| China has the largest number of endless rolling production lines and the largest production capacity in the world.With the rapid development of China’s endless rolling technology.ESP’s advanced short-process endless rolling technology pursues high shortprocess.Due to the obvious inflexible connection,the production equipment process frequently restricts its technical performance,resulting in frequent stopping and changing of finishing mill work rolls due to roll wear.In this paper,inline roll change for the endless rolling process is proposed to achieve inline work roll changing without stopping the finishing mill.The Equivalent substitution method has been used on ASTM-316 L as the experimental material to conduct basic research and simulation of theoretical control of the flexible rolling process and hot deformation parameters coupled with deformation,recrystallization,and microstructure characterization.Based on the single-pass hot compression experiment.The coupling behavior of dynamic softening and hot deformation parameters is investigated.The flow stress curves and the correspondence value between work hardening and dynamic softening are analyzed to determine the critical conditions for DRX of the experimental steel.The relationship between DRX critical conditions and peak conditions are revealed.The Zener-Hollomon equation is established in coupled with the high-temperature plastic deformation stress,strain rate,and temperature.Based on the fusion of current DRX theoretical models with quantitative DRV theory,a new DRX model algorithm is developed.The results show that the experimental and predicted values are in good agreement.Based on the dynamic material model,the 3D hot processing map of the experimental steel was established,and the hot processing stability region was determined.The microstructure and morphology of the DRX characteristic were characterized using OM and EBSD during the steady and transient mutant states.The results show that the DRX mechanism varies with deformation interval at constant deformation temperature and strain rate.At high deformation temperature and low strain rate,the DRX mechanism is primarily DDRX,and vice versa,the DRX mechanism is primarily CDRX.There are various DRX mechanisms in the strain rate transient mutation high-temperature plastic deformation state to coordinate the role of the constant deformation temperature.When the strain rate changes from low to high rate process,the DRX mechanism will shift from DDRX to CDRX.Based on the double-pass hot compression experiment.The static softening of the interpass interval,as well as its coupling behavior of hot deformation parameters,were studied.The variation regulations of SRX and MDRX with hot deformation parameters are revealed by evaluating the flow stress curves of the experimental steel during double-pass high-temperature plastic deformation.The results indicated that the second pass flow stress of SRX is greatly affected by interpass time,deformation temperature,and strain.In comparison to MDRX,SRX requires more time to inoculate and nucleate and is highly influenced by the initial strain.The kinetic models of SRX and MDRX were established,and the results showed that the experimental and predicted values are in good agreement.The EBSD was used to characterize the microstructure and morphology of SRX and MDRX during the interpass interval.The effects of hot deformation process parameters on the static softening microstructure,morphology and grain size of the experimental steel were investigated.The results showed that the increase of deformation temperature and strain rate could promote the process of SRX and MDRX,improve the static softening effect.Under the condition of constant deformation temperature and strain rate,Increasing the initial strain can increase the volume fraction of SRX.Increasing the deformation temperature or decreasing the strain rate can increase the grain size of MDRX.Compared with the initial strain,the static softening effect of deformation temperature and strain rate during interpass time is more obvious.Based on the finite element simulation technology,the numerical simulation and process optimization research during the transient mutation of inline roll change for the endless rolling process was carried out.Integrated the experimental steel’s high-temperature plastic flow behavior,stress-strain relationship,recrystallization kinetic model,and embedded Deform-3D finite element simulation software.The simulation platform of transient mutation of inline roll change for the endless rolling process was established to simulate the transient mutation of flexible rolling with variable parameters on the DRX behavior of the strip.The results show that the reduction rate,work roll withdraw speed,work roll input speed,deformation temperature and roll diameter have important effects on the microstructure uniformity of the strip along the thickness direction.Smaller reduction,higher roll withdraw speed and input speed,lower deformation temperature are conducive to reducing the DRX volume fraction gradient,to avoid causing stress concentration and instability phenomena.The roll diameter has less effect on the DRX volume fraction gradient of the core and surface of the strip.Therefore,it is necessary to consider the mill load and roll quality for a inline roll change for the endless rolling process according to the actual rolling process.This research develops a theoretical framework for the synergistic regulation of rolling strip microstructure characterization and mechanical properties during the inline roll change for the endless rolling process.Develops multiple theories and methods for the forming process,microstructure characterization,and mechanical property prediction during the inline roll change for the endless rolling process.These findings will enhance the ability of endless rolling equipment-process-product adaptation and control in the presence of inline roll change state.Promote industry to achieve more efficient,green and intelligent production. |
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