scholarly journals Physical Simulation Based on Dynamic Transformation Under Hot Plate Rolling of a Nb-Microalloyed Steel

2021 ◽  
Vol 8 ◽  
Author(s):  
João Carlos Ferreira ◽  
Francisco Romario de Sousa Machado ◽  
Clodualdo Aranas ◽  
Fulvio Siciliano ◽  
Jubert Pasco ◽  
...  
Keyword(s):  
Hot Rolling ◽  
Physical Simulation ◽  
Accelerated Cooling ◽  
Mean Flow ◽  
Dynamic Transformation ◽  
Plate Rolling ◽  
Ferrite Fraction ◽  
Mean Flow Stress ◽  
Nb Microalloyed Steel ◽  
Rolling Load

In this work, the presence of dynamically formed ferrite above the Ae3 temperature during the physical simulation of hot rolling was presented. This unusual metallurgical process is known as dynamic transformation (DT). The metastable ferrite phase undergoes a reverse transformation when the temperature is held above the Ae3 by means of a diffusion process. These phenomena affect the rolling load during high-temperature plate rolling. Therefore, a linepipe X70 steel was studied under plate rolling with two-pass roughing and seven-pass finishing strains of 0.4 and 0.2, respectively, applied at strain rate of 1 s−1 and interpasses of 10, 20, and 30 s. The samples were cooling down during deformation, which mimics the actual industrial hot rolling. It was observed that the alloy softens as the hot rolling progresses, as depicted by flow curves and mean flow stress plots, which are linked to the combined effects of dynamic transformation and recrystallization. The former initially occurs at lower strains, followed by the latter at higher strains. The critical strain to DT was affected by the number of passes and temperature of deformation. Shorter interpass time allows higher amounts of ferrite to form due to higher retained work hardening. Similarly, the closer the deformation temperature to the Ae3 permits a higher DT ferrite fraction. The information from this work can be used to predict the formation of phases immediately after hot rolling and optimize models applied to the accelerated cooling.

Physical Simulation Methods Applied to Hot Rolling of Linepipe Steels

2018 ◽  
Vol 941 ◽  
pp. 438-442
Author(s):  
Fulvio Siciliano ◽  
Brian J. Allen ◽  
Samuel F. Rodrigues ◽  
John Joseph Jonas
Keyword(s):  
Hot Rolling ◽  
Physical Simulation ◽  
Simulation Analysis ◽  
Production Costs ◽  
Accelerated Cooling ◽  
Mean Flow ◽  
Mean Flow Stress ◽  
Steel Grades ◽  
Plant Equipment ◽  
Hot Torsion

The simulation of industrial rolling processes has been shown to be an important method to optimize rolling parameters, reduce production costs and improve product quality. Previous works have shown the value of hot rolling simulation by means of torsion tests where the mean-flow-stress (MFS) can be successfully predicted. In the present work, three rolling schedules are simulated by hot torsion tests and compared. It is important to note this methodology provides the flexibility to test different ideas without the risk of downtime or damage to plant equipment that could result from an unsuccessful industrial trial. The simulation analysis considered the production steps from reheating through the final accelerated cooling as well as the final product microstructures. The study provides important information to the production of various steel grades such as pipeline, shipbuilding, structural and other high-end products.

scholarly journals Strain-Induced Ferrite Formation During Steckel Mill Simulations with Varying Roughing Pass Schedules

Metals ◽  
2019 ◽  
Vol 9 (8) ◽  
pp. 814 ◽  
Author(s):  
Henry B. Palhano ◽  
Clodualdo Aranas ◽  
Samuel F. Rodrigues ◽  
Eden S. Silva ◽  
Gedeon S. Reis ◽  
...  
Keyword(s):  
Volume Fraction ◽  
Rolling Process ◽  
Mean Flow ◽  
Dynamic Transformation ◽  
Plate Rolling ◽  
Mean Flow Stress ◽  
The Mean ◽  
Critical Strains ◽  
Microstructure Of The Material ◽  
Very High

It has been previously demonstrated that austenite may undergo partial dynamic transformation (DT) during the plate rolling process. Austenite dynamically transforms into unstable ferrite during hot deformation even at very high temperatures. In this work, the plate rolling simulations, with emphasis on Steckel mill operations, through torsion testing under isothermal conditions were performed on an X70 steel. Four different roughing schedules were tested followed by five finishing passes with pass strains of 0.3 applied at 900 °C. The roughing schedules had zero, one, two and three roughing passes at a temperature of 1100 °C, strain of 0.4 and strain rate of 1 s−1. The stress–strain curves as well as the mean flow stress (MFS) behaviors indicated that both dynamic transformation (DT) and dynamic recrystallization (DRX) occurred during straining. The critical strains for the onset of DT and DRX were determined by means of the double differentiation method and the critical strain values decreased with the number of roughing and finishing strains from the first going to the last pass. It was observed that the volume fraction of the dynamically formed ferrite increased sharply during the finishing stage as the number of previous roughing passes increased, which can be attributed to higher strain accumulation. The results presented here indicate that improved models are needed to control the microstructure of the material during subsequent cooling.

