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.

Effect of Austenite Deformation on Recrystallisation Behaviour in an X-70 Microalloyed Steel

2010 ◽  
Vol 89-91 ◽  
pp. 721-726 ◽  
Author(s):  
Lin Sun ◽  
Bradley P. Wynne ◽  
Eric J. Palmiere
Keyword(s):  
Microalloyed Steel ◽  
Pipeline Steel ◽  
Current Model ◽  
Compression Tests ◽  
Precipitation Kinetics ◽  
Start Time ◽  
Critical Temperatures ◽  
Softening Parameter ◽  
Fractional Softening ◽  
Kinetics Of

In the present study, the effect of austenite deformation on the recrystallisation behaviour in terms of recrystallisation-stop and recrystallisation-limit temperatures (T5% and T95%) of an X70 niobium microalloyed pipeline steel have been investigated by interrupted plane strain compression tests. The extents of recrystallisation are calculated using a modified fractional softening parameter. And the 20% and 60% of fractional softening were correlated to T5% and T95%. Quantitative optical metallography indicates that this method provides for a convenient and reliable experimental measurement of the critical temperatures associated with the recrystallisation of austenite. The recrystallisation kinetics and the precipitation kinetics of Nb(CN) were calculated using two widely applied models. The experimental results from this study suggest that the current model of precipitation kinetics might overestimate the precipitation start time.

Effect of Strain Rate on the Subsequent Softening and Precipitation Kinetics in a Nb-Microalloyed Steel

2005 ◽  
Vol 76 (9) ◽  
pp. 650-655
Author(s):  
Haiwen Luo ◽  
Yueling Qin ◽  
Jilt Sietsma ◽  
Sybrand van der Zwaag
Keyword(s):  
Strain Rate ◽  
Microalloyed Steel ◽  
Precipitation Kinetics ◽  
Nb Microalloyed Steel

Effect of Initial Austenite Microstructure on the Softening – Precipitation Interaction in a Low Nb Microalloyed Steel

2007 ◽  
Vol 550 ◽  
pp. 429-434 ◽  
Author(s):  
C. Iparraguirre ◽  
Ana Isabel Fernández-Calvo ◽  
Beatriz López
Keyword(s):  
Grain Size ◽  
Microalloyed Steel ◽  
Recovery Process ◽  
Precipitation Kinetics ◽  
Austenite Grain Size ◽  
Austenite Grain ◽  
Nb Microalloyed Steel ◽  
Niobium Microalloyed Steel ◽  
Softening Fraction

The influence of initial grain size on the softening-precipitation interaction in a low niobium microalloyed steel has been investigated. The study has revealed that for the largest initial grain size (1000 μm), the recrystallised fraction remains lower than the softening fraction until relatively long times are reached. In contrast, for the smallest initial grain size (166 μm) both magnitudes are similar. As a result, precipitation interacts with recrystallisation in the case of the finest austenite grain size, whereas for the coarsest one, since recrystallisation is significantly retarded, interaction with recovery process is observed. Apparently, the initial austenite grain size does not affect precipitation kinetics.

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