| 摘要 |
PURPOSE: A batch annealing method of ferrite stainless hot coils using heat treatment model is provided to prevent excessive annealing of an outer coiling part of the ferrite stainless hot coil and greatly improve material deviation between inner and outer coiling parts of the hot coil through development of heat treatment model. CONSTITUTION: The batch annealing method of ferrite stainless hot coil using heat treatment model comprises the steps of obtaining information on thickness, width and unit weight of an arbitrary ferrite stainless hot coil; element dividing a surface consisting of radius and width directions of the hot coil into a plurality of surfaces based on the information on width and unit weight of the hot coil; obtaining thermal conductivity, density and specific heat of the hot coil, determining a convention coefficient at each divided surface of the hot coil by obtaining a convection coefficient at outer and inner coiling parts of the coil and obtaining convection coefficient at upper and lower parts of the hot coil; determining a thermal conductivity coefficient according to thickness of the hot coil by obtaining a radius directional thermal conductivity coefficient of the coil and considering a correction value according to expansion between a gap between coils along with the radius directional thermal conductivity coefficient; determining radiation coefficient at the outer coiling part of the hot coil; predicting temperature distribution inside the hot coil by modelling a prediction model considering the obtained convection coefficient, thermal conductivity coefficient and radiation coefficient and each boundary condition by two dimensional finite element method; graphing the coolest point of the hot coil and change of temperature curve line according to temperature and time from the predicted temperature distribution; predicting the coolest point of the hot coil and temperature distribution of the outer coiling part; and obtaining the temperature change of a curved line according to temperature and time, and determining temperature and time in which deviation between the coolest point and the outer coiling part of the hot coil is minimized as the optimum annealing conditions of the hot coil.
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