Induced ferrite formation above the Ae3 during plate rolling simulation of a X70 steel

MRS Advances ◽  
2019 ◽  
Vol 4 (57-58) ◽  
pp. 3077-3085
Author(s):  
Samuel F. Rodrigues ◽  
Thiago B. Carneiro ◽  
Clodualdo Aranas ◽  
Eden S. Silva ◽  
Fulvio Siciliano ◽  
...  
Keyword(s):  
Volume Fraction ◽  
Accelerated Cooling ◽  
Strain Accumulation ◽  
Mean Flow ◽  
Ferrite Formation ◽  
Dynamic Transformation ◽  
Cooling Conditions ◽  
Plate Rolling ◽  
Stable Austenite ◽  
The Mean

ABSTRACTPartial amount of austenite can be dynamically transformed into ferrite above the Ae3 temperature when it is being deformed. This happens by a displacive mechanism. On removal of the load, it retransforms back into the stable austenite by diffusional processes. Plate rolling simulation under continuous cooling conditions was carried out on a high Nb X70 steel. Pass strains of 0.2 together with interpass times of 10, 20 and 30 s were employed. The initial and final temperatures for the finishing simulation were 920 and 830 °C, respectively. The mean flow stresses (MFS`s) behaviour indicates that dynamic transformation (DT) and recrystallization (DRX) were taking place during straining. It is shown that ferrite is formed during the roughing passes and increases its volume fraction throughout the finishing rolling steps. The ferrite formation is favoured by strain accumulation, shorter time between passes and also when the temperature reaches the Ae3 line. The results obtained here can be used to design improved models for transformation on accelerated cooling.

Dynamic Transformation during Plate and Strip Rolling

2016 ◽  
Vol 879 ◽  
pp. 29-35 ◽  
Author(s):  
John J. Jonas ◽  
Clodualdo Aranas Jr. ◽  
Samuel F. Rodrigues ◽  
In Ho Jung
Keyword(s):  
Alpha Phase ◽  
Austenite Phase ◽  
Mean Flow ◽  
Volume Percent ◽  
Strip Rolling ◽  
Dynamic Transformation ◽  
Cooling Conditions ◽  
Mean Flow Stress ◽  
Austenite Grains ◽  
Rolling Load

Torsion simulations were carried out of both plate (long interpass times) and strip (short interpass times) rolling. Both isothermal and continuous cooling conditions were employed. The dynamic transformation of austenite to ferrite was observed under all conditions and at all temperatures within the austenite phase field. About 8 to 10 volume percent ferrite was formed in a given pass, leading to about 50 - 70 % ferrite at the end of selected simulations. During the interpass intervals, some retransformation to austenite took place, the amount of which increased with holding time and temperature and decreased with the addition of alloying elements. It is shown that the driving force for the transformation is the softening associated with the replacement of work-hardened austenite grains by the softer alpha phase. The implications with respect to rolling load (i.e. mean flow stress) are also discussed.

Dynamic Transformation of Austenite at Temperatures above the Ae3

2018 ◽  
Vol 941 ◽  
pp. 633-638
Author(s):  
John Joseph Jonas ◽  
Clodualdo Aranas Jr. ◽  
Samuel F. Rodrigues
Keyword(s):  
Electron Microscopy ◽  
Driving Force ◽  
Energy Difference ◽  
Accelerated Cooling ◽  
Free Energy Difference ◽  
Dynamic Transformation ◽  
Plate Rolling ◽  
Temperature Transformation ◽  
Mn Steel ◽  
Kinetics Of

Under loading above the Ae3 temperature, austenite transforms displacively into Widmanstätten ferrite. Here the driving force for transformation is the net softening during the phase change while the obstacle consists of the free energy difference between austenite and ferrite as well as the work of shear accommodation and dilatation during the transformation. Once the driving force is higher than the obstacle, phase transformation occurs. This phenomenon was explored here by means of the optical and electron microscopy of a C-Mn steel deformed above their transformation temperatures. Strain-temperature-transformation (STT) curves are presented that accurately quantify the amount of dynamically formed ferrite; the kinetics of retransformation are also specified in the form of appropriate TTRT diagrams. This technique can be used to improve the models for transformation on accelerated cooling in strip and plate rolling.

Effect of Number of Roughing Passes on the Dynamic Transformation of Austenite during Simulated Plate Rolling

2018 ◽  
Vol 941 ◽  
pp. 717-722
Author(s):  
Samuel F. Rodrigues ◽  
Fulvio Siciliano ◽  
Clodualdo Aranas Jr. ◽  
Gedeon S. Reis ◽  
Brian J. Allen ◽  
...  
Keyword(s):  
Grain Size ◽  
Volume Fraction ◽  
Austenite Phase ◽  
Mean Flow ◽  
Grain Sizes ◽  
Dynamic Transformation ◽  
Plate Rolling ◽  
Forward Transformation ◽  
The Mean ◽  
Rough Rolling

