Modeling of the Resistance to Hot Deformation and the Effects of Microalloying in High-Al Steels under Industrial Conditions

2005 ◽  
Vol 500-501 ◽  
pp. 195-202 ◽  
Author(s):  
Fulvio Siciliano ◽  
Evgueni I. Poliak
Keyword(s):  
Flow Stress ◽  
Hot Deformation ◽  
High Strength ◽  
Microalloyed Steels ◽  
Hot Strip Mill ◽  
Mean Flow ◽  
Hot Strip Rolling ◽  
Strip Rolling ◽  
Hot Strip ◽  
Mean Flow Stress

The hot strip rolling of advanced microalloyed high strength steels still represents a new task to many mills due to the lack of data on the hot deformation resistance. With the aid of processing data from the Ispat-Inland hot strip mill, the “measured mean flow stresses” are calculated from the mill force using the Sims analysis and taking into account roll flattening, slip ratio and the redundant strain. A modification of the Misaka mean flow stress equation is proposed for C – Mn – Si – Al steels microalloyed with up to 0.02 % Nb. The effects of alloying and microalloying are then estimated. A new fitting parameter shows excellent agreement with the mean flow stress data from industrial processing of advanced high strength microalloyed steels. However, during the second half of the rolling schedule (lower temperature region), indications of austeniteto- ferrite transformation were found.

Application of Deformation to Improve Hot Ductility in the Peritectic Steel

2005 ◽  
Vol 500-501 ◽  
pp. 203-210 ◽  
Author(s):  
Ahmad Rezaeian ◽  
Faramarz Zarandi ◽  
D.Q. Bai ◽  
Steve Yue
Keyword(s):  
Flow Stress ◽  
High Strength ◽  
Microalloyed Steels ◽  
Hot Strip Mill ◽  
Mean Flow ◽  
Hot Strip Rolling ◽  
Strip Rolling ◽  
Slip Ratio ◽  
Hot Strip ◽  
Mean Flow Stress

The hot strip rolling of advanced microalloyed high strength steels still represents a new task to many mills due to the lack of data on the hot deformation resistance. With the aid of processing data from the Ispat-Inland hot strip mill, the “measured mean flow stresses” are calculated from the mill force using the Sims analysis and taking into account roll flattening, slip ratio and the redundant strain. A modification of the Misaka mean flow stress equation is proposed for C – Mn – Si – Al steels microalloyed with up to 0.02 % Nb. The effects of alloying and microalloying are then estimated. A new fitting parameter shows excellent agreement with the mean flow stress data from industrial processing of advanced high strength microalloyed steels. However, during the second half of the rolling schedule (lower temperature region), indications of austeniteto- ferrite transformation were found.

scholarly journals Prediction of Mean Flow Stress during Hot Strip Rolling Using Genetic Algorithms

2014 ◽  
Vol 54 (1) ◽  
pp. 171-178 ◽  
Author(s):  
Antonella Dimatteo ◽  
Marco Vannucci ◽  
Valentina Colla
Keyword(s):  
Genetic Algorithms ◽  
Flow Stress ◽  
Mean Flow ◽  
Hot Strip Rolling ◽  
Strip Rolling ◽  
Hot Strip ◽  
Mean Flow Stress

scholarly journals Mathematical Modeling of Mean Flow Stress during the Hot Strip Rolling of Nb Steels.

1996 ◽  
Vol 36 (12) ◽  
pp. 1507-1515 ◽  
Author(s):  
K. Minami ◽  
F. Siciliano, Jr. ◽  
T. M. Maccagno ◽  
J. J. Jonas
Keyword(s):  
Mathematical Modeling ◽  
Flow Stress ◽  
Mean Flow ◽  
Hot Strip Rolling ◽  
Strip Rolling ◽  
Hot Strip ◽  
Mean Flow Stress

Prediction of the Microstructural Evolution during Hot Strip Rolling of Nb Microalloyed Steels

2007 ◽  
Vol 558-559 ◽  
pp. 1127-1132 ◽  
Author(s):  
Linda Lissel ◽  
Göran Engberg
Keyword(s):  
Flow Stress ◽  
Microstructural Evolution ◽  
Microalloyed Steels ◽  
Hot Strip Mill ◽  
Force Model ◽  
Hot Strip Rolling ◽  
Strip Rolling ◽  
Physical Description ◽  
Hot Strip ◽  
Physically Based

A physically based model is used to describe the microstructural evolution of Nb microalloyed steels during hot rolling. The model is based on a physical description of dislocation density evolution, where the generation and recovery of dislocations determines the flow stress and also the driving force for recrystallization. In the model, abnormally growing subgrains are assumed to be the nuclei of recrystallized grains and recrystallization starts when the subgrains reach a critical size and configuration. The model is used to predict the flow stress during rolling in SSAB Tunnplåt’s hot strip mill. The predicted flow stress in each stand was compared to the stresses calculated by a friction-hill roll-force model. Good fit is obtained between the predicted values by the microstructure model and the measured mill data, with an agreement generally within the interval ±15%.

Modeling of the Microstructural Evolution and Mean Flow Stress during Thin Slab Casting/Direct Rolling of Niobium Microalloyed Steels

2005 ◽  
Vol 500-501 ◽  
pp. 221-228 ◽  
Author(s):  
Fulvio Siciliano ◽  
L.L. Leduc
Keyword(s):  
Flow Stress ◽  
Microalloyed Steels ◽  
Hot Strip Mill ◽  
Thin Slab ◽  
Mean Flow ◽  
Thin Slab Casting ◽  
Slab Casting ◽  
Mean Flow Stress ◽  
Direct Rolling ◽  
The Mean

Mill logs obtained from the Hylsa CSPTM (thin slab casting/direct rolling – TSC/DR) mill were examined so that the mean flow stresses at each pass were calculated using the Sims equation modified to take into account the forward slip ratio, the redundant strain and the work roll flattening. The mean flow stresses were then compared to predicted values obtained from a model. The microstructures during the CSP process were predicted by a mathematical model which was initially derived for conventional slab/roughing mill/hot strip mill (HSM) processing route. The adapted model takes into account the deformation of the as-cast structure in the finishing CSP mill, by using particular microstructural equations to calculate the softening kinetics and grain sizes. The main metallurgical features such as the occurrence of Nb(C,N) precipitation, the softening mechanism which takes place (static or metadynamic recrystallization) as well as the strain accumulation between passes were calculated. The mean-flow-stress results obtained from the calculations are in good agreement with the mill data. The present analysis indicates that it is possible to produce fine-grained microalloyed steels with homogeneous microstructure in thin slab casting/direct rolling processing.

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