Intelligent Recognition Model of Hot Rolling Strip Edge Defects Based on Deep Learning

The edge of a hot rolling strip corresponds to the area where surface defects often occur. The morphologies of several common edge defects are similar to one another, thereby leading to easy error detection. To improve the detection accuracy of edge defects, the authors of this paper first classified the common edge defects and then made a dataset of edge defect images on this basis. Subsequently, edge defect recognition models were established on the basis of LeNet-5, AlexNet, and VggNet-16 by using a convolutional neural network as the core. Through multiple groups of training and recognition experiments, the model’s accuracy and recognition time of a single defect image were analyzed and compared with recognition models with different learning rates and sample batches. The experimental results showed that the recognition model based on the AlexNet had a maximum accuracy of 93.5%, and the average recognition time of a single defect image was 0.0035 s, which could meet the industry requirement. The research results in this paper provide a new method and thought for the fine detection of edge defects in hot rolling strips and have practical significance for improving the surface quality of hot rolling strips.

Improving the stability of high embankment slopes on weak foundations

The article considers the issues of assessing the stability of non-standard soil-geological systems in difficult conditions. An analytical review of modern methods and tools for assessing the stability of embankment slopes is carried out. The features of the work of the embankment in the areas of the spread of permafrost are considered. The features of the design of embankments on permafrost soils with the preservation or partial thawing of frozen soils have been studied. Two versions of the calculated static schemes of sliding surfaces are presented: base - subgrade and base - subgrade - pavement. Based on the results of field studies, the physical and mechanical characteristics of the soils of the embankment and the base of the subgrade were determined, which became the basis for mathematical modeling and assessment of the stability of the embankment slopes. In software packages GeoStab and Geo5, based on the finite element method and the results of field studies, digital models of embankments were built on a weak foundation. The calculation of the stability of the system “base - subgrade” under the action of a standard uniformly distributed load has been performed. Two models of the system and the base - subgrade - road surface are considered: without cracks on the rolling strip and with cracks. It was found that coating defects affect the stability of the system only in the presence of an earthquake of medium strength and more. Recommendations for strengthening the slopes of embankments operating in difficult soil-geological conditions are given.

Effects of Ultrasonic Bending Vibration Introduced by an L-Shaped Ultrasonic Rod on the Microstructure and Properties of a 1060 Aluminum Alloy Strip Formed by Twin-Roll Casting

In order to achieve the industrial application of ultrasonic energy in the continuous casting and rolling production of aluminum alloy, a new type of L-shaped ultrasonic rod was used to introduce an ultrasonic bending vibration into the aluminum melt in the launder during the horizontal twin-roll continuous casting and rolling process of a 1060 aluminum alloy. The effects of the ultrasonic bending vibration on the microstructure and properties of the 1060 aluminum alloy cast rolling strip and its subsequent cold rolling strip were studied experimentally, and the effect of the ultrasonic-assisted refining with different amounts of Al-Ti-B refiner was explored. The results show that under the same addition amount of Al-Ti-B refiner, the ultrasonic bending vibration can refine the grains of the cast rolling strip, make the distribution of precipitates more uniform, reduce the slag inclusion defects, and improve the mechanical properties to a certain extent. The microstructure and properties of the ultrasonic cast rolling strip with 0.18 wt% Al-Ti-B refiner or 0.12 wt% Al-Ti-B refiner are better than those of the conventional cast rolling strip, but the microstructure and properties of the ultrasonic cast rolling strip with 0.09 wt% Al-Ti-B refiner are slightly worse than those of the conventional cast rolling strip. Moreover, after cold rolling, the effect of the ultrasonic bending vibration on the improvement of the microstructure and properties of the aluminum alloy strip is inherited. A comprehensive analysis shows that the use of ultrasonic energy in this paper cannot completely replace the effect of the Al-Ti-B refiner, but it can reduce the addition amount of the Al-Ti-B refiner by 1/3.

Automated control of rolling modes on plate mills

Indicators of rolling quality and rolling process are presented, which determine the efficiency of plate mill operation. The purposes of the automated control of rolling which consist in achievement of an optimum ratio of the mentioned indicators, and division of control channels (when it’s possible) achiev-ing the best values of each indicator named above. Control of rolling modes (compression on passes, speeds, cooling) provides the main effect in indicators quality formation of hire and rolling process. The statement of the problem of automated rolling control is given. The choice of the optimized indicator in the problem of automatic rolling control is determined by its economic significance, the nature of the interrelation with the technological parameters and controls. One of the most economically significant for plate mills is the coefficient of metal consumption of the workpiece per ton of rolled product, or the yield, which depends on the accuracy of the implementation of the specified geometric dimensions of the rolling strip. The formulation of the problem of ensuring the minimum value of deviations in the thickness (width) of the strip from the specified value is given. The problem of optimization on one of three indicators of the rolling process is also formulated: the equivalent torque of the main drive, the electricity consumption for rolling and the time consumption of the rolling cycle, which are determined by the entire course of the rolling cycle, i.e. applied management strategy. The principles of solving the problem of automatic control of rolling modes are described. The rolling control strategies used in the ACS TP of plate mills are considered. Methods of constructing mathematical models for ACS TP of plate mills, as well as their adaptation, are described.

Study on Amplitude and Flatness Characteristics of Elastic Thin Strip under Fluid–Structure Interaction Vibration Excited by Unsteady Airflow

Based on unsteady airflow excitation and elastic thin strip vibration theory, a SI-FLAT flatness meter was taken as the research object, and an amplitude–residual stress simulation analysis model of the cold rolling strip under aerodynamic loads was established by using ANSYS Workbench. First, the influences of fluid–structure interaction on the strip amplitude distribution and the flatness calculation deviation were analyzed. It was found that the analysis with fluid–structure interaction matched the actual measurement of the flatness meter better. Then, the influences of different aerodynamic loads and tensions on the strip midpoint amplitude and the flatness calculation deviation were analyzed. It was found that when alternating aerodynamic loads increased, the strip amplitude increased in the form of a quadratic polynomial. However, when the tensions decreased, the strip amplitude decreased exponentially. The strip dimensions also influenced the amplitude of vibration: The wider and thinner the strip, the larger the amplitude. Finally, the influences of different flatness defects on the strip amplitude distribution and the flatness calculation deviation were analyzed. The deviation was serious on the strip edge, and the fluctuation characteristics of the deviation were opposite to those of the initial flatness defects.

Microstructure Evolution during the Production of Dual Phase and Transformation Induced Plasticity Steels Using Modified Strip Casting Simulated in The Laboratory

Instead of conventional steel making and continuous casting followed by hot and cold rolling, strip casting technology modified with the addition of a continuous annealing stage (namely, modified strip casting) is a promising short-route for producing ferrite-martensite dual-phase (DP) and multi-phase transformation-induced plasticity (TRIP) steels. However, at present, the multi-phase steels are not manufactured by the modified strip casting, due to insufficient knowledge about phase transformations occurring during in-line heat treatment. This study analysed the phase transformations, particularly the formation of ferrite, bainite and martensite and the retention of austenite, in one 0.17C-1.52Si-1.61Mn-0.195Cr (wt. %) steel subjected to the modified strip casting simulated in the laboratory. Through the adjustment of temperature and holding time, the characteristic microstructures for DP and TRIP steels have been obtained. The DP steel showed comparable tensile properties with industrial DP 590 and the TRIP steel had a lower strength but a higher ductility than those industrially produced TRIP steels. The strength could be further enhanced by the application of deformation and/or the addition of alloying elements. This study indicates that the modified strip casting technology is a promising new route to produce steels with multi-phase microstructures in the future.