When austenite is deformed within the austenite phase field, it partially transforms dynamically into ferrite. Here, plate rolling simulations were carried out on an X70 steel using rough rolling passes of 0.4 strain each. The influence of the number of roughing passes on the grain size and volume fraction of induced ferrite was determined. Up to three roughing passes applied at 1100 °C followed by 5 finishing passes at 900 °C were employed. The sample microstructures were analysed by means of metallographic techniques. Both the critical strain to the onset of dynamic transformation as well as the grain size decreased with pass number during the roughing simulations. For the finishing passes, the mean flow stresses (MFS`s) applicable to each schedule decreased when a higher number of roughing passes was applied. The volume fraction of dynamically formed ferrite retained after simulated rolling increased with the roughing pass number. This is ascribed to the increased amount of ferrite retransformed into austenite and the finer grain sizes produced during roughing. The forward transformation is considered to occur displacively while the retransformation into austenite during holding takes place by a diffusional mechanism. This indicates that both dynamic transformation (DT) and dynamic recrystallization were taking place during straining.

Physical Simulation of Hot Rolling Steel Plate and Coil Production for Pipeline Applications

2013 ◽  
Vol 762 ◽  
pp. 70-75 ◽  
Author(s):  
Victor Carretero Olalla ◽  
N. Sanchez Mouriño ◽  
Philippe Thibaux ◽  
Leo Kestens ◽  
Roumen H. Petrov
Keyword(s):  
Mechanical Properties ◽  
Hot Rolling ◽  
Physical Simulation ◽  
Thermomechanical Processing ◽  
Charpy Impact ◽  
Processing Parameters ◽  
Accelerated Cooling ◽  
Air Cooling ◽  
Strong Impact ◽  
Structural Characterisation

Within the techniques and equipments used to simulate industrial thermomechanical processing of High Strength Low Alloy (HSLA) pipeline steels, hot rolling laboratory mill equipped with cooling bed and coiling simulation furnace allows, not only accurate control of strains, temperatures, inter-pass times, and cooling rates but also enough amount of processed material for micro-structural characterisation and mechanical testing. Despite some differences with the industrial rolling, laboratory rolling offers a better simulation of the industrial rolling conditions than other thermo-mechanical simulators in terms of deformation mechanisms and processing constrains. This paper presents the results of simulation of different rolling schedules applied on pipeline grades in order to better understand the influence of the finishing rolling parameters namely: finish rolling temperature (FRT) and cooling routes on the microstructure and mechanical properties. It was observed that FRT and cooling rate have a strong impact on both grain refinement and precipitation behaviour, which leads to significant differences in strength and toughness. Furthermore variations of the above mentioned rolling parameters produce distinct fractions and distributions of austenite transformation products, variations in the final crystallographic texture and trigger diverse strengthening mechanisms (i.e. dislocation hardening). It was found that the accelerated cooling in a combination with a coiling simulation results in formation of microstructures with well developed low angle grain boundaries in comparison to the simulation made with air cooling. As a consequence the strength of the plates after accelerated cooling increases without changes in the Charpy impact toughness. It has been shown that the understanding of the effect of processing parameters on the microstructure of these steels is a key aspect for the optimization of their mechanical properties.

scholarly journals Forecasting the mean flow stress of carbon and low-alloy steels in hot rolling on a strip mill

2018 ◽  
Vol 461 ◽  
pp. 012051 ◽  
Author(s):  
Valeriy V Shkatov ◽  
Igor P Mazur ◽  
Victor V Shkatov
Keyword(s):  
Flow Stress ◽  
Hot Rolling ◽  
Low Alloy Steels ◽  
Mean Flow ◽  
Mean Flow Stress ◽  
Alloy Steels ◽  
The Mean

Improving the estimation of mean flow stress within hot rolling of steel by means of different artificial intelligence techniques

2013 ◽  
Vol 46 (9) ◽  
pp. 945-950 ◽  
Author(s):  
Marco Vannucci ◽  
Valentina Colla ◽  
Antonella Dimatteo
Keyword(s):  
Artificial Intelligence ◽  
Flow Stress ◽  
Hot Rolling ◽  
Mean Flow ◽  
Artificial Intelligence Techniques ◽  
Mean Flow Stress

Study on Recrystallization Behaviour of Hot Medium Plate Rolling

2012 ◽  
Vol 482-484 ◽  
pp. 2028-2032
Author(s):  
Ya Qiang Tian ◽  
Fei Tian ◽  
Ying Li Wei ◽  
Jin Ying Song ◽  
Lian Sheng Chen
Keyword(s):  
Hot Rolling ◽  
Static Recrystallization ◽  
Theory Analysis ◽  
Rolling Pressure ◽  
Model Based ◽  
Plate Rolling ◽  
Measurement Results ◽  
Complete Recrystallization ◽  
Rolling Load

The effect regulation of recrystallization softening on rolling load of 16MnR plate hot rolling was studied by means of researching theory analysis and experiment model based on the simulation of the austenitic recrystallization of 16MnR plate hot rolling. The results show that it is static recrystallization totally and almost partial static recrystallization in pass of 16MnR plate hot rolling, the measurement results are in accordance with the prediction value of consideration the effect of recrystallization softening on rolling load of 16MnR plate hot rolling, the Sims equation is suitable for calculating the rolling pressure of the pass after complete recrystallization softening of plate hot rolling.

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