Run out table cooling equipment and coiling temperature control (CTC) system, especially mathematic models of a hot strip mill were introduced. Heat transfer models such as air convection model, heat radiation model and laminar cooling model, process control models such as segment tracking model, feedback control model, self-learning model and case-based reasoning model were detailed described. Since online application of the new CTC system, the laminar cooling control system has been running stably and reliably with a high precision of coiling temperature.
Coiling temperature of hot rolled strip is one of the important parameters which affect performances of hot rolled strip. The control of coiling temperature is highly nonlinear and time-varying. Based on the laminar cooling control system of a hot rolling plant, a coiling temperature prediction model based on BP neural network was established. Many factors which affect coiling temperature control were taken into account, and the BP neural network was trained by actual production data. The simulation was carried out, which indicates that coiling temperature can be predicted precisely, and the BP neural network model has the prospect of online application.
Recently degradable Mg matrix composites as a promising candidate for degradable downhole tools application have aroused extensive interest. In the present work, the effects of heat treatment (solution treatment and artificial aging) on the microstructure, mechanical properties and degradation behaviors of the newly developed hollow glass microsphere reinforced Mg-Al15-Zn6-Cu1.5 composites were investigated. The results show that the solution treatment causes the β-Mg17Al12 phase and Mg32(Al,Zn)49 phase to dissolve into the α-Mg matrix and the coarse eutectic τ-Al2CuMg phase to translate into blocky morphology. Aging treatment causes the β phase to precipitate at the grain boundaries or the edge of the residual second phases in lamellar and blocky morphology. After solution treatment, the ductility of the composites was significantly increased, while the following aging treatment could significantly increase the ultimate compressive strength (UCS), hardness and degradation rate. The composites solution treated at 420 °C for 20 h and aged at 200 °C for 24 h shows the higher degradation rate of 6.5 mg·cm-2·h-1 in 3 wt.% KCl at ambient temperature, with UCS of 471 MPa, Brinell hardness of 115 HB and fracture strain of 8.7 %, this outstanding comprehensive performance is more suitable for degradable downhole tools application.
Currently, Al-Si alloy is one of the most widely studied aluminum alloy for the phase change thermal storage materials which can be used in solar thermal power generation. However, there still exist some problems to be solved on Al-Si alloy in the present researches. For instance, the latent heat of Al-20%Si alloy is lower than that of Al-12%Si alloy in some papers while the an opposite conclusion was draw in other papers. To solve this problem, five kinds of Al-Si alloy were designed in this investigation, and the mass fraction of silicon was 4%, 8%, 12%, 16% and 20% respectively. The latent heat value of these alloys was determined using an SII TG/DTA 6300 differential thermal analyzer. According to the phase diagram and photomicrographs as well as the measured values, the quantitative expression of the relationship between alloy composition and the latent heat of Al-Si alloy were obtained. And the two quantitative relational expressions (Y1=13.14x+372.05 for the hypoeutectic alloy and Y2=-4.72x+599.01 for the hypereutectic alloy) were validated through the determination of latent heat of Al-6%Si alloy and Al-14%Si alloy.
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