability of microstructure was discussed. But the authors focused on the structural instability of alloys and did not consider the other causes of microstructural instability.
Journal ArticleDOI
Modelling microstructural development during hot rolling
TL;DR: In this paper, the reasons for computer modelling the pass-by-pass development of microstructure during industrial hot rolling operations are briefly considered, and the principles of modelling are outlined.
Journal ArticleDOI
The Recrystallization Process in Some Polycrystalline Metals
TL;DR: In this paper, a theory based on the known form of the recrystallization kinetics without necessarily introducing any anisotropy of grain boundary mobility is proposed, which is identical to the activation energy for grain boundary migration.
Journal ArticleDOI
A nucleation criterion for dynamic recrystallization during hot working
W Roberts,B Ahlblom +1 more
TL;DR: In this paper, a criterion for the initiation of dynamic recrystallization during hot working is proposed based on the contention that the reduced driving force due to concurrent deformation modifies the normal energy balance which defines the conditions for nucleation of new grains.
Journal ArticleDOI
Effect of composition and process variables on Nb(C, N) precipitation in niobium microalloyed austenite
B. Dutta,C. M. Sellars +1 more
TL;DR: In this article, the authors used nucleation theory and the solubility product of niobium, carbon, and nitrogen in austenite to derive equations for the start of Nb (C, N) precipitation as a function of temperature and composition.
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Effect of composition and process variables on Nb(C, N) precipitation in niobium microalloyed austenite
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