scholarly journals Effect of the austenitizing temperature on the kinetics of ferritic grain growth under continuous cooling of a Nb microalloyed steel

2004 ◽  
Vol 51 (7) ◽  
pp. 721-725 ◽  
Author(s):  
A.B. Cota ◽  
C.A.M. Lacerda ◽  
F.L.G. Oliveira ◽  
F.A. Machado ◽  
da Silva Araújo
Keyword(s):  
Grain Growth ◽  
Microalloyed Steel ◽  
Austenitizing Temperature ◽  
Continuous Cooling ◽  
Nb Microalloyed Steel ◽  
Kinetics Of

Microstructure Characteristics in Continuous Cooling Transformation of an Nb Microalloyed Steel

2011 ◽  
Vol 228-229 ◽  
pp. 72-76
Author(s):  
J. H. Yang ◽  
Q. Y. Liu
Keyword(s):  
Microalloyed Steel ◽  
Controlled Rolling ◽  
Controlled Cooling ◽  
Cooling Rates ◽  
Continuous Cooling Transformation ◽  
Microstructure Characteristics ◽  
Continuous Cooling ◽  
Nb Content ◽  
Nb Microalloyed Steel ◽  
Two Stages

Deformation dilatometry has been used to simulate controlled hot rolling followed by controlled cooling of a Nb microalloyed pipeline steels, the microstructure and transformation characteristics in the steel and the effect of deformation on transformation are studied. According to the results of both dilatometry measurements and microstructure observations, the continuous cooling transformation curves (CCT) of the tested steels are constructed. The results show that Nb content and deformation enhance the formation of acicular ferrite; the microstructure of the steel range from PF, QF to AF with increasing of cooling rates from 0.5 to 50°C /s in a two stages controlled rolling and the microstructure revolution is sensitive to cooling rates when it is lower than 5°C /s, however, when the cooling rate increasing further, the microstructure didn’t change very much but M/A constituents in matrix is refined and dispersed.

Phase Transformation Law of Nb Microalloyed Steel at Different Cooling Rates

2021 ◽  
Vol 1035 ◽  
pp. 396-403
Author(s):  
Ping Yu ◽  
Ren Bo Song ◽  
Wen Ming Xiong ◽  
Wei Feng Huo ◽  
Chen Wei ◽  
...  
Keyword(s):  
Phase Transition ◽  
Phase Transformation ◽  
Cooling Rate ◽  
Microalloyed Steel ◽  
Transition Diagram ◽  
Diffusion Type ◽  
Continuous Cooling ◽  
Type Phase ◽  
Test Steel ◽  
Nb Microalloyed Steel

Through the Gleeble3500 thermal simulation test machine, the phase transformation law of Nb microalloyed steel was studied and tested. After the compression deformation, it was cooled to room temperature at different speeds. Obtain the dynamic continuous cooling transformation diagram and the scanning structure diagram of the test steel, and then analyze the phase composition under different cooling speeds through JMatPro material performance simulation. The results show that: at a lower cooling speed (0.1°C/s), austenite decomposition is a diffusion-type phase change that takes place in a high-temperature region, and carbon atoms can diffuse sufficiently. At a moderate cooling rate (1°C/s), the bainite phase transition is a semi-diffusion phase transition in which carbon atoms are displaced in a non-cooperative thermally activated transition mode. When the cooling rate is high (15°C/s), the martensitic transformation is a non-diffusion-type transformation carried out in the low temperature region, and the atoms are directly transferred from the austenite lattice to the martensite lattice. With the increase of the cooling rate and the decrease of the transition temperature, from low-speed cooling→medium-speed cooling→high-speed cooling, respectively, the diffusion type phase transition→semi-diffusion type phase transition→the non-diffusion type phase transition. At different cooling rates, the continuous cooling transition diagram simulated by JMatPro is basically the same as the phase transition in the dynamic continuous cooling transition diagram of the test steel, which proves that the simulation prediction of the dynamic continuous cooling transition of the test steel by the JMatPro software has high accuracy and applicability.

