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

Pereda, Beatriz; Rodríguez-Ibabe, J.M.; López, Beatriz

doi:10.2355/isijinternational.48.1457

Cited by 37 publications

(37 citation statements)

References 43 publications

Supporting

Mentioning

Contrasting

Unclassified

Order By: Relevance

“…The Nb cluster, Nb-C cluster and Nb-rich precipitate number densities increased with a decrease in deformation temperature due to an increase in TMP time (time of cooling from the roughing to the finishing deformation temperature). This corresponds to the theoretically predicted and experimentally observed dependences of Nb precipitation kinetics on temperature [16,17,35,36].…”

Section: Discussionsupporting

confidence: 86%

See 1 more Smart Citation

Effect of deformation temperature on niobium clustering, precipitation and austenite recrystallisation in a Nb–Ti microalloyed steel

Kostryzhev

Shahrani

Zhu

et al. 2013

Materials Science and Engineering: A

View full text Add to dashboard Cite

The effect of deformation temperature on Nb solute clustering, precipitation and the kinetics of austenite recrystallisation were studied in a steel containing 0.081C-0.021Ti-0.064 Nb (wt%). Thermo-mechanical processing was carried out using a Gleeble 3500 simulator. The austenite microstructure was studied using a combination of optical microscopy, transmission electron microscopy, and atom probe microscopy, enabling a careful characterisation of grain size, as well as Nb-rich clustering and precipitation processes. A correlation between the austenite recrystallisation kinetics and the chemistry, size and number density of Nb-rich solute atom clusters, and NbTi(C,N) precipitates was established via the austenite deformation temperature. Specifically, we have determined thresholds for the onset of recrystallisation: for deformation levels above 75% and temperatures above 825 °C, Nb atom clusters recrystallisation AbstractThe effect of deformation temperature on Nb solute clustering, precipitation and the kinetics of austenite recrystallisation were studied in a steel containing 0.081C-0.021Ti-0.064Nb (wt. %). Thermo-mechanical processing was carried out using a Gleeble 3500 simulator. The austenite microstructure was studied using a combination of optical microscopy, transmission electron microscopy, and atom probe microscopy, enabling a careful characterisation of grain size, as well as Nb-rich clustering and precipitation processes. A correlation between the austenite recrystallisation kinetics and the chemistry, size and number density of Nb-rich solute atom clusters, and NbTi(C,N) precipitates was established via the austenite deformation temperature. Specifically, we have determined thresholds for the onset of recrystallisation: for deformation levels above 75 % and temperatures above 825 °C, Nb atom clusters < 8 nm effectively suppressed austenite recrystallisation.

show abstract

Section: Discussionsupporting

confidence: 86%

“…In the deformed samples the Nb-C clustering / precipitation took place within 1-2 s during/after the deformation (time before water quench to room temperature), which is slightly quicker than might be expected from the literature data for similar steel chemistries [2,12,13,[15][16][17][18]35]. This can be explained by the following.…”

Section: Discussionmentioning

confidence: 86%

Effect of deformation temperature on niobium clustering, precipitation and austenite recrystallisation in a Nb–Ti microalloyed steel

Kostryzhev

Shahrani

Zhu

et al. 2013

Materials Science and Engineering: A

View full text Add to dashboard Cite

show abstract

“…However, to use the models, it is necessary to have experimental data and develop equations that consider the effect that Ti and Nb have on the austenite microstructure evolution. Many works have studied the effect of these elements on the austenite recrystallization, grain growth or strain-induced precipitation kinetics [1][2][3]22,23]. However, most of them have focused on conventional Ti additions, while the data on high Ti steels is very scarce and mostly concentrated on the study of TiC precipitation during hot deformation.…”

Section: Introductionmentioning

confidence: 99%

Effect of High Ti Contents on Austenite Microstructural Evolution During Hot Deformation in Low Carbon Nb Microalloyed Steels

García-Sesma

López

Pereda

2020

Metals

View full text Add to dashboard Cite

This work has focused on the study of hot working behavior of Ti-Nb microalloyed steels with high Ti contents (> 0.05%). The role of Nb during the hot deformation of low carbon steels is well known: it mainly retards austenite recrystallization, leading to pancaked austenite microstructures before phase transformation and to refined room temperature microstructures. However, to design rolling schedules that result in properly conditioned austenite microstructures, it is necessary to develop models that take into account the effect of high Ti concentrations on the microstructural evolution of austenite. To that end, in this work torsion tests were performed to investigate the microstructural evolution during hot deformation of steels microalloyed with 0.03% Nb and different high Ti concentrations (0.05%, 0.1%, 0.15%). It was observed that the 0.1% and 0.15% Ti additions resulted in retarded softening kinetics at all the temperatures. This retardation can be mainly attributed to the solute drag effect exerted by Ti in solid solution. The precipitation state of the steels after reheating and after deformation was characterized and the applicability of existing microstructural evolution models was also evaluated. Determined recrystallization kinetics and recrystallized grain sizes reasonably agree with those predicted by equations previously developed for Nb-Ti microalloyed steels with lower Ti concentrations (<0.05%).

show abstract

“…This notably increases activation energy and thereby remarkably retards static recrystallisation. [11][12][13][14] This work shows that the fast kinetics of austenite static recrystallisation in Ti-microalloyed steels (due to the fine size of starting austenite grain at reheating temperatures and in some case also to coarse size of TiN particles) makes it difficult to obtain a severe refinement of ferrite grains by means solely of thermomechanical processing. As a result, unlike other microalloyed steels, conventional controlled rolling of Ti-microalloyed steels can be simplified by significantly reducing the number of rolling passes at high temperatures.…”

Section: Introductionmentioning

confidence: 99%

Simplification of Hot Rolling Schedule in Ti-Microalloyed Steels with Optimised Ti/N Ratio

Gómez¹,

Rancel²,

Gómez³

et al. 2010

ISIJ Int.

View full text Add to dashboard Cite

Thermomechanical simulations have been carried out on two Ti-microalloyed steels and one reference steel without Ti. The pinning forces exerted by TiN particles in the Ti-steels have been determined and compared with the driving forces for austenite grain growth and static recrystallisation between hot rolling passes. The driving forces for recrystallisation were found to be approximately two orders of magnitude higher than the pinning forces, which explains why the austenite in these steels barely experiences hardening during rolling and why the accumulated stress prior to the austenite→ferrite transformation is insufficient to refine the ferritic grain. On the other hand, austenite grain size hardly varies during hot rolling, as the TiN precipitates exert a strong control from the reheating temperature to the last pass. A Ti/N ratio close to 2 is able to control austenite grain growth at high austenitisation temperatures. So, both aspects-high driving forces for static recrystallisation and control on austenite grain size-allow reducing the number of passes applied. In this case, ferrite grain refinement should be reached by austenite strengthening and accelerated cooling during the transformation to ferrite.

show abstract

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

Cited by 37 publications

References 43 publications

Effect of deformation temperature on niobium clustering, precipitation and austenite recrystallisation in a Nb–Ti microalloyed steel

Effect of deformation temperature on niobium clustering, precipitation and austenite recrystallisation in a Nb–Ti microalloyed steel

Effect of High Ti Contents on Austenite Microstructural Evolution During Hot Deformation in Low Carbon Nb Microalloyed Steels

Simplification of Hot Rolling Schedule in Ti-Microalloyed Steels with Optimised Ti/N Ratio

Contact Info

Product

Resources

About