The Inverse Analysis Of Interface Heat Transfer Coefficient At The Metal/Mold In Water-cooled Mould Casting

Water cooling mold casting is a new kind of technology to make steel ingots rapidly solidified. However, the phenomena of the central shrinkage and segregation of the water-cooled ingot is serious. As the high cost of the experiment, numerical simulation has become an important way to improve ingot internal defects and optimize ingot design. Boundary condition is not only the control condition of the solidification process, but also the necessary conditions for the numerical simulation technology. Because of the complicated boundary condition of ingot mold and few studies on it, the central shrinkage of the large steel ingot has not been improved. Therefore, the influence on the boundary conditions of interface heat transfer coefficient in the casting solidification process is studied in this paper.The cooling curve is gotten from different sites(four points in the casting, one point in the mold) in metal/mold experiment devices, water-cooled experimental device and air gap width experimental device. In the casting solidification process, the metal/mold interface heat transfer coefficient is reversely solved by the non-linear estimate calculation method and the simulation software of PROCAST.Results showed that the metal/mold interface heat transfer coefficient is ranged from 145W/m2·K to 524W/m2·K. Put the value into the simulation software and compare the measured curve with simulated curve to verify the validity of the non-linear estimate calculation method.The interface heat transfer coefficient under different cooling speeds are:When the cooling speed is from 0.5m/s to 1.7m/s and time is 0~150s, the interfacial temperature difference and temperature gradient increased gradually, but the increase degree of the temperature gradient is higher than that under interfacial temperature difference, and the interface heat transfer coefficient is from 1650W/m2·K up to 2200W/m2·K.Under the same flow rates and in difference temperature period, the interface temperature difference increased and the temperature gradient decreased with time increase, the interface heat transfer coefficient is decreased.The interface heat transfer coefficient in different gap width are:air gap is built as the thickness reached to 35mm; when the period is 150 s ~ 300 s, the width of air gap increases from 5 mm to 30 mm, with the decrease of the interfacial temperature difference and the increase of the temperature gradient, the interface heat transfer coefficient is from 270W/m2·K down to 50W/m2·K. Under the same width of the air gap and in different temperature ranges, the interface temperature difference increased and temperature gradients decreased with time increased, the interface heat transfer coefficient is decreased.