Precipitation kinetics of NbC in ferrite of a Nb microalloyed steel

2004 ◽  
Vol 120 ◽  
pp. 563-570
Author(s):  
Y.-H. Choi ◽  
H.-C. Shin ◽  
C.-S. Choi ◽  
Y.-K. Lee
Keyword(s):  
Microalloyed Steel ◽  
Ferrite Matrix ◽  
Nucleation And Growth ◽  
Lever Rule ◽  
Time Diagram ◽  
Precipitation Kinetics ◽  
Good Match ◽  
Nb Microalloyed Steel ◽  
Kinetics Of ◽  
Temperature Time

The precipitation kinetics of NbC in ferrite matrix of a Nb microalloyed steel was investigated experimentally and numerically. The change in electrical resistivity due to NbC precipitation was measured at different constant temperatures as a function of holding time and was converted to the precipitation kinetics of NbC using a lever rule. The precipitation kinetics was compared with a classical nucleation and growth model and with the hardness. There is a good match among the calculated and measured precipitation kinetics of NbC and the hardness. The numerical and experimental results have been used to construct a precipitation-temperature-time diagram of NbC in ferrite matrix of the Nb microalloyed steel.

scholarly journals In situ measurement and modelling of austenite grain growth in a Ti/Nb microalloyed steel

2012 ◽  
Vol 60 (3) ◽  
pp. 1015-1026 ◽  
Author(s):  
M. Maalekian ◽  
R. Radis ◽  
M. Militzer ◽  
A. Moreau ◽  
W.J. Poole
Keyword(s):  
Grain Growth ◽  
Microalloyed Steel ◽  
In Situ Measurement ◽  
Austenite Grain ◽  
Nb Microalloyed Steel ◽  
Austenite Grain Growth

scholarly journals THE IMPACT OF AUSTENITIZATION TEMPERATURE ON A STRUCTURES FORMATION UNDER CONTINUOUS COOLING OF THE CHROMO-MOLYBDENUM STEEL

2017 ◽  
pp. 13-16
Author(s):  
V. A. Lutsenko ◽  
T. N. Golubenko ◽  
O. V. Lutsenko ◽  
N. A. Glazunova
Keyword(s):  
Grain Growth ◽  
Decay Process ◽  
Austenitization Temperature ◽  
Continuous Cooling ◽  
Austenite Grain ◽  
Molybdenum Steel ◽  
The Stability ◽  
The Impact ◽  
Austenite Grain Growth ◽  
Kinetics Of

The impact of the austenite grain growth of chromo-molybdenum steel on the kinetics of structural decomposition under continuous cooling was studied. It is shown that when the grain is enlarged with an increase in the austenitization temperature from 850 till 1050 °C, the stability of the supercooled austenite in the structure of the chromo-molybdenum steel during the decay process by the intermediate and shear mechanism increases, which contributes to a decrease in the critical quenching rate.

Effect of the Strain Reversal on the Microstructure and the Recrystallization Kinetics of the Austenite

2004 ◽  
Vol 467-470 ◽  
pp. 275-280 ◽  
Author(s):  
D. Jorge-Badiola ◽  
Amaia Iza-Mendia ◽  
Isabel Gutiérrez
Keyword(s):  
Stainless Steel ◽  
Austenitic Stainless Steel ◽  
Static Recrystallization ◽  
Microalloyed Steel ◽  
Hot Working ◽  
Recrystallization Kinetics ◽  
Static Softening ◽  
Nb Microalloyed Steel ◽  
Strain Reversal ◽  
Kinetics Of

It has been demonstrated recently that when a reversion of the strain is applied during the hot working of a Nb-microalloyed steel, the subsequent static recrystallization kinetics is significantly affected. However, depending on the magnitude of the reversion, the static softening kinetics can be accelerated or delayed. This relates to the substructure dissolution taking place by the effect of the reversal. In the present work, new microstructural results obtained by EBSD on an austenitic stainless steel hot deformed by torsion is used to explain better the observed effect of the reversion of the strain.

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