In this paper, the wear of work ROLL in HOT plate ROLLing is introduced and the parameters affecting wear mechanisms in HOT strip mill are investigated. In addition, different wear mechanisms in HOT ROLLing and the differences between these mechanisms in different stands are explained. Using the finite element method and the ROLLing equations, a work ROLL wear model is proposed. Wear is modeled using the resultant pressure distribution along the ROLL barrel. To obtain the tentative coefficient, summation of wear in each pass schedule is obtained and calibrated via actual wear of samples tested in the Mobarakeh Steel Company. Finally, the theoretical wear values are compared with those of the experiment. The predicted wear profiles are found to be in good agreement with those of the experimental measured values.

Work ROLLs in the HOT ring ROLLing process are susceptible to various damages due to the contact with HOT metal. Thermo-mechanical fatigue is one of these damages. In order to predict failure resulting from the thermo-mechanical stress in the work ROLLs, the developed code in ABAQUS was used. A comparison between three-and two-dimensional models was made and also, thermal and thermo-mechanical responses of work ROLLs with variable boundary conditions were investigated. The results demonstrated that by applying mechanical and thermal loads separately or simultaneously, the response of work ROLLs is completely different. In the mandrel, the location of the maximum equivalent stress is on the surface, while the location of equivalent maximum stress is on the subsurface of the main ROLL. Upon utilizing cumulative damage rules and the stress-life method, the thermo-mechanical fatigue life was estimated. The cumulated damage to the surface of the mandrel was higher than that to subsurface regions. In contrast to the mandrel, the cumulated damage to the subsurface of the main ROLL was higher than that to the surface regions. In HOT ring ROLLing machines, these locations are prone to crack initiation as a result of the thermo-mechanical fatigue of the work ROLLs.

This paper introduces an artificial neural network (ANN) application to a HOT strip mill to improve the model’s prediction ability for ROLLing force and ROLLing torque, as a function of various process parameters. To obtain a data basis for training and validation of the neural network, numerous three dimensional finite element simulations were carried out for different sets of process variables. Experimental data were compared with the finite element predictions to verify the model accuracy. Thus the ABAQUS and MATLAB soft wares are used to simulate the finite element method and an artificial neural network, respectively. The back-propagation algorithm and Levenberg-Marquardt Training function were used in the artificial neural network. The input variables are selected to be, initial temperature of the strip, interface heat-transfer coefficient between strip and work ROLL, percentage of thickness reduction, initial thickness and ROLLing speed. The resulted ANN model is feasible for on-line control and ROLLing schedule optimization and can be easily and rapidly predicted the ROLL force and ROLL torque.

The final HOT strip profile is a superposition of the ROLL initial crown, the ROLL bending and flattening crown, the ROLL wearing crown and the ROLL thermal crown. In this research, linear regression models are proposed to predict the ROLL force, the ROLL wearing crown and the ROLL thermal crown using experimental data provided by Mobarake Steel Complex (MSC). The Euler-Bernoulli beam theory based on elasticity approach is also used to predict the ROLL bending and flattening crown. Finally, the work ROLL initial crown in order to obtain desired strip profile in HOT ROLLing is predicted utilizing a computer programming. The obtained initial crowns are then used for seven stands of an actual ROLL schedule for HOT strip mill of MSC. The measured strip profile shows a good agreement with the desired one for the mentioned mill.

In this study optimal thickness of WC-Co spray coating by HVOF (High Velocity Oxy Fuel) method on the surface of HOT ROLLing pinch-ROLL ROLLer by utilizing finite element method were investigated. The task of pinch-ROLL was to get and guide sheets toward the coilers. The working environment of these components was acidic and they worked in temperature and humid ambient. The surface of these ROLLers was worn due to impact and movement of sheet on it. At first, the critical condition of pinch-ROLL was determined. Results showed that working condition of the pinch-ROLL at the initial impact was worse than other working times. Also hard and thin sheets made the more critical condition. After the surface of pinch-ROLL was coated analysis showed that deformation and failure were created in coating. In this condition the best thickness of coating was about 600 microns that caused minimum shear stress distribution both in the surface coating and in the interface of coating/substrate.

TWinning Induced Plasticity (TWIP) steels, with high manganese percent (17-35%), are used in automotive bodies. Their microstructure at room temperature is austenitic and due to low stacking fault energy, major deformation mechanism in them is twinning inside austenite grains which, on the other hand, leads to enhance mechanical strength in steel. In order to improve the mechanical properties, by adding carbide forming elements to steel, their strength has been increased. To this end, the castings of steel, microstructure analysis by optical and scanning electron microscopy (SEM) were studied. The results showed that the cold-ROLLing this steel, will increase the strength and ductility to great exgant.

Purpose: Novice runners are at high risk of running-related injuries. However, their injury mechanisms are less well understood. The purpose of this study was to evaluate the effect of running-induced fatigue on foot ROLL-over pattern in novice runners.Methods: Eighteen (12 male and 6 female) novice runners participated in this study. Before and after the fatigue, plantar load distribution was recorded by Footscan system. Peak plantar pressure, peak force underneath of each zone and Medio-lateral force distribution ratio were calculated during forefoot push-off phase. Furthermore, temporal data such as time to peak force for each region and duration percent for each phase were calculated.Results: After the fatigue, an increase in forefoot and midfoot loading was observed. Results showed statistically significant reduction in the Medio-lateral force distribution ratio in forefoot push off (p=0.029). Moreover, timing percent of initial contact phase and forefoot contact phase were decreased (p=0.001 and p=0.009 respectively) and percent of forefoot push off phase duration was increased significantly (p=0.036). Time to peak force in the 4th metatarsal reduced.Conclusion: The findings of the present study demonstrated that running-induced fatigue caused load and plantar pressure distribution consequently, ROLL-over deviations in novice runners. These results may provide useful information related to several running related injuries.

In this paper, a semi-analytical model was proposed to superimpose the initial residual stress components on the work ROLL surface and subsurface to minimize the maximum value of Von-Mises Stresses (MVMS) during the HOT ROLLing process to reduce the possibility of ROLL wear and increase the fatigue life. A Finite Element Model (FEM) was proposed to assess the temperature and thermomechanical stress in work ROLL during HOT ROLLing. An analytical method was developed to implement the three initial residual stress components designed by the full factorial analysis of variance (ANOVA) method in the obtained FEM thermomechanical stress results. An Artificial Neural Network (ANN) was used to establish an objective function to relate the initial residual stress components to the MVMS. Subsequently, the single and multi-objective Genetic Algorithm (GA) optimization were used to find the optimal value of initial residual stress components to minimize the MVMS on the surface and subsurface of the work ROLL. The results showed a significant reduction of boththe value and amplitude of the MVMS on surface and subsurface of a work ROLL during the HOT ROLLing process.