New Phenomenological Model of Hot Mean Flow Stress

2013 ◽  
Vol 32 (2) ◽  
pp. 133-138
Author(s):  
Ivo Schindler ◽  
Petr Kawulok ◽  
Stanislav Rusz ◽  
Jiří Plura ◽  
Zdeňek Vašek ◽  
...  
Keyword(s):  
Flow Stress ◽  
Hot Rolling ◽  
Effective Strain ◽  
Single Equation ◽  
Mean Flow ◽  
Strain And Strain Rate ◽  
Wide Range ◽  
Mean Flow Stress ◽  
Experimental Values ◽  
Fast Prediction

AbstractBased on the measurement of roll forces during the laboratory hot rolling of flat samples graded in thickness, the new phenomenological type of mean flow stress model was developed and applied on plain-carbon and HSLA steels. The obtained models describe with a very good accuracy the hot deformation resistance characteristics in the temperature range 1123 to 1463 K, large effective strain, and strain rate in the useful range of approximately 10 to 100 s−1. Difficulty in the mathematical description of the influence of temperature on mean flow stress in the wide range of temperature by a single equation was solved by introducing another constant in the temperature member of the conventional model. The newly proposed model solves by phenomenological means a frequent problem of heteroscedasticity of relative deviations between the calculated and experimental values of mean flow stress values depending on temperature. It becomes more reliable from the viewpoint of the operational application, e.g. fast prediction of mean flow stress values and power/force parameters necessary in the steering systems of hot rolling mills.

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 Convective Pattern Deformations under Mean Flow Stress

1987 ◽  
Vol 4 (2) ◽  
pp. 253-253 ◽  
Author(s):  
A Pocheau ◽  
V Croquette ◽  
P. Le Gal ◽  
C Poitou
Keyword(s):  
Flow Stress ◽  
Mean Flow ◽  
Mean Flow Stress ◽  
Convective Pattern

scholarly journals Study of the Microstructure and Strain Induced Precipitation during Thermomechanical Processing of Low Carbon Microalloyed Steels

2012 ◽  
Vol 706-709 ◽  
pp. 2118-2123
Author(s):  
Manuel Gómez ◽  
Pilar Valles ◽  
Sebastián F. Medina
Keyword(s):  
Hot Rolling ◽  
Thermomechanical Processing ◽  
High Strength ◽  
Transformation Products ◽  
Carbon Steels ◽  
Microalloyed Steels ◽  
Low Carbon ◽  
Mean Flow ◽  
Wide Range ◽  
Final Microstructure

A series of anisothermal multipass hot torsion tests were carried out to simulate hot rolling on three high-strength low-carbon steels with different amounts of Mn, Mo, Nb and Ti and designed for pipeline construction. Mean Flow Stress was graphically represented against the inverse of temperature to characterize the evolution of austenite microstructure during rolling. The effect of austenite strengthening obtained at the end of thermomechanical processing on the final microstructure obtained after cooling was studied. Higher levels of austenite strengthening before cooling promote a refinement of final microstructure but can also restrict the fraction of low-temperature transformation products such as acicular ferrite. This combined effect gives rise to a wide range of final microstructures and mechanical properties depending on the composition, processing schedule and cooling rates applied. On the other hand, the precipitation state obtained at diverse temperatures during and at the end of hot rolling schedule was evaluated by means of transmission electron microscopy (TEM) in two microalloyed steels. It was found that two families of precipitates with different morphology, composition and mean size can coexist in microalloyed steels.

Study on Flow Stress Model of a Microalloyed High Strength Steel in CSP Hot Rolling

2008 ◽  
Vol 575-578 ◽  
pp. 267-272
Author(s):  
Guang Xu ◽  
Lun Wan ◽  
Xin Qiang Zhang ◽  
Zheng Liang Xue
Keyword(s):  
Flow Stress ◽  
Hot Rolling ◽  
High Strength Steel ◽  
High Strength ◽  
Prediction Errors ◽  
Stress Model ◽  
Strain And Strain Rate ◽  
Stress Prediction ◽  
Stress Models ◽  
Flow Stress Model

Hot simulation tests at different deformation technology parameters were carried out for a microalloyed high strength steel produced by CSP hot rolling and the stress-strain curves during deformation were measured. Based on the experimental results and the discussions of present flow stress models, a new flow stress model incorporating interactional effect of deformation temperature, strain and strain rate on flow stress was developed in the paper. Excellent agreement between measured and predicted flow stress values is obtained for new flow stress model of a microalloyed high strength steel rolled by CSP. In addition, the comparisons of flow stress prediction errors between several models and one given in the paper reveal that the prediction accuracy of new flow stress model presented in the paper is higher than other models.

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