Papers by Author: Yan Xia Chen

Abstract: The grain size evolvement of AZ31 magnesium alloy during high ratio extrusion (HRE) was investigated by experiment and numerical simulation. A Yada model was established according to the results of experimental study and trial calculation. Effects of the deformation temperature, extrusion ratio and extrusion velocity on the grain size were analyzed. The results showed that the microstructure of the AZ31 alloy was dramatically refined by high ratio extrusion. The deformation conditions exhibited obvious effects on the grain size, and the deformation conditions were interplaying and interacting with each other during the HRE process. Compared to the deformation temperature and extrusion velocity, the severe plastic deformation induced by the high ratio extrusion is a major cause of grain refinement. With the increasing of the extrusion velocity, the grains could be refined due to a shorter recrystallized grain growth time. At the same time, the deformation temperature increased with the increasing of the plastic strain rate, which results in faster recrystallized grain growth. Finally, recommended method is advised to further refine the grain size.

Abstract: In the paper, flow status and solidification status of molten steel in inner-outer couple cooling mold in the filling process are simulated by using fluid dynamics software Flow-3d, and obtain distributing diagrams of flow field and temperature field and free-surface shape diagrams in the filling process. Influences of flow field and temperature field of filling process on solidification are analyzed in the slab continuous casting. It is indicated that inner cooler can improve molten steel flow status, which is favorable to inclusion in molten steel floating up, quicken the solidification rate of molten steel in the mold.

Abstract: A new technology of high efficiency concasting based on inner-outer couple cooling of molten steel in a mould has been advanced, that is to set an inner cooling apparatus, U shape pipes, in a mould. The flow status of molten steel in mould with inner cooling apparatus is analyzed by using fluid dynamics analysis software FLUENT, and compared with that without inner cooling apparatus. It is found that the inner U-shape cooling apparatus can make molten steel flow with a lower impact depth which is favourable to inclusion in steel floating up.

Abstract: The numeric simulation of effect of X-shape submerged nozzle on flow of molten steel in a mold for 160mm×160mm concasting billet has been carried out by viscous fluid mechanics theory and CFD software Fluent. It was verified that during pouring with X-shape submerged nozzle, the vortex molten steel entering into mold by guide of vortex guidance channel which was formed with top and bottom surface of two semioval flow guidance plate and invert taper pipe to availably reduce impact depth, promote inclusion and gas bubble aggregating and floating off, and improve concasting efficiency.